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Jinks-Robertson, Sue

Positions:

Professor of Molecular Genetics and Microbiology

Molecular Genetics and Microbiology
School of Medicine

Member of the Duke Cancer Institute

Duke Cancer Institute
School of Medicine

Education:

Ph.D. 1983

Ph.D. — University of Wisconsin at Madison

News:

Grants:

Regulation of mitotic genome stability in yeast.

Administered By
Molecular Genetics and Microbiology
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
May 01, 2016
End Date
April 30, 2021

Molecular Mycology and Pathogenesis Training Program

Administered By
Molecular Genetics and Microbiology
AwardedBy
National Institutes of Health
Role
Mentor
Start Date
August 08, 2014
End Date
July 31, 2019

Non-Canonical Responses to DNA damage in Drosophila Polyploid Cells

Administered By
Pharmacology & Cancer Biology
AwardedBy
National Institutes of Health
Role
Collaborator
Start Date
March 01, 2015
End Date
February 28, 2018

Investigating the origin of spontaneous mitotic homologous recombination in Saccharomyces cerevisiae

Administered By
Molecular Genetics and Microbiology
AwardedBy
American Heart Association
Role
Principal Investigator
Start Date
July 01, 2015
End Date
June 30, 2017

Regulation of mitotic genome stability in yeast

Administered By
Molecular Genetics and Microbiology
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
August 01, 2006
End Date
June 30, 2016

Topoisomerase 1 and mutagenesis in yeast

Administered By
Molecular Genetics and Microbiology
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
May 01, 2012
End Date
April 30, 2016

Transcription-associated mutagenesis in yeast

Administered By
Molecular Genetics and Microbiology
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
August 01, 2010
End Date
July 31, 2015

Tolerance of spontaneous and induced DNA in yeast

Administered By
Molecular Genetics and Microbiology
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
January 01, 2002
End Date
February 28, 2011

Role of cross-link formation in Pol Zeta-dependent mutagenesis in S. cerevisiae

Administered By
Molecular Genetics and Microbiology
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
August 07, 2009
End Date
August 06, 2010
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Awards:

AAAS Fellows. American Association for the Advancement of Science, The.

Type
National
Awarded By
American Association for the Advancement of Science, The
Date
January 01, 2011

Publications:

Parallel analysis of ribonucleotide-dependent deletions produced by yeast Top1 in vitro and in vivo

Authors
Cho, J-E; Huang, S-YN; Burgers, PM; Shuman, S; Pommier, Y; Jinks-Robertson, S
MLA Citation
Cho, J-E, Huang, S-YN, Burgers, PM, Shuman, S, Pommier, Y, and Jinks-Robertson, S. "Parallel analysis of ribonucleotide-dependent deletions produced by yeast Top1 in vitro and in vivo." Nucleic Acids Research 44.16 (September 19, 2016): 7714-7721.
Source
crossref
Published In
Nucleic Acids Research
Volume
44
Issue
16
Publish Date
2016
Start Page
7714
End Page
7721
DOI
10.1093/nar/gkw495

Ribonucleotides and Transcription-Associated Mutagenesis in Yeast

Authors
Cho, J-E; Jinks-Robertson, S
MLA Citation
Cho, J-E, and Jinks-Robertson, S. "Ribonucleotides and Transcription-Associated Mutagenesis in Yeast." Journal of Molecular Biology (August 2016).
Source
crossref
Published In
Journal of Molecular Biology
Publish Date
2016
DOI
10.1016/j.jmb.2016.08.005

Elevated Genome-Wide Instability in Yeast Mutants Lacking RNase H Activity.

Two types of RNA:DNA associations can lead to genome instability: the formation of R-loops during transcription and the incorporation of ribonucleotide monophosphates (rNMPs) into DNA during replication. Both ribonuclease (RNase) H1 and RNase H2 degrade the RNA component of R-loops, whereas only RNase H2 can remove one or a few rNMPs from DNA. We performed high-resolution mapping of mitotic recombination events throughout the yeast genome in diploid strains of Saccharomyces cerevisiae lacking RNase H1 (rnh1Δ), RNase H2 (rnh201Δ), or both RNase H1 and RNase H2 (rnh1Δ rnh201Δ). We found little effect on recombination in the rnh1Δ strain, but elevated recombination in both the rnh201Δ and the double-mutant strains; levels of recombination in the double mutant were ∼50% higher than in the rnh201 single-mutant strain. An rnh201Δ mutant that additionally contained a mutation that reduces rNMP incorporation by DNA polymerase ε (pol2-M644L) had a level of instability similar to that observed in the presence of wild-type Pol ε. This result suggests that the elevated recombination observed in the absence of only RNase H2 is primarily a consequence of R-loops rather than misincorporated rNMPs.

Authors
O'Connell, K; Jinks-Robertson, S; Petes, TD
MLA Citation
O'Connell, K, Jinks-Robertson, S, and Petes, TD. "Elevated Genome-Wide Instability in Yeast Mutants Lacking RNase H Activity." Genetics 201.3 (November 2015): 963-975.
PMID
26400613
Source
epmc
Published In
Genetics
Volume
201
Issue
3
Publish Date
2015
Start Page
963
End Page
975
DOI
10.1534/genetics.115.182725

SMRT Sequencing for Parallel Analysis of Multiple Targets and Accurate SNP Phasing.

Single-molecule real-time (SMRT) sequencing generates much longer reads than other widely used next-generation (next-gen) sequencing methods, but its application to whole genome/exome analysis has been limited. Here, we describe the use of SMRT sequencing coupled with barcoding to simultaneously analyze one or a small number of genomic targets derived from multiple sources. In the budding yeast system, SMRT sequencing was used to analyze strand-exchange intermediates generated during mitotic recombination and to analyze genetic changes in a forward mutation assay. The general barcoding-SMRT approach was then extended to diffuse large B-cell lymphoma primary tumors and cell lines, where detected changes agreed with prior Illumina exome sequencing. A distinct advantage afforded by SMRT sequencing over other next-gen methods is that it immediately provides the linkage relationships between SNPs in the target segment sequenced. The strength of our approach for mutation/recombination studies (as well as linkage identification) derives from its inherent computational simplicity coupled with a lack of reliance on sophisticated statistical analyses.

Authors
Guo, X; Lehner, K; O'Connell, K; Zhang, J; Dave, SS; Jinks-Robertson, S
MLA Citation
Guo, X, Lehner, K, O'Connell, K, Zhang, J, Dave, SS, and Jinks-Robertson, S. "SMRT Sequencing for Parallel Analysis of Multiple Targets and Accurate SNP Phasing." G3 (Bethesda, Md.) 5.12 (October 23, 2015): 2801-2808.
PMID
26497143
Source
epmc
Published In
G3 (Bethesda, Md.)
Volume
5
Issue
12
Publish Date
2015
Start Page
2801
End Page
2808
DOI
10.1534/g3.115.023317

Topoisomerase 1-dependent deletions initiated by incision at ribonucleotides are biased to the non-transcribed strand of a highly activated reporter.

DNA polymerases incorporate ribonucleoside monophosphates (rNMPs) into genomic DNA at a low level and such rNMPs are efficiently removed in an error-free manner by ribonuclease (RNase) H2. In the absence of RNase H2 in budding yeast, persistent rNMPs give rise to short deletions via a mutagenic process initiated by Topoisomerase 1 (Top1). We examined the activity of a 2-bp, rNMP-dependent deletion hotspot [the (TG)2 hotspot] when on the transcribed or non-transcribed strand (TS or NTS, respectively) of a reporter placed in both orientations near a strong origin of replication. Under low-transcription conditions, hotspot activity depended on whether the (TG)2 sequence was part of the newly synthesized leading or lagging strand of replication. In agreement with an earlier study, deletions occurred at a much higher rate when (TG)2 was on the nascent leading strand. Under high-transcription conditions, however, hotspot activity was not dependent on replication direction, but rather on whether the (TG)2 sequence was on the TS or NTS of the reporter. Deletion rates were several orders of magnitude higher when (TG)2 was on the NTS. These results highlight the complex interplay between replication and transcription in regulating Top1-dependent genetic instability.

Authors
Cho, J-E; Kim, N; Jinks-Robertson, S
MLA Citation
Cho, J-E, Kim, N, and Jinks-Robertson, S. "Topoisomerase 1-dependent deletions initiated by incision at ribonucleotides are biased to the non-transcribed strand of a highly activated reporter." Nucleic acids research 43.19 (October 2015): 9306-9313.
PMID
26271994
Source
epmc
Published In
Nucleic Acids Research
Volume
43
Issue
19
Publish Date
2015
Start Page
9306
End Page
9313
DOI
10.1093/nar/gkv824

Genome-destabilizing effects associated with top1 loss or accumulation of top1 cleavage complexes in yeast.

Topoisomerase 1 (Top1), a Type IB topoisomerase, functions to relieve transcription- and replication-associated torsional stress in DNA. We investigated the effects of Top1 on genome stability in Saccharomyces cerevisiae using two different assays. First, a sectoring assay that detects loss of heterozygosity (LOH) on a specific chromosome was used to measure reciprocal crossover (RCO) rates. Features of individual RCO events were then molecularly characterized using chromosome-specific microarrays. In the second assay, cells were sub-cultured for 250 generations and LOH was examined genome-wide using microarrays. Though loss of Top1 did not destabilize single-copy genomic regions, RCO events were more complex than in a wild-type strain. In contrast to the stability of single-copy regions, sub-culturing experiments revealed that top1 mutants had greatly elevated levels of instability within the tandemly-repeated ribosomal RNA genes (in agreement with previous results). An intermediate in the enzymatic reaction catalyzed by Top1 is the covalent attachment of Top1 to the cleaved DNA. The resulting Top1 cleavage complex (Top1cc) is usually transient but can be stabilized by the drug camptothecin (CPT) or by the top1-T722A allele. We found that increased levels of the Top1cc resulted in a five- to ten-fold increase in RCOs and greatly increased instability within the rDNA and CUP1 tandem arrays. A detailed analysis of the events in strains with elevated levels of Top1cc suggests that recombinogenic DNA lesions are introduced during or after DNA synthesis. These results have important implications for understanding the effects of CPT as a chemotherapeutic agent.

Authors
Andersen, SL; Sloan, RS; Petes, TD; Jinks-Robertson, S
MLA Citation
Andersen, SL, Sloan, RS, Petes, TD, and Jinks-Robertson, S. "Genome-destabilizing effects associated with top1 loss or accumulation of top1 cleavage complexes in yeast." PLoS genetics 11.4 (April 2015): e1005098-.
PMID
25830313
Source
epmc
Published In
PLoS genetics
Volume
11
Issue
4
Publish Date
2015
Start Page
e1005098
DOI
10.1371/journal.pgen.1005098

Ribonucleotides in DNA: hidden in plain sight.

Authors
Jinks-Robertson, S; Klein, HL
MLA Citation
Jinks-Robertson, S, and Klein, HL. "Ribonucleotides in DNA: hidden in plain sight." Nature structural & molecular biology 22.3 (March 2015): 176-178.
PMID
25736085
Source
epmc
Published In
Nature Structural & Molecular Biology
Volume
22
Issue
3
Publish Date
2015
Start Page
176
End Page
178
DOI
10.1038/nsmb.2981

Topoisomerase I plays a critical role in suppressing genome instability at a highly transcribed G-quadruplex-forming sequence.

G-quadruplex or G4 DNA is a non-B secondary DNA structure that comprises a stacked array of guanine-quartets. Cellular processes such as transcription and replication can be hindered by unresolved DNA secondary structures potentially endangering genome maintenance. As G4-forming sequences are highly frequent throughout eukaryotic genomes, it is important to define what factors contribute to a G4 motif becoming a hotspot of genome instability. Using a genetic assay in Saccharomyces cerevisiae, we previously demonstrated that a potential G4-forming sequence derived from a guanine-run containing immunoglobulin switch Mu (Sμ) region becomes highly unstable when actively transcribed. Here we describe assays designed to survey spontaneous genome rearrangements initiated at the Sμ sequence in the context of large genomic areas. We demonstrate that, in the absence of Top1, a G4 DNA-forming sequence becomes a strong hotspot of gross chromosomal rearrangements and loss of heterozygosity associated with mitotic recombination within the ∼ 20 kb or ∼ 100 kb regions of yeast chromosome V or III, respectively. Transcription confers a critical strand bias since genome rearrangements at the G4-forming Sμ are elevated only when the guanine-runs are located on the non-transcribed strand. The direction of replication and transcription, when in a head-on orientation, further contribute to the elevated genome instability at a potential G4 DNA-forming sequence. The implications of our identification of Top1 as a critical factor in suppression of instability associated with potential G4 DNA-forming sequences are discussed.

Authors
Yadav, P; Harcy, V; Argueso, JL; Dominska, M; Jinks-Robertson, S; Kim, N
MLA Citation
Yadav, P, Harcy, V, Argueso, JL, Dominska, M, Jinks-Robertson, S, and Kim, N. "Topoisomerase I plays a critical role in suppressing genome instability at a highly transcribed G-quadruplex-forming sequence." PLoS genetics 10.12 (December 4, 2014): e1004839-.
PMID
25473964
Source
epmc
Published In
PLoS genetics
Volume
10
Issue
12
Publish Date
2014
Start Page
e1004839
DOI
10.1371/journal.pgen.1004839

Shared genetic pathways contribute to the tolerance of endogenous and low-dose exogenous DNA damage in yeast.

DNA damage that escapes repair and blocks replicative DNA polymerases is tolerated by bypass mechanisms that fall into two general categories: error-free template switching and error-prone translesion synthesis. Prior studies of DNA damage responses in Saccharomyces cerevisiae have demonstrated that repair mechanisms are critical for survival when a single, high dose of DNA damage is delivered, while bypass/tolerance mechanisms are more important for survival when the damage level is low and continuous (acute and chronic damage, respectively). In the current study, epistatic interactions between DNA-damage tolerance genes were examined and compared when haploid yeast cells were exposed to either chronic ultraviolet light or chronic methyl methanesulfonate. Results demonstrate that genes assigned to error-free and error-prone bypass pathways similarly promote survival in the presence of each type of chronic damage. In addition to using defined sources of chronic damage, rates of spontaneous mutations generated by the Pol ζ translesion synthesis DNA polymerase (complex insertions in a frameshift-reversion assay) were used to infer epistatic interactions between the same genes. Similar epistatic interactions were observed in analyses of spontaneous mutation rates, suggesting that chronic DNA-damage responses accurately reflect those used to tolerate spontaneous lesions. These results have important implications when considering what constitutes a safe and acceptable level of exogenous DNA damage.

Authors
Lehner, K; Jinks-Robertson, S
MLA Citation
Lehner, K, and Jinks-Robertson, S. "Shared genetic pathways contribute to the tolerance of endogenous and low-dose exogenous DNA damage in yeast." Genetics 198.2 (October 2014): 519-530.
PMID
25060101
Source
epmc
Published In
Genetics
Volume
198
Issue
2
Publish Date
2014
Start Page
519
End Page
530
DOI
10.1534/genetics.114.168617

The role of Dbf4-dependent protein kinase in DNA polymerase ζ-dependent mutagenesis in Saccharomyces cerevisiae.

The yeast Dbf4-dependent kinase (DDK) (composed of Dbf4 and Cdc7 subunits) is an essential, conserved Ser/Thr protein kinase that regulates multiple processes in the cell, including DNA replication, recombination and induced mutagenesis. Only DDK substrates important for replication and recombination have been identified. Consequently, the mechanism by which DDK regulates mutagenesis is unknown. The yeast mcm5-bob1 mutation that bypasses DDK's essential role in DNA replication was used here to examine whether loss of DDK affects spontaneous as well as induced mutagenesis. Using the sensitive lys2ΔA746 frameshift reversion assay, we show DDK is required to generate "complex" spontaneous mutations, which are a hallmark of the Polζ translesion synthesis DNA polymerase. DDK co-immunoprecipitated with the Rev7 regulatory, but not with the Rev3 polymerase subunit of Polζ. Conversely, Rev7 bound mainly to the Cdc7 kinase subunit and not to Dbf4. The Rev7 subunit of Polζ may be regulated by DDK phosphorylation as immunoprecipitates of yeast Cdc7 and also recombinant Xenopus DDK phosphorylated GST-Rev7 in vitro. In addition to promoting Polζ-dependent mutagenesis, DDK was also important for generating Polζ-independent large deletions that revert the lys2ΔA746 allele. The decrease in large deletions observed in the absence of DDK likely results from an increase in the rate of replication fork restart after an encounter with spontaneous DNA damage. Finally, nonepistatic, additive/synergistic UV sensitivity was observed in cdc7Δ pol32Δ and cdc7Δ pol30-K127R,K164R double mutants, suggesting that DDK may regulate Rev7 protein during postreplication "gap filling" rather than during "polymerase switching" by ubiquitinated and sumoylated modified Pol30 (PCNA) and Pol32.

Authors
Brandão, LN; Ferguson, R; Santoro, I; Jinks-Robertson, S; Sclafani, RA
MLA Citation
Brandão, LN, Ferguson, R, Santoro, I, Jinks-Robertson, S, and Sclafani, RA. "The role of Dbf4-dependent protein kinase in DNA polymerase ζ-dependent mutagenesis in Saccharomyces cerevisiae." Genetics 197.4 (August 2014): 1111-1122.
PMID
24875188
Source
epmc
Published In
Genetics
Volume
197
Issue
4
Publish Date
2014
Start Page
1111
End Page
1122
DOI
10.1534/genetics.114.165308

Transcription-associated mutagenesis.

Transcription requires unwinding complementary DNA strands, generating torsional stress, and sensitizing the exposed single strands to chemical reactions and endogenous damaging agents. In addition, transcription can occur concomitantly with the other major DNA metabolic processes (replication, repair, and recombination), creating opportunities for either cooperation or conflict. Genetic modifications associated with transcription are a global issue in the small genomes of microorganisms in which noncoding sequences are rare. Transcription likewise becomes significant when one considers that most of the human genome is transcriptionally active. In this review, we focus specifically on the mutagenic consequences of transcription. Mechanisms of transcription-associated mutagenesis in microorganisms are discussed, as is the role of transcription in somatic instability of the vertebrate immune system.

Authors
Jinks-Robertson, S; Bhagwat, AS
MLA Citation
Jinks-Robertson, S, and Bhagwat, AS. "Transcription-associated mutagenesis." Annual review of genetics 48 (January 2014): 341-359. (Review)
PMID
25251854
Source
epmc
Published In
Annual Review of Genetics
Volume
48
Publish Date
2014
Start Page
341
End Page
359
DOI
10.1146/annurev-genet-120213-092015

Roles of exonucleases and translesion synthesis DNA polymerases during mitotic gap repair in yeast

Transformation-based gap-repair assays have long been used to model the repair of mitotic double-strand breaks (DSBs) by homologous recombination in yeast. In the current study, we examine genetic requirements of two key processes involved in DSB repair: (1) the processive 5'-end resection that is required to efficiently engage a repair template and (2) the filling of resected ends by DNA polymerases. The specific gap-repair assay used allows repair events resolved as crossover versus noncrossover products to be distinguished, as well as the extent of heteroduplex DNA formed during recombination to be measured. To examine end resection, the efficiency and outcome of gap repair were monitored in the absence of the Exo1 exonuclease and the Sgs1 helicase. We found that either Exo1 or Sgs1 presence is sufficient to inhibit gap-repair efficiency over 10-fold, consistent with resection-mediated destruction of the introduced plasmid. In terms of DNA polymerase requirements for gap repair, we focused specifically on potential roles of the Pol ζ and Pol η translesion synthesis DNA polymerases. We found that both Pol ζ and Pol η are necessary for efficient gap repair and that each functions independently of the other. These polymerases may be involved either in the initiation of DNA synthesis from the an invading end, or in a gap-filling process that is required to complete recombination. © 2013 Elsevier B.V.

Authors
Guo, X; Jinks-Robertson, S
MLA Citation
Guo, X, and Jinks-Robertson, S. "Roles of exonucleases and translesion synthesis DNA polymerases during mitotic gap repair in yeast." DNA Repair 12.12 (December 1, 2013): 1024-1030.
PMID
24210827
Source
scopus
Published In
DNA Repair
Volume
12
Issue
12
Publish Date
2013
Start Page
1024
End Page
1030
DOI
10.1016/j.dnarep.2013.10.001

Removal of N-6-methyladenine by the nucleotide excision repair pathway triggers the repair of mismatches in yeast gap-repair intermediates

Gap-repair assays have been an important tool for studying the genetic control of homologous recombination in yeast. Sequence analysis of recombination products derived when a gapped plasmid is diverged relative to the chromosomal repair template additionally has been used to infer structures of strand-exchange intermediates. In the absence of the canonical mismatch repair pathway, mismatches present in these intermediates are expected to persist and segregate at the next round of DNA replication. In a mismatch repair defective (mlh1δ) background, however, we have observed that recombination-generated mismatches are often corrected to generate gene conversion or restoration events. In the analyses reported here, the source of the aberrant mismatch removal during gap repair was examined. We find that most mismatch removal is linked to the methylation status of the plasmid used in the gap-repair assay. Whereas more than half of Dam-methylated plasmids had patches of gene conversion and/or restoration interspersed with unrepaired mismatches, mismatch removal was observed in less than 10% of products obtained when un-methylated plasmids were used in transformation experiments. The methylation-linked removal of mismatches in recombination intermediates was due specifically to the nucleotide excision repair pathway, with such mismatch removal being partially counteracted by glycosylases of the base excision repair pathway. These data demonstrate that nucleotide excision repair activity is not limited to bulky, helix-distorting DNA lesions, but also targets removal of very modest perturbations in DNA structure. In addition to its effects on mismatch removal, methylation reduced the overall gap-repair efficiency, but this reduction was not affected by the status of excision repair pathways. Finally, gel purification of DNA prior to transformation reduced gap-repair efficiency four-fold in a nucleotide excision repair-defective background, indicating that the collateral introduction of UV damage can potentially compromise genetic interpretations. © 2013 Elsevier B.V.

Authors
Guo, X; Jinks-Robertson, S
MLA Citation
Guo, X, and Jinks-Robertson, S. "Removal of N-6-methyladenine by the nucleotide excision repair pathway triggers the repair of mismatches in yeast gap-repair intermediates." DNA Repair 12.12 (December 1, 2013): 1053-1061.
PMID
24120148
Source
scopus
Published In
DNA Repair
Volume
12
Issue
12
Publish Date
2013
Start Page
1053
End Page
1061
DOI
10.1016/j.dnarep.2013.09.006

RNA:DNA Hybrids Initiate Quasi-Palindrome-Associated Mutations in Highly Transcribed Yeast DNA

RNase H enzymes promote genetic stability by degrading aberrant RNA:DNA hybrids and by removing ribonucleotide monophosphates (rNMPs) that are present in duplex DNA. Here, we report that loss of RNase H2 in yeast is associated with mutations that extend identity between the arms of imperfect inverted repeats (quasi-palindromes or QPs), a mutation type generally attributed to a template switch during DNA synthesis. QP events were detected using frameshift-reversion assays and were only observed under conditions of high transcription. In striking contrast to transcription-associated short deletions that also are detected by these assays, QP events do not require Top1 activity. QP mutation rates are strongly affected by the direction of DNA replication and, in contrast to their elevation in the absence of RNase H2, are reduced when RNase H1 is additionally eliminated. Finally, transcription-associated QP events are limited by components of the nucleotide excision repair pathway and are promoted by translesion synthesis DNA polymerases. We suggest that QP mutations reflect either a transcription-associated perturbation of Okazaki-fragment processing, or the use of a nascent transcript to resume replication following a transcription-replication conflict. © 2013 Kim et al.

Authors
Kim, N; Cho, JE; Li, YC; Jinks-Robertson, S
MLA Citation
Kim, N, Cho, JE, Li, YC, and Jinks-Robertson, S. "RNA:DNA Hybrids Initiate Quasi-Palindrome-Associated Mutations in Highly Transcribed Yeast DNA." PLoS Genetics 9.11 (November 1, 2013).
PMID
24244191
Source
scopus
Published In
PLoS genetics
Volume
9
Issue
11
Publish Date
2013
DOI
10.1371/journal.pgen.1003924

Two distinct mechanisms of Topoisomerase 1-dependent mutagenesis in yeast.

Topoisomerase 1 (Top1) resolves transcription-associated supercoils by generating transient single-strand breaks in DNA. Top1 activity in yeast is a major source of transcription-associated mutagenesis, generating a distinctive mutation signature characterized by deletions in short, tandem repeats. A similar signature is associated with the persistence of ribonucleoside monophosphates (rNMPs) in DNA, and it also depends on Top1 activity. There is only partial overlap, however, between Top1-dependent deletion hotspots identified in highly transcribed DNA and those associated with rNMPs, suggesting the existence of both rNMP-dependent and rNMP-independent events. Here, we present genetic studies confirming that there are two distinct types of hotspots. Data suggest a novel model in which rNMP-dependent hotspots are generated by sequential Top1 reactions and are consistent with rNMP-independent hotspots reflecting processing of a trapped Top1 cleavage complex.

Authors
Cho, J-E; Kim, N; Li, YC; Jinks-Robertson, S
MLA Citation
Cho, J-E, Kim, N, Li, YC, and Jinks-Robertson, S. "Two distinct mechanisms of Topoisomerase 1-dependent mutagenesis in yeast." DNA Repair (Amst) 12.3 (March 1, 2013): 205-211.
PMID
23305949
Source
pubmed
Published In
DNA Repair
Volume
12
Issue
3
Publish Date
2013
Start Page
205
End Page
211
DOI
10.1016/j.dnarep.2012.12.004

Roles of exonucleases and translesion synthesis DNA polymerases during mitotic gap repair in yeast

Transformation-based gap-repair assays have long been used to model the repair of mitotic double-strand breaks (DSBs) by homologous recombination in yeast. In the current study, we examine genetic requirements of two key processes involved in DSB repair: (1) the processive 5'-end resection that is required to efficiently engage a repair template and (2) the filling of resected ends by DNA polymerases. The specific gap-repair assay used allows repair events resolved as crossover versus noncrossover products to be distinguished, as well as the extent of heteroduplex DNA formed during recombination to be measured. To examine end resection, the efficiency and outcome of gap repair were monitored in the absence of the Exo1 exonuclease and the Sgs1 helicase. We found that either Exo1 or Sgs1 presence is sufficient to inhibit gap-repair efficiency over 10-fold, consistent with resection-mediated destruction of the introduced plasmid. In terms of DNA polymerase requirements for gap repair, we focused specifically on potential roles of the Pol ζ and Pol η translesion synthesis DNA polymerases. We found that both Pol ζ and Pol η are necessary for efficient gap repair and that each functions independently of the other. These polymerases may be involved either in the initiation of DNA synthesis from the an invading end, or in a gap-filling process that is required to complete recombination. © 2013 Elsevier B.V.

Authors
Guo, X; Jinks-Robertson, S
MLA Citation
Guo, X, and Jinks-Robertson, S. "Roles of exonucleases and translesion synthesis DNA polymerases during mitotic gap repair in yeast." DNA Repair 12.12 (2013): 1024-1030.
Source
scival
Published In
DNA Repair
Volume
12
Issue
12
Publish Date
2013
Start Page
1024
End Page
1030
DOI
10.1016/j.dnarep.2013.10.001

Heteroduplex DNA Position Defines the Roles of the Sgs1, Srs2, and Mph1 Helicases in Promoting Distinct Recombination Outcomes

The contributions of the Sgs1, Mph1, and Srs2 DNA helicases during mitotic double-strand break (DSB) repair in yeast were investigated using a gap-repair assay. A diverged chromosomal substrate was used as a repair template for the gapped plasmid, allowing mismatch-containing heteroduplex DNA (hDNA) formed during recombination to be monitored. Overall DSB repair efficiencies and the proportions of crossovers (COs) versus noncrossovers (NCOs) were determined in wild-type and helicase-defective strains, allowing the efficiency of CO and NCO production in each background to be calculated. In addition, the products of individual NCO events were sequenced to determine the location of hDNA. Because hDNA position is expected to differ depending on whether a NCO is produced by synthesis-dependent-strand-annealing (SDSA) or through a Holliday junction (HJ)-containing intermediate, its position allows the underlying molecular mechanism to be inferred. Results demonstrate that each helicase reduces the proportion of CO recombinants, but that each does so in a fundamentally different way. Mph1 does not affect the overall efficiency of gap repair, and its loss alters the CO-NCO by promoting SDSA at the expense of HJ-containing intermediates. By contrast, Sgs1 and Srs2 are each required for efficient gap repair, strongly promoting NCO formation and having little effect on CO efficiency. hDNA analyses suggest that all three helicases promote SDSA, and that Sgs1 and Srs2 additionally dismantle HJ-containing intermediates. The hDNA data are consistent with the proposed role of Sgs1 in the dissolution of double HJs, and we propose that Srs2 dismantles nicked HJs. © 2013 Mitchel et al.

Authors
Mitchel, K; Lehner, K; Jinks-Robertson, S
MLA Citation
Mitchel, K, Lehner, K, and Jinks-Robertson, S. "Heteroduplex DNA Position Defines the Roles of the Sgs1, Srs2, and Mph1 Helicases in Promoting Distinct Recombination Outcomes." PLoS Genetics 9.3 (2013).
PMID
23516370
Source
scival
Published In
PLoS genetics
Volume
9
Issue
3
Publish Date
2013
DOI
10.1371/journal.pgen.1003340

The mechanism of nucleotide excision repair-mediated UV-induced mutagenesis in nonproliferating cells

Following the irradiation of nondividing yeast cells with ultraviolet (UV) light, most induced mutations are inherited by both daughter cells, indicating that complementary changes are introduced into both strands of duplex DNA prior to replication. Early analyses demonstrated that such two-strand mutations depend on functional nucleotide excision repair (NER), but the molecular mechanism of this unique type of mutagenesis has not been further explored. In the experiments reported here, an ade2 adeX colonycolor system was used to examine the genetic control of UV-induced mutagenesis in nondividing cultures of Saccharomyces cerevisiae. We confirmed a strong suppression of two-strand mutagenesis in NER-deficient backgrounds and demonstrated that neither mismatch repair nor interstrand crosslink repair affects the production of these mutations. By contrast, proteins involved in the error-prone bypass of DNA damage (Rev3, Rev1, PCNA, Rad18, Pol32, and Rad5) and in the early steps of the DNA-damage checkpoint response (Rad17, Mec3, Ddc1, Mec1, and Rad9) were required for the production of two-strand mutations. There was no involvement, however, for the Pol h translesion synthesis DNA polymerase, the Mms2-Ubc13 postreplication repair complex, downstream DNA-damage checkpoint factors (Rad53, Chk1, and Dun1), or the Exo1 exonuclease. Our data support models in which UV-induced mutagenesis in nondividing cells occurs during the Pol z-dependent filling of lesion-containing, NER-generated gaps. The requirement for specific DNA-damage checkpoint proteins suggests roles in recruiting and/or activating factors required to fill such gaps. © 2013 by the Genetics Society of America.

Authors
Kozmin, SG; Jinks-Robertson, S
MLA Citation
Kozmin, SG, and Jinks-Robertson, S. "The mechanism of nucleotide excision repair-mediated UV-induced mutagenesis in nonproliferating cells." Genetics 193.3 (2013): 803-817.
PMID
23307894
Source
scival
Published In
Genetics
Volume
193
Issue
3
Publish Date
2013
Start Page
803
End Page
817
DOI
10.1534/genetics.112.147421

DNA repair mechanisms and the bypass of DNA damage in Saccharomyces cerevisiae

DNA repair mechanisms are critical for maintaining the integrity of genomic DNA, and their loss is associated with cancer predisposition syndromes. Studies in Saccharomyces cerevisiae have played a central role in elucidating the highly conserved mechanisms that promote eukaryotic genome stability. This review will focus on repair mechanisms that involve excision of a single strand from duplex DNA with the intact, complementary strand serving as a template to fill the resulting gap. These mechanisms are of two general types: those that remove damage from DNA and those that repair errors made during DNA synthesis. The major DNA-damage repair pathways are base excision repair and nucleotide excision repair, which, in the most simple terms, are distinguished by the extent of single-strand DNA removed together with the lesion. Mistakes made by DNA polymerases are corrected by the mismatch repair pathway, which also corrects mismatches generated when single strands of non-identical duplexes are exchanged during homologous recombination. In addition to the true repair pathways, the postreplication repair pathway allows lesions or structural aberrations that block replicative DNA polymerases to be tolerated. There are two bypass mechanisms: an error-free mechanism that involves a switch to an undamaged template for synthesis past the lesion and an error-prone mechanism that utilizes specialized translesion synthesis DNA polymerases to directly synthesize DNA across the lesion. A high level of functional redundancy exists among the pathways that deal with lesions, which minimizes the detrimental effects of endogenous and exogenous DNA damage. © 2013 by the Genetics Society of America.

Authors
Boiteux, S; Jinks-Robertson, S
MLA Citation
Boiteux, S, and Jinks-Robertson, S. "DNA repair mechanisms and the bypass of DNA damage in Saccharomyces cerevisiae." Genetics 193.4 (2013): 1025-1064.
PMID
23547164
Source
scival
Published In
Genetics
Volume
193
Issue
4
Publish Date
2013
Start Page
1025
End Page
1064
DOI
10.1534/genetics.112.145219

The 2013 Thomas Hunt Morgan Medal

The Genetics Society of America annually honors members who have made outstanding contributions to genetics. The Thomas Hunt Morgan Medal recognizes a lifetime contribution to the science of genetics. The Genetics Society of America Medal recognizes particularly outstanding contributions to the science of genetics over the past 32 years. The George W. Beadle Award recognizes distinguished service to the field of genetics and the community of geneticists. The Elizabeth W. Jones Award for Excellence in Education recognizes individuals or groups who have had a significant, sustained impact on genetics education at any level, from kindergarten through graduate school and beyond. The Novitski Prize recognizes an extraordinary level of creativity and intellectual ingenuity in solving significant problems in biological research through the application of genetic methods. We are pleased to announce the 2013 awards. © 2013 by the Genetics Society of America.

Authors
Petes, TD; Jinks-Robertson, S; Hieter, P
MLA Citation
Petes, TD, Jinks-Robertson, S, and Hieter, P. "The 2013 Thomas Hunt Morgan Medal." Genetics 194.1 (2013): 1-4.
PMID
23633133
Source
scival
Published In
Genetics
Volume
194
Issue
1
Publish Date
2013
Start Page
1
End Page
4
DOI
10.1534/genetics.113.150664

Removal of N-6-methyladenine by the nucleotide excision repair pathway triggers the repair of mismatches in yeast gap-repair intermediates

Gap-repair assays have been an important tool for studying the genetic control of homologous recombination in yeast. Sequence analysis of recombination products derived when a gapped plasmid is diverged relative to the chromosomal repair template additionally has been used to infer structures of strand-exchange intermediates. In the absence of the canonical mismatch repair pathway, mismatches present in these intermediates are expected to persist and segregate at the next round of DNA replication. In a mismatch repair defective (mlh1Δ) background, however, we have observed that recombination-generated mismatches are often corrected to generate gene conversion or restoration events. In the analyses reported here, the source of the aberrant mismatch removal during gap repair was examined. We find that most mismatch removal is linked to the methylation status of the plasmid used in the gap-repair assay. Whereas more than half of Dam-methylated plasmids had patches of gene conversion and/or restoration interspersed with unrepaired mismatches, mismatch removal was observed in less than 10% of products obtained when un-methylated plasmids were used in transformation experiments. The methylation-linked removal of mismatches in recombination intermediates was due specifically to the nucleotide excision repair pathway, with such mismatch removal being partially counteracted by glycosylases of the base excision repair pathway. These data demonstrate that nucleotide excision repair activity is not limited to bulky, helix-distorting DNA lesions, but also targets removal of very modest perturbations in DNA structure. In addition to its effects on mismatch removal, methylation reduced the overall gap-repair efficiency, but this reduction was not affected by the status of excision repair pathways. Finally, gel purification of DNA prior to transformation reduced gap-repair efficiency four-fold in a nucleotide excision repair-defective background, indicating that the collateral introduction of UV damage can potentially compromise genetic interpretations. © 2013 Elsevier B.V. All rights reserved.

Authors
Guo, X; Jinks-Robertson, S
MLA Citation
Guo, X, and Jinks-Robertson, S. "Removal of N-6-methyladenine by the nucleotide excision repair pathway triggers the repair of mismatches in yeast gap-repair intermediates." DNA Repair (2013).
Source
scival
Published In
DNA Repair
Publish Date
2013
DOI
10.1016/j.dnarep.2013.09.006

Transcription as a source of genome instability.

Alterations in genome sequence and structure contribute to somatic disease, affect the fitness of subsequent generations and drive evolutionary processes. The crucial roles of highly accurate replication and efficient repair in maintaining overall genome integrity are well-known, but the more localized stability costs that are associated with transcribing DNA into RNA molecules are less appreciated. Here we review the diverse ways in which the essential process of transcription alters the underlying DNA template and thereby modifies the genetic landscape.

Authors
Kim, N; Jinks-Robertson, S
MLA Citation
Kim, N, and Jinks-Robertson, S. "Transcription as a source of genome instability. (Published online)" Nat Rev Genet 13.3 (February 14, 2012): 204-214. (Review)
PMID
22330764
Source
pubmed
Published In
Nature Reviews Genetics
Volume
13
Issue
3
Publish Date
2012
Start Page
204
End Page
214
DOI
10.1038/nrg3152

Frameshift mutagenesis: The roles of primer- template misalignment and the nonhomologous end-joining pathway in Saccharomyces cerevisiae

Small insertions or deletions that alter the reading frame of a gene typically occur in simple repeats such as mononucleotide runs and are thought to reflect spontaneous primer-template misalignment d uring DNA replication. The resultingextrahelical repeat is efficiently recognized by the mismatch repair machinery, which specifically replaces the newly replicated strand to restore the original sequence. Frameshift mutagenesis is most easily studied using reversion assays, and previous studies in Saccharomyces cerevisiae suggested that the length threshold for polymerase slippage in mononucleotide runs is 4N. Because the probability of slippage is strongly correlated with run length, however, it was not clear whether shorter runs were unable to support slippage or whether the resulting frameshifts were obscured by the presence of longer runs. To address this issue, we removed all mononucleotide runs.3N from the yeast lys2ΔDBgl and lys2ΔA746 frameshift reversion assays, which detect net 1-bp deletions and insertions, respectively. Analyses demonstrate that 2N and 3N runs can support primer-template misalignment, but there is striking run-specific variation in the frequency of slippage, in the accumulation of +1 vs. 21 frameshifts and in the apparent efficiency of mismatch repair. We suggest that some of this variation reflects the role of flanking sequence in initiating primer-template misalignment and that some reflects replication-independent frameshifts generated by the nonhomologous end-joining pathway. Finally, we demonstrate that nonhomologous end joining is uniquely required for the de novo creation of tandem duplications from noniterated sequence. © 2012 by the Genetics Society of America.

Authors
Lehner, K; Mudrak, SV; Minesinger, BK; Jinks-Robertson, S
MLA Citation
Lehner, K, Mudrak, SV, Minesinger, BK, and Jinks-Robertson, S. "Frameshift mutagenesis: The roles of primer- template misalignment and the nonhomologous end-joining pathway in Saccharomyces cerevisiae." Genetics 190.2 (2012): 501-510.
PMID
22095081
Source
scival
Published In
Genetics
Volume
190
Issue
2
Publish Date
2012
Start Page
501
End Page
510
DOI
10.1534/genetics.111.134890

Formaldehyde-induced mutagenesis in Saccharomyces cerevisiae: Molecular properties and the roles of repair and bypass systems

Although DNA-protein cross-links (DPCs) pose a significant threat to genome stability, they remain a poorly understood class of DNA lesions. To define genetic impacts of DPCs on eukaryotic cells in molecular terms, we used a sensitive Saccharomyces cerevisiae frameshift-detection assay to analyze mutagenesis by formaldehyde (HCHO), and its response to nucleotide excision repair (NER) and translesion DNA synthesis (TLS). Brief exposure to HCHO was mutagenic for NER-defective rad14 strains but not for a corresponding RAD14 strain, nor for a rad14 strain lacking both Polζ and Polη TLS polymerases. This confirmed that HCHO-generated DNA lesions can trigger error-prone TLS and are substrates for the NER pathway. Sequencing revealed that HCHO-induced single-base-pair insertions occurred primarily at one hotspot; most of these insertions were also complex, changing an additional base-pair nearby. Most of the HCHO-induced mutations required both Polζ and Polη, providing a striking example of cooperativity between these two TLS polymerases during bypass of a DNA lesion formed in vivo. The similar molecular properties of HCHO-induced and spontaneous complex +1 insertions detected by this system suggest that DPCs which form in vivo during normal metabolism may contribute characteristic events to the spectra of spontaneous mutations in NER-deficient cells. © 2011 Elsevier B.V.

Authors
Grogan, D; Jinks-Robertson, S
MLA Citation
Grogan, D, and Jinks-Robertson, S. "Formaldehyde-induced mutagenesis in Saccharomyces cerevisiae: Molecular properties and the roles of repair and bypass systems." Mutation Research - Fundamental and Molecular Mechanisms of Mutagenesis 731.1-2 (2012): 92-98.
PMID
22197481
Source
scival
Published In
Mutation Research - Fundamental and Molecular Mechanisms of Mutagenesis
Volume
731
Issue
1-2
Publish Date
2012
Start Page
92
End Page
98
DOI
10.1016/j.mrfmmm.2011.12.004

The dCMP transferase activity of yeast Rev1 is biologically relevant during the bypass of endogenously generated AP sites.

The bypass of AP sites in yeast requires the Rev1 protein in addition to the Pol ζ translesion synthesis DNA polymerase. Although Rev1 was originally characterized biochemically as a dCMP transferase during AP-site bypass, the relevance of this activity in vivo is unclear. The current study uses highly sensitive frameshift- and nonsense-reversion assays to monitor the bypass of AP sites created when uracil is excised from chromosomal DNA. In the frameshift-reversion assay, an unselected base substitution frequently accompanies the selected mutation, allowing the relative incorporation of each of the four dNMPs opposite endogenously created AP sites to be inferred. Results with this assay suggest that dCMP is the most frequent dNMP inserted opposite uracil-derived AP sites and demonstrate that dCMP insertion absolutely requires the catalytic activity of Rev1. In the complementary nonsense-reversion assay, dCMP insertion likewise depended on the dCMP transferase activity of Rev1. Because dAMP insertion opposite uracil-derived AP sites does not revert the nonsense allele and hence could not be detected, it also was possible to detect low levels of dGMP or dTMP insertion upon loss of Rev1 catalytic activity. These results demonstrate that the catalytic activity of Rev1 is biologically relevant and is required specifically for dCMP insertion during the bypass of endogenous AP sites.

Authors
Kim, N; Mudrak, SV; Jinks-Robertson, S
MLA Citation
Kim, N, Mudrak, SV, and Jinks-Robertson, S. "The dCMP transferase activity of yeast Rev1 is biologically relevant during the bypass of endogenously generated AP sites." DNA Repair (Amst) 10.12 (December 10, 2011): 1262-1271.
PMID
22024240
Source
pubmed
Published In
DNA Repair
Volume
10
Issue
12
Publish Date
2011
Start Page
1262
End Page
1271
DOI
10.1016/j.dnarep.2011.09.017

Guanine repeat-containing sequences confer transcription-dependent instability in an orientation-specific manner in yeast.

Non-B DNA structures are a major contributor to the genomic instability associated with repetitive sequences. Immunoglobulin switch Mu (Sμ) region sequence is comprised of guanine-rich repeats and has high potential for forming G4 DNA, in which one strand of DNA folds into an array of guanine quartets. Taking advantage of the genetic tractability of Saccharomyces cerevisiae, we developed a recombination assay to investigate mechanisms involved in maintaining stability of G-rich repetitive sequence. By embedding Sμ sequence within recombination substrates under the control of a tetracycline-regulatable promoter, we demonstrate that the rate and orientation of transcription both affect the stability of Sμ sequence. In particular, the greatest instability was observed under high-transcription conditions when the Sμ sequence was oriented with the C-rich strand as the transcription template. The effect of transcription orientation was enhanced in the absence of the Type IB topoisomerase Top1, possibly due to enhanced R-loop formation. Loss of Sgs1 helicase and RNase H activity also increased instability, suggesting they may cooperatively function to reduce the formation of non-B DNA structures in highly transcribed regions. Finally, the Sμ sequence was unstable when transcription elongation was perturbed due to a defective THO complex. In a THO-deficient background, there was further exacerbation of orientation-dependent instability associated with the ectopically expressed, single-strand cytosine deaminase AID. The implications of our findings to understanding instability associated with potential G4 DNA forming sequences are discussed.

Authors
Kim, N; Jinks-Robertson, S
MLA Citation
Kim, N, and Jinks-Robertson, S. "Guanine repeat-containing sequences confer transcription-dependent instability in an orientation-specific manner in yeast." DNA Repair (Amst) 10.9 (September 5, 2011): 953-960.
PMID
21813340
Source
pubmed
Published In
DNA Repair
Volume
10
Issue
9
Publish Date
2011
Start Page
953
End Page
960
DOI
10.1016/j.dnarep.2011.07.002

Mutagenic processing of ribonucleotides in DNA by yeast topoisomerase I.

The ribonuclease (RNase) H class of enzymes degrades the RNA component of RNA:DNA hybrids and is important in nucleic acid metabolism. RNase H2 is specialized to remove single ribonucleotides [ribonucleoside monophosphates (rNMPs)] from duplex DNA, and its absence in budding yeast has been associated with the accumulation of deletions within short tandem repeats. Here, we demonstrate that rNMP-associated deletion formation requires the activity of Top1, a topoisomerase that relaxes supercoils by reversibly nicking duplex DNA. The reported studies extend the role of Top1 to include the processing of rNMPs in genomic DNA into irreversible single-strand breaks, an activity that can have distinct mutagenic consequences and may be relevant to human disease.

Authors
Kim, N; Huang, S-YN; Williams, JS; Li, YC; Clark, AB; Cho, J-E; Kunkel, TA; Pommier, Y; Jinks-Robertson, S
MLA Citation
Kim, N, Huang, S-YN, Williams, JS, Li, YC, Clark, AB, Cho, J-E, Kunkel, TA, Pommier, Y, and Jinks-Robertson, S. "Mutagenic processing of ribonucleotides in DNA by yeast topoisomerase I." Science 332.6037 (June 24, 2011): 1561-1564.
PMID
21700875
Source
pubmed
Published In
Science
Volume
332
Issue
6037
Publish Date
2011
Start Page
1561
End Page
1564
DOI
10.1126/science.1205016

Role for topoisomerase 1 in transcription-associated mutagenesis in yeast

High levels of transcription in Saccharomyces cerevisiae are associated with increased genetic instability, which has been linked to DNA damage. Here, we describe a pGAL-CAN1 forward mutation assay for studying transcription- associated mutagenesis (TAM) in yeast. In a wild-type background with no alterations in DNA repair capacity, ≈50% of forward mutations that arise in the CAN1 gene under high-transcription conditions are deletions of 2-5 bp. Furthermore, the deletions characteristic of TAM localize to discrete hotspots that coincide with 2-4 copies of a tandem repeat. Although the signature deletions of TAM are not affected by the loss of error-free or error-prone lesion bypass pathways, they are completely eliminated by deletion of the TOP1 gene, which encodes the yeast type IB topoisomerase. Hotspots can be transposed into the context of a frameshift reversion assay, which is sensitive enough to detect Top1-dependent deletions even in the absence of high transcription. We suggest that the accumulation of Top1 cleavage complexes is related to the level of transcription and that their removal leads to the signature deletions. Given the high degree of conservation between DNA metabolic processes, the links established here among transcription, Top1, and mutagenesis are likely to extend beyond the yeast system.

Authors
Lippert, MJ; Kimb, N; Cho, J-E; Larson, RP; Schoenly, NE; O'Shea, SH; Jinks-Robertson, S
MLA Citation
Lippert, MJ, Kimb, N, Cho, J-E, Larson, RP, Schoenly, NE, O'Shea, SH, and Jinks-Robertson, S. "Role for topoisomerase 1 in transcription-associated mutagenesis in yeast." Proceedings of the National Academy of Sciences of the United States of America 108.2 (2011): 698-703.
PMID
21177427
Source
scival
Published In
Proceedings of the National Academy of Sciences of USA
Volume
108
Issue
2
Publish Date
2011
Start Page
698
End Page
703
DOI
10.1073/pnas.1012363108

Abasic sites in the transcribed strand of yeast DNA are removed by transcription-coupled nucleotide excision repair.

Abasic (AP) sites are potent blocks to DNA and RNA polymerases, and their repair is essential for maintaining genome integrity. Although AP sites are efficiently dealt with through the base excision repair (BER) pathway, genetic studies suggest that repair also can occur via nucleotide excision repair (NER). The involvement of NER in AP-site removal has been puzzling, however, as this pathway is thought to target only bulky lesions. Here, we examine the repair of AP sites generated when uracil is removed from a highly transcribed gene in yeast. Because uracil is incorporated instead of thymine under these conditions, the position of the resulting AP site is known. Results demonstrate that only AP sites on the transcribed strand are efficient substrates for NER, suggesting the recruitment of the NER machinery by an AP-blocked RNA polymerase. Such transcription-coupled NER of AP sites may explain previously suggested links between the BER pathway and transcription.

Authors
Kim, N; Jinks-Robertson, S
MLA Citation
Kim, N, and Jinks-Robertson, S. "Abasic sites in the transcribed strand of yeast DNA are removed by transcription-coupled nucleotide excision repair." Mol Cell Biol 30.13 (July 2010): 3206-3215.
PMID
20421413
Source
pubmed
Published In
Molecular and Cellular Biology
Volume
30
Issue
13
Publish Date
2010
Start Page
3206
End Page
3215
DOI
10.1128/MCB.00308-10

Molecular structures of crossover and noncrossover intermediates during gap repair in yeast: implications for recombination.

The molecular structures of crossover (CO) and noncrossover (NCO) intermediates were determined by sequencing the products formed when a gapped plasmid was repaired using a diverged chromosomal template. Analyses were done in the absence of mismatch repair (MMR) to allow efficient detection of strand-transfer intermediates, and the results reveal striking differences in the extents and locations of heteroduplex DNA (hDNA) in NCO versus CO products. These data indicate that most NCOs are produced by synthesis-dependent strand annealing rather than by a canonical double-strand break repair pathway and that resolution of Holliday junctions formed as part of the latter pathway is highly constrained to generate CO products. We suggest a model in which the length of hDNA formed by the initiating strand invasion event determines susceptibility of the resulting intermediate to antirecombination and ultimately whether a CO- or a NCO-producing pathway is followed.

Authors
Mitchel, K; Zhang, H; Welz-Voegele, C; Jinks-Robertson, S
MLA Citation
Mitchel, K, Zhang, H, Welz-Voegele, C, and Jinks-Robertson, S. "Molecular structures of crossover and noncrossover intermediates during gap repair in yeast: implications for recombination." Mol Cell 38.2 (April 23, 2010): 211-222.
PMID
20417600
Source
pubmed
Published In
Molecular Cell
Volume
38
Issue
2
Publish Date
2010
Start Page
211
End Page
222
DOI
10.1016/j.molcel.2010.02.028

Seeking Resolution: Budding Yeast Enzymes Finally Make the Cut

Genetic studies reported in Molecular Cell (Ho et al., 2010) identify Mus81-Mms4 and Yen1 as the structure-specific endonucleases that cleave most Holliday junctions. A failure in this key step has profound effects on mitotic genome stability. © 2010 Elsevier Inc.

Authors
Jinks-Robertson, S
MLA Citation
Jinks-Robertson, S. "Seeking Resolution: Budding Yeast Enzymes Finally Make the Cut." Molecular Cell 40.6 (2010): 858-859.
Source
scival
Published In
Molecular Cell
Volume
40
Issue
6
Publish Date
2010
Start Page
858
End Page
859
DOI
10.1016/j.molcel.2010.12.001

dUTP incorporation into genomic DNA is linked to transcription in yeast.

Highly activated transcription is associated with eukaryotic genome instability, resulting in increased rates of mitotic recombination and mutagenesis. The association between high transcription and genome stability is probably due to a variety of factors including an enhanced accumulation of DNA damage, transcription-associated supercoiling, collision between replication forks and the transcription machinery, and the persistence of RNA-DNA hybrids. In the case of transcription-associated mutagenesis, we previously showed that there is a direct proportionality between the level of transcription and the mutation rate in the yeast Saccharomyces cerevisiae, and that the molecular nature of the mutations is affected by highly activated transcription. Here we show that the accumulation of apurinic/apyrimidinic sites is greatly enhanced in highly transcribed yeast DNA. We further demonstrate that most apurinic/apyrimidinic sites in highly transcribed DNA are derived from the removal of uracil, the presence of which is linked to direct incorporation of dUTP in place of dTTP. These results show an unexpected relationship between transcription and the fidelity of DNA synthesis, and raise intriguing cell biological issues with regard to nucleotide pool compartmentalization.

Authors
Kim, N; Jinks-Robertson, S
MLA Citation
Kim, N, and Jinks-Robertson, S. "dUTP incorporation into genomic DNA is linked to transcription in yeast." Nature 459.7250 (June 25, 2009): 1150-1153.
PMID
19448611
Source
pubmed
Published In
Nature
Volume
459
Issue
7250
Publish Date
2009
Start Page
1150
End Page
1153
DOI
10.1038/nature08033

The polymerase η translesion synthesis DNA polymerase acts independently of the mismatch repair system to limit mutagenesis caused by 7,8-dihydro-8-oxoguanine in yeast

Reactive oxygen species are ubiquitous mutagens that have been linked to both disease and aging. The most studied oxidative lesion is 7,8-dihydro-8-oxoguanine (GO), which is often miscoded during DNA replication, resulting specifically in GC → TA transversions. In yeast, the mismatch repair (MMR) system repairs GO · A mismatches generated during DNA replication, and the polymerase η (Polη) translesion synthesis DNA polymerase additionally promotes error-free bypass of GO lesions. It has been suggested that Polη limits GO-associated mutagenesis exclusively through its participation in the filling of MMR-generated gaps that contain GO lesions. In the experiments reported here, the SUP4-o forward-mutation assay was used to monitor GC → TA mutation rates in strains defective in MMR (Msh2 or Msh6) and/or in Polη activity. The results clearly demonstrate that Polη can function independently of the MMR system to prevent GO-associated mutations, presumably through preferential insertion of cytosine opposite replication-blocking GO lesions. Furthermore, the Polη-dependent bypass of GO lesions is more efficient on the lagging strand of replication and requires an interaction with proliferating cell nuclear antigen. These studies establish a new paradigm for the prevention of GO-associated mutagenesis in eukaryotes. Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Authors
Mudrak, SV; Welz-Voegele, C; Jinks-Robertson, S
MLA Citation
Mudrak, SV, Welz-Voegele, C, and Jinks-Robertson, S. "The polymerase η translesion synthesis DNA polymerase acts independently of the mismatch repair system to limit mutagenesis caused by 7,8-dihydro-8-oxoguanine in yeast." Molecular and Cellular Biology 29.19 (2009): 5316-5326.
PMID
19635811
Source
scival
Published In
Molecular and Cellular Biology
Volume
29
Issue
19
Publish Date
2009
Start Page
5316
End Page
5326
DOI
10.1128/MCB.00422-09

The mismatch repair system promotes DNA polymerase ζ-dependent translesion synthesis in yeast

DNA lesions that block replication can be bypassed by error-prone or error-free mechanisms. Error-prone mechanisms rely on specialized translesion synthesis (TLS) DNA polymerases that directly replicate over the lesion, whereas error-free pathways use an undamaged duplex as a template for lesion bypass. In the yeast Saccharomyces cerevisiae, most mutagenic TLS of spontaneous and induced DNA damage relies on DNA polymerase ζ (Polζ) activity. Here, we use a distinct mutational signature produced by Polζ in a frameshift-reversion assay to examine the role of the yeast mismatch repair (MMR) system in regulating Polζ-dependent mutagenesis. Whereas MMR normally reduces mutagenesis by removing errors introduced by replicative DNA polymerases, we find that the MMR system is required for Polζ-dependent mutagenesis. In the absence of homologous recombination, however, the errorprone Polζ pathway is not affected by MMR status. These results demonstrate that MMR promotes Polζ-dependent mutagenesis by inhibiting an alternative, error-free pathway that depends on homologous recombination. Finally, in contrast to its ability to remove mistakes made by replicative DNA polymerases, we show that MMR fails to efficiently correct errors introduced by Polζ.

Authors
Lehner, K; Jinks-Robertson, S
MLA Citation
Lehner, K, and Jinks-Robertson, S. "The mismatch repair system promotes DNA polymerase ζ-dependent translesion synthesis in yeast." Proceedings of the National Academy of Sciences of the United States of America 106.14 (2009): 5749-5754.
PMID
19307574
Source
scival
Published In
Proceedings of the National Academy of Sciences of USA
Volume
106
Issue
14
Publish Date
2009
Start Page
5749
End Page
5754
DOI
10.1073/pnas.0812715106

Role of proliferating cell nuclear antigen interactions in the mismatch repair-dependent processing of mitotic and meiotic recombination intermediates in yeast.

The mismatch repair (MMR) system is critical not only for the repair of DNA replication errors, but also for the regulation of mitotic and meiotic recombination processes. In a manner analogous to its ability to remove replication errors, the MMR system can remove mismatches in heteroduplex recombination intermediates to generate gene conversion events. Alternatively, such mismatches can trigger an MMR-dependent antirecombination activity that blocks the completion of recombination, thereby limiting interactions between diverged sequences. In Saccharomyces cerevisiae, the MMR proteins Msh3, Msh6, and Mlh1 interact with proliferating cell nuclear antigen (PCNA), and mutations that disrupt these interactions result in a mutator phenotype. In addition, some mutations in the PCNA-encoding POL30 gene increase mutation rates in an MMR-dependent manner. In the current study, pol30, mlh1, and msh6 mutants were used to examine whether MMR-PCNA interactions are similarly important during mitotic and meiotic recombination. We find that MMR-PCNA interactions are important for repairing mismatches formed during meiotic recombination, but play only a relatively minor role in regulating the fidelity of mitotic recombination.

Authors
Stone, JE; Ozbirn, RG; Petes, TD; Jinks-Robertson, S
MLA Citation
Stone, JE, Ozbirn, RG, Petes, TD, and Jinks-Robertson, S. "Role of proliferating cell nuclear antigen interactions in the mismatch repair-dependent processing of mitotic and meiotic recombination intermediates in yeast." Genetics 178.3 (March 2008): 1221-1236.
PMID
18245822
Source
pubmed
Published In
Genetics
Volume
178
Issue
3
Publish Date
2008
Start Page
1221
End Page
1236
DOI
10.1534/genetics.107.085415

Sequence divergence impedes crossover more than noncrossover events during mitotic gap repair in yeast

Homologous recombination between dispersed repeated sequences is important in shaping eukaryotic genome structure, and such ectopic interactions are affected by repeat size and sequence identity. A transformation-based, gap-repair assay was used to examine the effect of 2% sequence divergence on the efficiency of mitotic double-strand break repair templated by chromosomal sequences in yeast. Because the repaired plasmid could either remain autonomous or integrate into the genome, the effect of sequence divergence on the crossover-noncrossover (CO-NCO) outcome was also examined. Finally, proteins important for regulating the CO-NCO outcome and for enforcing identity requirements during recombination were examined by transforming appropriate mutant strains. Results demonstrate that the basic CO-NCO outcome is regulated by the Rad1-Rad10 endonuclease and the Sgs1 and Srs2 helicases, that sequence divergence impedes CO to a much greater extent than NCO events, that an intact mismatch repair system is required for the discriminating identical and nonidentical repair templates, and that the Sgs1 and Srs2 helicases play additional, antirecombination roles when the interacting sequences are not identical. Copyright © 2008 by the Genetics Society of America.

Authors
Welz-Voegele, C; Jinks-Robertson, S
MLA Citation
Welz-Voegele, C, and Jinks-Robertson, S. "Sequence divergence impedes crossover more than noncrossover events during mitotic gap repair in yeast." Genetics 179.3 (2008): 1251-1262.
PMID
18562664
Source
scival
Published In
Genetics
Volume
179
Issue
3
Publish Date
2008
Start Page
1251
End Page
1262
DOI
10.1534/genetics.108.090233

The effect of sequence context on spontaneous Polζ-dependent mutagenesis in Saccharomyces cerevisiae

The Polζ translesion synthesis (TLS) DNA polymerase is responsible for over 50% of spontaneous mutagenesis and virtually all damage-induced mutagenesis in yeast. We previously demonstrated that reversion of the lys2ΔA746 - 1 frameshift allele detects a novel type of +1 frameshift that is accompanied by one or more base substitutions and depends completely on the activity of Polζ. These 'complex' frameshifts accumulate at two discrete hotspots (HS1 and HS2) in the absence of nucleotide excision repair, and accumulate at a third location (HS3) in the additional absence of the translesion polymerase Polζ. The current study investigates the sequence requirements for accumulation of Polζ-dependent complex frameshifts at these hotspots. We observed that transposing 13 bp of identity from HS1 or HS3 to a new location within LYS2 was sufficient to recapitulate these hotspots. In addition, altering the sequence immediately upstream of HS2 had no effect on the activity of the hotspot. These data support a model in which misincorporation opposite a lesion precedes and facilitates the selected slippage event. Finally, analysis of nonsense mutation revertants indicates that Polζ can simultaneously introduce multiple base substitutions in the absence of an accompanying frameshift event. © 2008 The Author(s).

Authors
Abdulovic, AL; Minesinger, BK; Jinks-Robertson, S
MLA Citation
Abdulovic, AL, Minesinger, BK, and Jinks-Robertson, S. "The effect of sequence context on spontaneous Polζ-dependent mutagenesis in Saccharomyces cerevisiae." Nucleic Acids Research 36.6 (2008): 2082-2093.
PMID
18276637
Source
scival
Published In
Nucleic Acids Research
Volume
36
Issue
6
Publish Date
2008
Start Page
2082
End Page
2093
DOI
10.1093/nar/gkn054

Transcription-associated mutagenesis in yeast is directly proportional to the level of gene expression and influenced by the direction of DNA replication.

A high level of transcription has been associated with elevated spontaneous mutation and recombination rates in eukaryotic organisms. To determine whether the transcription level is directly correlated with the degree of genomic instability, we have developed a tetracycline-regulated LYS2 reporter system to modulate the transcription level over a broad range in Saccharomyces cerevisiae. We find that spontaneous mutation rate is directly proportional to the transcription level, suggesting that movement of RNA polymerase through the target initiates a mutagenic process(es). Using this system, we also investigated two hypotheses that have been proposed to explain transcription-associated mutagenesis (TAM): (1) transcription impairs replication fork progression in a directional manner and (2) DNA lesions accumulate under high-transcription conditions. The effect of replication fork progression was probed by comparing the mutational rates and spectra in yeast strains with the reporter gene placed in two different orientations near a well-characterized replication origin. The effect of endogenous DNA damage accumulation was investigated by studying TAM in strains defective in nucleotide excision repair or in lesion bypass by the translesion polymerase Polzeta. Our results suggest that both replication orientation and endogenous lesion accumulation play significant roles in TAM, particularly in terms of mutation spectra.

Authors
Kim, N; Abdulovic, AL; Gealy, R; Lippert, MJ; Jinks-Robertson, S
MLA Citation
Kim, N, Abdulovic, AL, Gealy, R, Lippert, MJ, and Jinks-Robertson, S. "Transcription-associated mutagenesis in yeast is directly proportional to the level of gene expression and influenced by the direction of DNA replication." DNA Repair (Amst) 6.9 (September 1, 2007): 1285-1296.
PMID
17398168
Source
pubmed
Published In
DNA Repair
Volume
6
Issue
9
Publish Date
2007
Start Page
1285
End Page
1296
DOI
10.1016/j.dnarep.2007.02.023

Identification of a strand-related bias in the PCNA-mediated bypass of spontaneous lesions by yeast Polη

Translesion synthesis (TLS) DNA polymerases are specialized to bypass lesions that block replicative polymerases and prevent complete genome duplication. Current TLS models hypothesize that PCNA, the polymerase processivity clamp, is important for regulating the access and loading of the low fidelity TLS polymerases onto DNA in response to replication-blocking lesions. PCNA binds to the C-terminus of yeast Polη, for example, and this interaction is required for cell survival after UV irradiation. Previously, we identified two spontaneous, Polζ-dependent "complex" mutation hotspots using the lys2ΔA746 frameshift reversion assay in repair-compromised cells. In the current study we observed an accumulation of Polζ-dependent complex frameshifts at a third hotspot in Polη-deficient cells. Interestingly, the sequence of this third hotspot is the reverse complement of the two hotspots previously identified, suggesting that the utilization of Polζ and Polη may be related to the position of the relevant lesion on either the leading- or lagging-strand template. Using the lys2ΔA746 assay system, we investigated changes in the accumulation of complex events at hotspots when the direction of replication was reversed in repair-compromised cells with either wildtype Polη, a deletion of Polη, or a mutant of Polη that cannot interact with PCNA. Our results suggest that there is a polymerase hierarchy between Polη and Polζ in the bypass of certain lesions and that the interaction of Polη with PCNA is needed for some, but not all, spontaneous lesion bypass. © 2007 Elsevier B.V. All rights reserved.

Authors
Abdulovic, AL; Minesinger, BK; Jinks-Robertson, S
MLA Citation
Abdulovic, AL, Minesinger, BK, and Jinks-Robertson, S. "Identification of a strand-related bias in the PCNA-mediated bypass of spontaneous lesions by yeast Polη." DNA Repair 6.9 (2007): 1307-1318.
PMID
17442629
Source
scival
Published In
DNA Repair
Volume
6
Issue
9
Publish Date
2007
Start Page
1307
End Page
1318
DOI
10.1016/j.dnarep.2007.02.026

Oligonucleotide transformation of yeast reveals mismatch repair complexes to be differentially active on DNA replication strands

Transformation of both prokaryotes and eukaryotes with single-stranded oligonucleotides can transfer sequence information from the oligonucleotide to the chromosome. We have studied this process using oligonucleotides that correct a -1 frameshift mutation in the LYS2 gene of Saccharomyces cerevisiae. We demonstrate that transformation by oligonucleotides occurs preferentially on the lagging strand of replication and is strongly inhibited by the mismatch-repair system. These results are consistent with a mechanism in which oligonucleotides anneal to single-stranded regions of DNA at a replication fork and serve as primers for DNA synthesis. Because the mispairs the primers create are efficiently removed by the mismatch-repair system, single-stranded oligonucleotides can be used to probe mismatch-repair function in a chromosomal context. Removal of mispairs created by annealing of the single-stranded oligonucleotides to the chromosomal DNA is as expected, with 7-nt loops being recognized solely by MutSβ and 1-nt loops being recognized by both MutSα and MutSβ. We also find evidence for Mlh1-independent repair of 7-nt, but not 1-nt, loops. Unexpectedly, we find a strand asymmetry of mismatch-repair function; transformation is blocked more efficiently by MutSα on the lagging strand of replication, whereas MutSβ does not show a significant strand bias. These results suggest an inherent strand-related difference in how the yeast MutSα and MutSβ complexes access and/or repair mismatches that arise in the context of DNA replication. © 2007 by The National Academy of Sciences of the USA.

Authors
Kow, YW; Bao, G; Reeves, JW; Jinks-Robertson, S; Crouse, GF
MLA Citation
Kow, YW, Bao, G, Reeves, JW, Jinks-Robertson, S, and Crouse, GF. "Oligonucleotide transformation of yeast reveals mismatch repair complexes to be differentially active on DNA replication strands." Proceedings of the National Academy of Sciences of the United States of America 104.27 (2007): 11352-11357.
PMID
17592146
Source
scival
Published In
Proceedings of the National Academy of Sciences of USA
Volume
104
Issue
27
Publish Date
2007
Start Page
11352
End Page
11357
DOI
10.1073/pnas.0704695104

Mutagenesis and the three R's in yeast

Mutagenesis is a prerequisite for evolution and also is an important contributor to human diseases. Most mutations in actively dividing cells originate during DNA replication as errors introduced when copying an undamaged DNA template or during the bypass of DNA lesions. In addition, mutations can be introduced during the repair of DNA double-strand breaks by either homologous recombination or non-homologous end-joining pathways. Finally, although generally considered to be a very high-fidelity process, the excision repair of DNA damage may be an important contributor to mutagenesis in non-dividing cells. In this review, we will discuss the well-known contributions of DNA replication to mutagenesis in Saccharomyces cerevisiae, as well as the less-appreciated contributions of recombination and repair to mutagenesis in this organism. © 2005 Elsevier B.V. All rights reserved.

Authors
Abdulovic, A; Kim, N; Jinks-Robertson, S
MLA Citation
Abdulovic, A, Kim, N, and Jinks-Robertson, S. "Mutagenesis and the three R's in yeast." DNA Repair 5.4 (2006): 409-421.
PMID
16412705
Source
scival
Published In
DNA Repair
Volume
5
Issue
4
Publish Date
2006
Start Page
409
End Page
421
DOI
10.1016/j.dnarep.2005.11.006

The in vivo characterization of translesion synthesis across UV-induced lesions in Saccharomyces cerevisiae: Insights into Polζ- and Polη-dependent frameshift mutagenesis

UV irradiation, a known carcinogen, induces the formation of dipyrimidine dimers with the predominant lesions being cyclobutane pyrimidine dimers (CPDs) and pyrimidine (6-4) pyrimidone adducts (6-4PPs). The relative roles of the yeast translesion synthesis DNA polymerases Polζ and Poη in UV survival and mutagenesis were examined using strains deficient in one or both polymerases. In addition, photoreactivation was used to specifically remove CPDs, thus allowing an estimate to be made of the relative contributions of CPDs vs. 6-4PPs to overall survival and mutagenesis. In terms of UV-induced mutagenesis, we focused on the +1 frameshift mutations detected by reversion of the lys2ΔA746 allele, as Polζ produces a distinct mutational signature in this assay. Results suggest that CPDs are responsible for most of the UV-associated toxicity as well as for the majority of UV-induced frameshift mutations in yeast. Although the presence of Polη generally suppresses UV-induced mutagenesis, our data suggest a role for this polymerase in generating some classes of +1 frameshifts. Finally, the examination of frameshift reversion spectra indicates a hierarchy between Polη and Polζ with respect to the bypass of UV-induced lesions. Copyright © 2006 by the Genetics Society of America.

Authors
Abdulovic, AL; Jinks-Robertson, S
MLA Citation
Abdulovic, AL, and Jinks-Robertson, S. "The in vivo characterization of translesion synthesis across UV-induced lesions in Saccharomyces cerevisiae: Insights into Polζ- and Polη-dependent frameshift mutagenesis." Genetics 172.3 (2006): 1487-1498.
PMID
16387871
Source
scival
Published In
Genetics
Volume
172
Issue
3
Publish Date
2006
Start Page
1487
End Page
1498
DOI
10.1534/genetics.105.052480

The effect of oxidative metabolism on spontaneous Polζ-dependent translesion synthesis in Saccharomyces cerevisiae

DNA lesions can stall or block high-fidelity polymerases, thus inhibiting replication. To bypass such lesions, low-fidelity translesion synthesis (TLS) polymerases can be used to insert a nucleotide across from the lesion or extend from a lesion:base mispair. When DNA repair is compromised in Saccharomyces cerevisiae, spontaneous DNA lesions can lead to a novel mutational event in which a frameshift is accompanied by one or more base pair substitutions. These "complex frameshifts" are dependent upon the TLS polymerase Polζ, and provide a mutational signature for mutagenic Polζ-dependent activity. In the current study, we have found that a specific subset of the Polζ-dependent mutational events requires oxidative metabolism. These results suggest that translesion bypass of spontaneously oxidized DNA bases can be a significant source of mutagenesis in repair compromised cells. © 2005 Elsevier B.V. All rights reserved.

Authors
Minesinger, BK; Abdulovic, AL; Ou, TM; Jinks-Robertson, S
MLA Citation
Minesinger, BK, Abdulovic, AL, Ou, TM, and Jinks-Robertson, S. "The effect of oxidative metabolism on spontaneous Polζ-dependent translesion synthesis in Saccharomyces cerevisiae." DNA Repair 5.2 (2006): 226-234.
PMID
16290107
Source
scival
Published In
DNA Repair
Volume
5
Issue
2
Publish Date
2006
Start Page
226
End Page
234
DOI
10.1016/j.dnarep.2005.10.002

Novel PMS1 alleles preferentially affect the repair of primer strand loops during DNA replication

Null mutations in DNA mismatch repair (MMR) genes elevate both base substitutions and insertions/deletions in simple sequence repeats. Data suggest that during replication of simple repeat sequences, polymerase slippage can generate single-strand loops on either the primer or template strand that are subsequently processed by the MMR machinery to prevent insertions and deletions, respectively. In the budding yeast Saccharomyces cerevisiae and mammalian cells, MMR appears to be more efficient at repairing mispairs comprised of loops on the template strand compared to loops on the primer strand. We identified two novel yeast pms1 alleles, pms1-G882E and pms1-H888R, which confer a strong defect in the repair of "primer strand" loops, while maintaining efficient repair of "template strand" loops. Furthermore, these alleles appear to affect equally the repair of 1-nucleotide primer strand loops during both leading- and lagging-strand replication. Interestingly, both pms1 mutants are proficient in the repair of 1-nucleotide loop mispairs in heteroduplex DNA generated during meiotic recombination. Our results suggest that the inherent inefficiency of primer strand loop repair is not simply a mismatch recognition problem but also involves Pms1 and other proteins that are presumed to function downstream of mismatch recognition, such as Mlh1. In addition, the findings reinforce the current view that during mutation avoidance, MMR is associated with the replication apparatus. Copyright © 2005, American Society for Microbiology. All Rights Reserved.

Authors
Erdeniz, N; Dudley, S; Gealy, R; Jinks-Robertson, S; Liskay, RM
MLA Citation
Erdeniz, N, Dudley, S, Gealy, R, Jinks-Robertson, S, and Liskay, RM. "Novel PMS1 alleles preferentially affect the repair of primer strand loops during DNA replication." Molecular and Cellular Biology 25.21 (2005): 9221-9231.
PMID
16227575
Source
scival
Published In
Molecular and Cellular Biology
Volume
25
Issue
21
Publish Date
2005
Start Page
9221
End Page
9231
DOI
10.1128/MCB.25.21.9221-9231.2005

Roles of RAD6 epistasis group members in spontaneous Polζ-dependent translesion synthesis in Saccharomyces cerevisiae

DNA lesions that arise during normal cellular metabolism can block the progress of replicative DNA polymerases, leading to cell cycle arrest and, in higher eukaryotes, apoptosis. Alternatively, such blocking lesions can be temporarily tolerated using either a recombination- or a translesion synthesis-based bypass mechanism. In Saccharomyces cerevisiae, members of the RAD6 epistasis group are key players in the regulation of lesion bypass by the translesion DNA polymerase Polζ. In this study, changes in the reversion rate and spectrum of the lys2ΔA746 -1 frameshift allele have been used to evaluate how the loss of members of the RAD6 epistasis group affects Polζ-dependent mutagenesis in response to spontaneous damage. Our data are consistent with a model in which Polζ-dependent mutagenesis relies on the presence of either Rad5 or Rad18, which promote two distinct error-prone pathways that partially overlap with respect to lesion specificity. The smallest subunit of Polδ, Pol32, is also required for Polζ-dependent spontaneous mutagenesis, suggesting a cooperative role between Polδ and Polζ for the bypass of spontaneous lesions. A third error-free pathway relies on the presence of Mms2, but may not require PCNA. Copyright © 2005 by the Genetics Society of America.

Authors
Minesinger, BK; Jinks-Robertson, S
MLA Citation
Minesinger, BK, and Jinks-Robertson, S. "Roles of RAD6 epistasis group members in spontaneous Polζ-dependent translesion synthesis in Saccharomyces cerevisiae." Genetics 169.4 (2005): 1939-1955.
PMID
15687278
Source
scival
Published In
Genetics
Volume
169
Issue
4
Publish Date
2005
Start Page
1939
End Page
1955
DOI
10.1534/genetics.104.033894

The 9-1-1 checkpoint clamp physically interacts with Polζ and is partially required for spontaneous Polζ-dependent mutagenesis in Saccharomyces cerevisiae

The use of translesion synthesis (TLS) polymerases to bypass DNA lesions during replication constitutes an important mechanism to restart blocked/stalled DNA replication forks. Because TLS polymerases generally have low fidelity on undamaged DNA, the cell must regulate the interaction of TLS polymerases with damaged versus undamaged DNA to maintain genome integrity. The Saccharomyces cerevisiae checkpoint proteins Ddc1, Rad17, and Mec3 form a clamp-like structure (the 9-1-1 clamp) that has physical similarity to the homotrimeric sliding clamp proliferating cell nuclear antigen, which interacts with and promotes the processivity of the replicative DNA polymerases. In this work, we demonstrate both an in vivo and in vitro physical interaction between the Mec3 and Ddc1 subunits of the 9-1-1 clamp and the Rev7 subunit of the Polζ TLS polymerase. In addition, we demonstrate that loss of Mec3, Ddc1, or Rad17 results in a decrease in Polζ-dependent spontaneous mutagenesis. These results suggest that, in addition to its check-point signaling role, the 9-1-1 clamp may physically regulate Polζ-dependent mutagenesis by controlling the access of Polζ to damaged DNA. © 2005 by The American Society for Biochemistry and Molecular Biology, Inc.

Authors
Sabbioneda, S; Minesinger, BK; Giannattasio, M; Plevani, P; Muzi-Falconi, M; Jinks-Robertson, S
MLA Citation
Sabbioneda, S, Minesinger, BK, Giannattasio, M, Plevani, P, Muzi-Falconi, M, and Jinks-Robertson, S. "The 9-1-1 checkpoint clamp physically interacts with Polζ and is partially required for spontaneous Polζ-dependent mutagenesis in Saccharomyces cerevisiae." Journal of Biological Chemistry 280.46 (2005): 38657-38665.
PMID
16169844
Source
scival
Published In
The Journal of biological chemistry
Volume
280
Issue
46
Publish Date
2005
Start Page
38657
End Page
38665
DOI
10.1074/jbc.M507638200

Mutagenic effects of abasic and oxidized abasic lesions in Saccharomyces cerevisiae

2-Deoxyribonolactone (L) and 2-deoxyribose (AP) are abasic sites that are produced by ionizing radiation, reactive oxygen species and a variety of DNA damaging agents. The biological processing of the AP site has been examined in the yeast Saccharomyces cerevisiae. However, nothing is known about how L is processed in this organism. We determined the bypass and mutagenic specificity of DNA containing an abasic site (AP and L) or the AP analog tetrahydrofuran (F) using an oligonucleotide transformation assay. The tetrahydrofuran analog and L were bypassed at 10-fold higher frequencies than the AP lesions. Bypass frequencies of lesions were greatly reduced in the absence of Rev1 or Polζ (rev3 mutant), but were only marginally reduced in the absence of Polν (rad30 mutant). Deoxycytidine was the preferred nucleotide inserted opposite an AP site whereas dA and dC were inserted at equal frequencies opposite F and L sites. In the rev1 and rev3 strains, dA was the predominant nucleotide inserted opposite these lesions. Overall, we conclude that both Rev1 and Polζ are required for the efficient bypass of abasic sites in yeast. © The Author 2005. Published by Oxford University Press. All rights reserved.

Authors
Kow, YW; Bao, G; Minesinger, B; Jinks-Robertson, S; Siede, W; Jiang, YL; Greenberg, MM
MLA Citation
Kow, YW, Bao, G, Minesinger, B, Jinks-Robertson, S, Siede, W, Jiang, YL, and Greenberg, MM. "Mutagenic effects of abasic and oxidized abasic lesions in Saccharomyces cerevisiae." Nucleic Acids Research 33.19 (2005): 6196-6202.
PMID
16257982
Source
scival
Published In
Nucleic Acids Research
Volume
33
Issue
19
Publish Date
2005
Start Page
6196
End Page
6202
DOI
10.1093/nar/gki926

Examination of the roles of Sgs1 and Srs2 helicases in the enforcement of recombination fidelity in Saccharomyces cerevisiae

Mutation in SGS1, which encodes the yeast homolog of the human Bloom helicase, or in mismatch repair (MMR) genes confers defects in the suppression of mitotic recombination between similar but nonidentical (homeologous) sequences. Mutational analysis of SGS1 suggests that the helicase activity is required for the suppression of both homologous and homeologous recombination and that the C-terminal 200 amino acids may be required specifically for the suppression of homeologous recombination. To clarify the mechanism by which the Sgs1 helicase enforces the fidelity of recombination, we examined the phenotypes associated with SGS1 deletion in MMR-defective and recombination-defective backgrounds. Deletion of SGS1 caused no additional loss of recombination fidelity above that associated with MMR defects, indicating that the suppression of homeologous recombination by Sgs1 may be dependent on MMR. However, the phenotype of the sgs1 rad51 mutant suggests a MMR-independent role of Sgs1 in the suppression of RAD51-independent recombination. While homologous recombination levels increase in sgs1Δ and in srs2Δ strains, the suppression of homeologous recombination was not relaxed in the srs2 mutant. Thus, although both Sgs1 and Srs2 limit the overall level of mitotic recombination, there are distinct differences in the roles of these helicases with respect to enforcement of recombination fidelity.

Authors
Spell, RM; Jinks-Robertson, S
MLA Citation
Spell, RM, and Jinks-Robertson, S. "Examination of the roles of Sgs1 and Srs2 helicases in the enforcement of recombination fidelity in Saccharomyces cerevisiae." Genetics 168.4 (2004): 1855-1865.
PMID
15611162
Source
scival
Published In
Genetics
Volume
168
Issue
4
Publish Date
2004
Start Page
1855
End Page
1865
DOI
10.1534/genetics.104.032771

Effects of mismatch repair and Hpr1 on transcription-stimulated mitotic recombination in the yeast Saccharomyces cerevisiae

High levels of transcription driven by the GAL1-10 promoter stimulate mitotic recombination between direct repeats (DR) as well as between substrates positioned on non-homologous chromosomes. When the substrates are on non-homologous chromosomes, transcription stimulates both gene conversion and crossover events, but the degree of the stimulation varies depending on which substrate is highly transcribed. In gene conversion assays where only one of the substrates is highly transcribed, the effect of transcribing the donor versus the recipient allele can be highly asymmetric. We have examined the basis of this asymmetry and demonstrate that it relates to the nature of the mismatch present in recombination intermediates and the presence of the Msh3 mismatch repair (MMR) protein. In addition to examining the asymmetry conferred by donor versus recipient allele transcription, the possible contribution of transcription elongation problems to transcription-stimulated recombination has been examined using hpr1 mutants. Hpr1 is important for efficient elongation through certain sequences, and in hpr1 mutants, elongation problems have been correlated with elevated recombination between direct repeats. As expected, we found that combining loss of Hpr1 with high levels of transcription had very strong synergistic effects on recombination rates between direct repeats. When the substrates were on non-homologous chromosomes, a weaker synergistic interaction between transcription and Hpr1 loss was observed in gene conversion assays, but only an additive relationship was observed in a crossover-specific assay. Although these data support a causal link between transcription elongation problems and elevated recombination rates, they also indicate that high levels of transcription can stimulate recombination by additional mechanisms. © 2004 Elsevier B.V. All rights reserved.

Authors
Freedman, JA; Jinks-Robertson, S
MLA Citation
Freedman, JA, and Jinks-Robertson, S. "Effects of mismatch repair and Hpr1 on transcription-stimulated mitotic recombination in the yeast Saccharomyces cerevisiae." DNA Repair 3.11 (2004): 1437-1446.
PMID
15380099
Source
scival
Published In
DNA Repair
Volume
3
Issue
11
Publish Date
2004
Start Page
1437
End Page
1446
DOI
10.1016/j.dnarep.2004.06.005

Identification of a distinctive mutation spectrum associated with high levels of transcription in yeast

High levels of transcription are associated with increased mutation rates in Saccharomyces cerevisiae, a phenomenon termed transcription-associated mutation (TAM). To obtain insight into the mechanism of TAM, we obtained LYS2 forward mutation spectra under low-versus high-transcription conditions in which LYS2 was expressed from either the low-level pLYS2 promoter or the strong pGAL1-10 promoter, respectively. Because of the large size of the LYS2 locus, forward mutations first were mapped to specific LYS2 subregions, and then those mutations that occurred within a defined 736-bp target region were sequenced. In the low-transcription strain base substitutions comprised the majority (64%) of mutations, whereas short insertion-deletion mutations predominated (56%) in the high-transcription strain. Most notably, deletions of 2 nucleotides (nt) comprised 21% of the mutations in the high-transcription strain, and these events occurred predominantly at 5′-(G/C)AAA-3′ sites. No -2 events were present in the low-transcription spectrum, thus identifying 2-nt deletions as a unique mutational signature for TAM.

Authors
Lippert, MJ; Freedman, JA; Barber, MA; Jinks-Robertson, S
MLA Citation
Lippert, MJ, Freedman, JA, Barber, MA, and Jinks-Robertson, S. "Identification of a distinctive mutation spectrum associated with high levels of transcription in yeast." Molecular and Cellular Biology 24.11 (2004): 4801-4809.
PMID
15143174
Source
scival
Published In
Molecular and Cellular Biology
Volume
24
Issue
11
Publish Date
2004
Start Page
4801
End Page
4809
DOI
10.1128/MCB.24.11.4801-4809.2004

Involvement of two endonuclease III homologs in the base excision repair pathway for the processing of DNA alkylation damage in Saccharomyces cerevisiae

DNA base excision repair (BER) is initiated by DNA glycosylases that recognize and remove damaged bases. The phosphate backbone adjacent to the resulting apurinic/apyrimidinic (AP) site is then cleaved by an AP endonuclease or glycosylase-associated AP lyase to invoke subsequent BER steps. We have used a genetic approach in Saccharomyces cerevisiae to determine whether or not AP sites are blocks to DNA replication and the biological consequences if AP sites persist in the genome. We previously reported that yeast cells deficient in the two AP endonucleases (apn1 apn2 double mutant) are extremely sensitive to killing by a model DNA alkylating agent methyl methanesulfonate (MMS) and that this sensitivity can be reduced by deleting the MAG1 3-methyladenine DNA glycosylase gene. Here we report that in the absence of the AP endonucleases, deletion of two Escherichia coli endonuclease III homologs, NTG1 and NTG2, partially suppresses MMS-induced killing, which indicates that the AP lyase products are deleterious unless they are further processed by an AP endonuclease. The severe MMS sensitivity seen in AP endonuclease deficient strains can also be rescued by treatment of cells with the AP lyase inhibitor methoxyamine, which suggests that the product of AP lyase action on an AP site is indeed an extremely toxic lesion. In addition to the AP endonuclease interactions, deletion of NTG1 and NTG2 enhances the mag1 mutant sensitivity to MMS, whereas overexpression of MAG1 in either the ntg1 or ntg2 mutant severely affects cell growth. These results help to delineate alkylation base lesion flow within the BER pathway. © 2003 Elsevier B.V. All rights reserved.

Authors
Hanna, M; Chow, BL; Morey, NJ; Jinks-Robertson, S; Doetsch, PW; Xiao, W
MLA Citation
Hanna, M, Chow, BL, Morey, NJ, Jinks-Robertson, S, Doetsch, PW, and Xiao, W. "Involvement of two endonuclease III homologs in the base excision repair pathway for the processing of DNA alkylation damage in Saccharomyces cerevisiae." DNA Repair 3.1 (2004): 51-59.
PMID
14697759
Source
scival
Published In
DNA Repair
Volume
3
Issue
1
Publish Date
2004
Start Page
51
End Page
59
DOI
10.1016/j.dnarep.2003.09.005

Determination of mitotic recombination rates by fluctuation analysis in Saccharomyces cerevisiae.

The study of recombination in Saccharomyces cerevisiae benefits from the availability of assay systems that select for recombinants, allowing the study of spontaneous events that represent natural assaults on the genome. However, the rarity of such spontaneous recombination requires selection of events that occur over many generations in a cell culture, and the number of recombinants increases exponentially following a recombination event. To avoid inflation of the average number of recombinants by jackpots arising from an event early in a culture, the distribution of the number of recombinants in independent cultures (fluctuation analysis) must be used to estimate the mean number of recombination events. Here we describe two statistical analyses (method of the median and the method of p0) to estimate the true mean of the number of events to be used to calculate the recombination rate. The use of confidence intervals to depict the error in such experiments is also discussed. The application of these methods is illustrated using the intron-based inverted repeat recombination reporter system developed in our lab to study the regulation of homeologous recombination.

Authors
Spell, RM; Jinks-Robertson, S
MLA Citation
Spell, RM, and Jinks-Robertson, S. "Determination of mitotic recombination rates by fluctuation analysis in Saccharomyces cerevisiae." Methods in molecular biology (Clifton, N.J.) 262 (2004): 3-12.
PMID
14769952
Source
scival
Published In
Methods in molecular biology (Clifton, N.J.)
Volume
262
Publish Date
2004
Start Page
3
End Page
12

Role of Mismatch Repair in the Fidelity of RAD51- and RAD59-Dependent Recombination in Saccharomyces cerevisiae

To prevent genome instability, recombination between sequences that contain mismatches (homeologous recombination) is suppressed by the mismatch repair (MMR) pathway. To understand the interactions necessary for this regulation, the genetic requirements for the inhibition of homeologous recombination were examined using mutants in the RAD52 epistasis group of Saccharomyces cerevisiae. The use of a chromosomal inverted-repeat recombination assay to measure spontaneous recombination between 91 and 100% identical sequences demonstrated differences in the fidelity of recombination in pathways defined by their dependence on RAD51 and RAD59. In addition, the regulation of homeologous recombination in rad51 and rad59 mutants displayed distinct patterns of inhibition by different members of the MMR pathway. Whereas the requirements for the MutS homolog, MSH2, and the MutL homolog, MLH1, in the suppression of homeologous recombination were similar in rad51 strains, the loss of MSH2 caused a greater loss in homeologous recombination suppression than did the loss of MLH1 in a rad59 strain. The nonequivalence of the regulatory patterns in the wild-type and mutant strains suggests an overlap between the roles of the RAD51 and RAD59 gene products in potential cooperative recombination mechanisms used in wild-type cells.

Authors
Spell, RM; Jinks-Robertson, S
MLA Citation
Spell, RM, and Jinks-Robertson, S. "Role of Mismatch Repair in the Fidelity of RAD51- and RAD59-Dependent Recombination in Saccharomyces cerevisiae." Genetics 165.4 (2003): 1733-1744.
PMID
14704162
Source
scival
Published In
Genetics
Volume
165
Issue
4
Publish Date
2003
Start Page
1733
End Page
1744

Delineating the requirements for spontaneous DNA damage resistance pathways in genome maintenance and viability in Saccharomyces cerevisiae

Cellular metabolic processes constantly generate reactive species that damage DNA. To counteract this relentless assault, cells have developed multiple pathways to resist damage. The base excision repair (BER) and nucleotide excision repair (NER) pathways remove damage whereas the recombination (REC) and postreplication repair (PRR) pathways bypass the damage, allowing deferred removal. Genetic studies in yeast indicate that these pathways can process a common spontaneous lesion (s), with mutational inactivation of any pathway increasing the burden on the remaining pathways. In this study, we examine the consequences of simultaneously compromising three or more of these pathways. Although the presence of a functional BER pathway alone is able to support haploid growth, retention of the NER, REC, or PRR pathway alone is not, indicating that BER is the key damage resistance pathway in yeast and may be responsible for the removal of the majority of either spontaneous DNA damage or specifically those lesions that are potentially lethal. In the diploid state, functional BER, NER, or REC alone can support growth, while PRR alone is insufficient for growth. In diploids, the presence of PRR alone may confer a lethal mutation load or, alternatively, PRR alone may be insufficient to deal with potentially lethal, replication-blocking lesions.

Authors
Morey, NJ; Doetsch, PW; Jinks-Robertson, S
MLA Citation
Morey, NJ, Doetsch, PW, and Jinks-Robertson, S. "Delineating the requirements for spontaneous DNA damage resistance pathways in genome maintenance and viability in Saccharomyces cerevisiae." Genetics 164.2 (2003): 443-455.
PMID
12807766
Source
scival
Published In
Genetics
Volume
164
Issue
2
Publish Date
2003
Start Page
443
End Page
455

Alleles of the yeast Pms1 mismatch-repair gene that differentially affect recombination- and replication-related processes.

Mismatch-repair (MMR) systems promote eukaryotic genome stability by removing errors introduced during DNA replication and by inhibiting recombination between nonidentical sequences (spellchecker and antirecombination activities, respectively). Following a common mismatch-recognition step effected by MutS-homologous Msh proteins, homologs of the bacterial MutL ATPase (predominantly the Mlh1p-Pms1p heterodimer in yeast) couple mismatch recognition to the appropriate downstream processing steps. To examine whether the processing steps in the spellchecker and antirecombination pathways might differ, we mutagenized the yeast PMS1 gene and screened for mitotic separation-of-function alleles. Two alleles affecting only the antirecombination function of Pms1p were identified, one of which changed an amino acid within the highly conserved ATPase domain. To more specifically address the role of ATP binding/hydrolysis in MMR-related processes, we examined mutations known to compromise the ATPase activity of Pms1p or Mlh1p with respect to the mitotic spellchecker and antirecombination activities and with respect to the repair of mismatches present in meiotic recombination intermediates. The results of these analyses confirm a differential requirement for the Pms1p ATPase activity in replication vs. recombination processes, while demonstrating that the Mlh1p ATPase activity is important for all examined MMR-related functions.

Authors
Welz-Voegele, C; Stone, JE; Tran, PT; Kearney, HM; Liskay, RM; Petes, TD; Jinks-Robertson, S
MLA Citation
Welz-Voegele, C, Stone, JE, Tran, PT, Kearney, HM, Liskay, RM, Petes, TD, and Jinks-Robertson, S. "Alleles of the yeast Pms1 mismatch-repair gene that differentially affect recombination- and replication-related processes." Genetics 162.3 (November 2002): 1131-1145.
PMID
12454061
Source
pubmed
Published In
Genetics
Volume
162
Issue
3
Publish Date
2002
Start Page
1131
End Page
1145

Base composition of mononucleotide runs affects DNA polymerase slippage and removal of frameshift intermediates by mismatch repair in Saccharomyces cerevisiae

The postreplicative mismatch repair (MMR) system is important for removing mutational intermediates that are generated during DNA replication, especially those that arise as a result of DNA polymerase slippage in simple repeats. Here, we use a forward mutation assay to systematically examine the accumulation of frameshift mutations within mononucleotide runs of variable composition in wild-type and MMR-defective yeast strains. These studies demonstrate that (i) DNA polymerase slippage occurs more often in 10-cytosine/10-guanine (10C/10G) runs than in 10-adenine/10-thymine (10A/10T) runs, (ii) the MMR system removes frameshift intermediates in 10A/10T runs more efficiently than in 10C/10G runs, (iii) the MMR system removes -1 frameshift intermediates more efficiently than +1 intermediates in all 10-nucleotide runs, and (iv) the repair specificities of the Msh2p-Msh3p and Msh2p-Msh6p mismatch recognition complexes with respect to 1-nucleotide insertion/deletion loops vary dramatically as a function of run composition. These observations are relevant to issues of genome stability, with both the rates and types of mutations that accumulate in mononucleotide runs being influenced by the primary sequence of the run as well as by the status of the MMR system.

Authors
Gragg, H; Harfe, BD; Jinks-Robertson, S
MLA Citation
Gragg, H, Harfe, BD, and Jinks-Robertson, S. "Base composition of mononucleotide runs affects DNA polymerase slippage and removal of frameshift intermediates by mismatch repair in Saccharomyces cerevisiae." Molecular and Cellular Biology 22.24 (2002): 8756-8762.
PMID
12446792
Source
scival
Published In
Molecular and Cellular Biology
Volume
22
Issue
24
Publish Date
2002
Start Page
8756
End Page
8762
DOI
10.1128/MCB.22.24.8756-8762.2002

Genetic requirements for spontaneous and transcription-stimulated mitotic recombination in Saccharomyces cerevisiae

The genetic requirements for spontaneous and transcription-stimulated mitotic recombination were determined using a recombination system that employs heterochromosomal lys2 substrates that can recombine only by crossover or only by gene conversion. The substrates were fused either to a constitutive low-level promoter (pLYS) or to a highly inducible promoter (pGAL). In the case of the "conversion-only" substrates the use of heterologous promoters allowed either the donor or the recipient allele to be highly transcribed. Transcription of the donor allele stimulated gene conversions in rad50, rad51, rad54, and rad59 mutants, but not in rad52, rad55, and rad57 mutants. In contrast, transcription of the recipient allele stimulated gene conversions in rad50, rad51, rad54, rad55, rad57, and rad59 mutants, but not in rad52 mutants. Finally, transcription stimulated crossovers in rad50, rad54, and rad59 mutants, but not in rad51, rad52, rad55, rad57 mutants. These data are considered in relation to previously proposed molecular mechanisms of transcription-stimulated recombination and in relation to the roles of the recombination proteins.

Authors
Freedman, JA; Jinks-Robertson, S
MLA Citation
Freedman, JA, and Jinks-Robertson, S. "Genetic requirements for spontaneous and transcription-stimulated mitotic recombination in Saccharomyces cerevisiae." Genetics 162.1 (2002): 15-27.
PMID
12242220
Source
scival
Published In
Genetics
Volume
162
Issue
1
Publish Date
2002
Start Page
15
End Page
27

The genome's best friend

DNA replication through mononucleotide runs is frequently associated with slippage of DNA polymerase, leading to the insertion or deletion of a small number of base pairs. A new study shows that, in the absence of DOG-1, a putative helicase, long poly(dG/C) runs are associated with deletions that extend into flanking DNA sequences. This mutational signature may be related to the ability of poly(dG) to form secondary structures such as G-quadruplex DNA, and may contribute to the genomic instability of tumor cells.

Authors
Jinks-Robertson, S
MLA Citation
Jinks-Robertson, S. "The genome's best friend." Nature Genetics 31.4 (2002): 331-332.
PMID
12101401
Source
scival
Published In
Nature Genetics
Volume
31
Issue
4
Publish Date
2002
Start Page
331
End Page
332
DOI
10.1038/ng936

Spontaneous frameshift mutations in saccharomyces cerevisiae: Accumulation during dna replication and removal by proofreading and mismatch repair activities

The accumulation of frameshift mutations during DNA synthesis is determined by the rate at which frameshift intermediates are generated during DNA polymerization and the efficiency with which frameshift intermediates are removed by DNA polymerase-associated exonucleolytic proofreading activity and/or the postreplicative mismatch repair machinery. To examine the relative contributions of these factors to replication fidelity in Saccharomyces cerevisiae, we determined the reversion rates and spectra of the lys2ΔBgl + 1 frameshift allele. Wild-type and homozygous mutant diploid strains with all possible combinations of defects in the exonuclease activities of DNA polymerases δ and ε (conferred by the pol3-01 and pol2-4 alleles, respectively) and in mismatch repair (deletion of MSH2) were analyzed. Although there was no direct correlation between homopolymer run length and frameshift accumulation in the wild-type strain, such a correlation was evident in the triple mutant strain lacking all repair capacity. Furthermore, examination of strains defective in one or two repair activities revealed distinct biases in the removal of the corresponding frameshift intermediates by exonucleolytic proofreading and/or mismatch repair. Finally, these analyses suggest that the mismatch repair machinery may be important for generating some classes of frameshift mutations in yeast.

Authors
Greene, CN; Jinks-Robertson, S
MLA Citation
Greene, CN, and Jinks-Robertson, S. "Spontaneous frameshift mutations in saccharomyces cerevisiae: Accumulation during dna replication and removal by proofreading and mismatch repair activities." Genetics 159.1 (2001): 65-75.
PMID
11560887
Source
scival
Published In
Genetics
Volume
159
Issue
1
Publish Date
2001
Start Page
65
End Page
75

Yeast base excision repair: Interconnections and networks

The removal of oxidative base damage from the genome of Saccharomyces cerevisiae is thought to occur primarily via the base excision repair (BER) pathway in a process initiated by several DNA N-glycosylase/AP lyases. We have found that yeast strains containing simultaneous multiple disruptions of BER genes are not hypersensitive to killing by oxidizing agents, but exhibit a spontaneous hyperrecombinogenic (hyper-rec) and mutator phenotype. The hyper-rec and mutator phenotypes are further enhanced by elimination of the nucleotide excision repair (NER) pathway. Furthermore, elimination of either the lesion bypass (REV3-dependent) or recombination (RAD52-dependent) pathway results in a further, specific enhancement of the hyper-rec or mutator phenotypes, respectively. Sensitivity (cell killing) to oxidizing agents is not observed unless multiple pathways are eliminated simultaneously. These data suggest that the BER, NER, recombination, and lesion bypass pathways have overlapping specificities in the removal of, or tolerance to, exogenous or spontaneous oxidative DNA damage in S. cerevisiae. Our results also suggest a physiological role for the AP lyase activity of certain BER N-glycosylases in vivo. © 2001.

Authors
Doetsch, PW; Morey, NJ; Swanson, RL; Jinks-Robertson, S
MLA Citation
Doetsch, PW, Morey, NJ, Swanson, RL, and Jinks-Robertson, S. "Yeast base excision repair: Interconnections and networks." Progress in Nucleic Acid Research and Molecular Biology 68 (2001): 29-39.
PMID
11554305
Source
scival
Published In
Progress in nucleic acid research and molecular biology
Volume
68
Publish Date
2001
Start Page
29
End Page
39

Mismatch repair proteins and mitotic genome stability

Mismatch repair (MMR) proteins play a critical role in maintaining the mitotic stability of eukaryotic genomes. MMR proteins repair errors made during DNA replication and in their absence, mutations accumulate at elevated rates. In addition, MMR proteins inhibit recombination between non-identical DNA sequences, and hence prevent genome rearrangements resulting from interactions between repetitive elements. This review provides an overview of the anti-mutator and anti-recombination functions of MMR proteins in the yeast Saccharomyces cerevisiae. Copyright (C) 2000 Elsevier Science B.V.

Authors
Harfe, BD; Jinks-Robertson, S
MLA Citation
Harfe, BD, and Jinks-Robertson, S. "Mismatch repair proteins and mitotic genome stability." Mutation Research - Fundamental and Molecular Mechanisms of Mutagenesis 451.1-2 (2000): 151-167.
PMID
10915870
Source
scival
Published In
Mutation Research - Fundamental and Molecular Mechanisms of Mutagenesis
Volume
451
Issue
1-2
Publish Date
2000
Start Page
151
End Page
167
DOI
10.1016/S0027-5107(00)00047-6

Stimulation of mitotic recombination events by high levels of RNA polymerase II transcription in yeast

The impact of high levels of RNA polymerase II transcription on mitotic recombination was examined using lys2 recombination substrates positioned on nonhomologous chromosomes. Substrates were used that could produce Lys+ recombinants by either a simple (noncrossover) gene conversion event or a crossover-associated recombination event, by only a simple gene conversion event, or by only a crossover event. Transcription of the lys2 substrates was regulated by the highly inducible GAL1-10 promoter or the low-level LYS2 promoter, with GAL1-10 promoter activity being controlled by the presence or absence of the Gal80p negative regulatory protein. Transcription was found to stimulate recombination in all assays used, but the level of stimulation varied depending on whether only one or both substrates were highly transcribed. In addition, there was an asymmetry in the types of recombination events observed when one substrate versus the other was highly transcribed. Finally, the lys2 substrates were positioned as direct repeats on the same chromosome and were found to exhibit a different recombinational response to high levels of transcription from that exhibited by the repeats on nonhomologous chromosomes. The relevance of these results to the mechanisms of transcription-associated recombination are discussed.

Authors
Saxe, D; Datta, A; Jinks-Robertson, S
MLA Citation
Saxe, D, Datta, A, and Jinks-Robertson, S. "Stimulation of mitotic recombination events by high levels of RNA polymerase II transcription in yeast." Molecular and Cellular Biology 20.15 (2000): 5404-5414.
PMID
10891481
Source
scival
Published In
Molecular and Cellular Biology
Volume
20
Issue
15
Publish Date
2000
Start Page
5404
End Page
5414
DOI
10.1128/MCB.20.15.5404-5414.2000

Discrete in vivo roles for the MutL homologs Mlh2p and Mlh3p in the removal of frameshift intermediates in budding yeast

The DNA mismatch repair machinery is involved in the correction of a wide variety of mutational intermediates. In bacterial cells, homodimers of the MutS protein bind mismatches and MutL homodimers couple mismatch recognition to downstream processing steps. Eukaryotes possess multiple MutS and MutL homologs that form discrete, heterodimeric complexes with specific mismatch recognition and repair properties. In yeast, there are six MutS (Msh1-6p) and four MutL (Mlh1-3p and Pms1p) family members. Heterodimers comprising Msh2p and Msh3p or Msh2p and Msh6p recognize mismatches in nuclear DNA and the subsequent processing steps most often involve a Mlh1 p-Pms1p heterodimer. Mlh1 p also forms heterodimeric complexes with Mlh2p and Mlh3p, and a minor role for Mlh3p in nuclear mismatch repair has been reported. No mismatch repair function has yet been assigned to the fourth yeast MutL homolog, Mlh2p, although mlh2 mutants exhibit weak resistance to some DNA damaging agents. We have used two frameshift reversion assays to examine the roles of the yeast Mlh2 and Mlh3 proteins in vivo. This analysis demonstrates, for the first time, that yeast Mlh2p plays a role in the repair of mutational intermediates, and extends earlier results implicating Mlh3p in mismatch repair.

Authors
Harfe, BD; Minesinger, BK; Jinks-Robertson, S
MLA Citation
Harfe, BD, Minesinger, BK, and Jinks-Robertson, S. "Discrete in vivo roles for the MutL homologs Mlh2p and Mlh3p in the removal of frameshift intermediates in budding yeast." Current Biology 10.3 (2000): 145-148.
PMID
10679328
Source
scival
Published In
Current Biology
Volume
10
Issue
3
Publish Date
2000
Start Page
145
End Page
148
DOI
10.1016/S0960-9822(00)00314-6

DNA polymerase ζ introduces multiple mutations when bypassing spontaneous DNA damage in Saccharomyces cerevisiae

Spontaneous DNA damage can be dealt with by multiple repair/bypass pathways that have overlapping specificities. We have used a frameshift reversion assay to examine spontaneous mutations that accumulate in yeast strains defective for the high-fidelity nucleotide excision repair or recombination pathways. In contrast to the simple frameshift mutations that occur in wild-type strains, the reversion events in mutant strains are often complex in nature, with the selected frameshift mutation being accompanied by one or more base substitutions. Genetic analyses demonstrate that the complex events are dependent on the Pol ζ translesion polymerase, thus implicating the DNA damage bypass activity of low-fidelity translesion polymerases in hypermutation phenomena.

Authors
Harfe, BD; Jinks-Robertson, S
MLA Citation
Harfe, BD, and Jinks-Robertson, S. "DNA polymerase ζ introduces multiple mutations when bypassing spontaneous DNA damage in Saccharomyces cerevisiae." Molecular Cell 6.6 (2000): 1491-1499.
PMID
11163221
Source
scival
Published In
Molecular Cell
Volume
6
Issue
6
Publish Date
2000
Start Page
1491
End Page
1499
DOI
10.1016/S1097-2765(00)00145-3

DNA mismatch repair and genetic instability

Mismatch repair (MMR) systems play a central role in promoting genetic stability by repairing DNA replication errors, inhibiting recombination between non-identical DNA sequences and participating in responses to DNA damage. The discovery of a link between human cancer and MMR defects has led to an explosion of research on eukaryotic MMR. The key proteins in MMR are highly conserved from bacteria to mammals, and this conservation has been critical for defining the components of eukaryotic MMR systems. In eukaryotes, there are multiple homologs of the key bacterial MutS and MutL MMR proteins, and these homologs form heterodimers that have discrete roles in MMR-related processes. This review describes the genetic and biochemical approaches used to study MMR, and summarizes the diverse roles that MMR proteins play in maintaining genetic stability.

Authors
Harfe, BD; Jinks-Robertson, S
MLA Citation
Harfe, BD, and Jinks-Robertson, S. "DNA mismatch repair and genetic instability." Annual Review of Genetics 34 (2000): 359-399.
PMID
11092832
Source
scival
Published In
Annual Review of Genetics
Volume
34
Publish Date
2000
Start Page
359
End Page
399
DOI
10.1146/annurev.genet.34.1.359

Regulation of mitotic homeologous recombination in yeast: Functions of mismatch repair and nucleotide excision repair genes

The Saccharomyces cerevisiae homologs of the bacterial mismatch repair proteins MutS and MutL correct replication errors and prevent recombination between homeologous (nonidentical) sequences. Previously, we demonstrated that Msh2p, Msh3p, and Pms1p regulate recombination between 91% identical inverted repeats, and here use the same substrates to show that Mlh1p and Msh6p have important antirecombination roles. In addition, substrates containing defined types of mismatches (base-base mismatches; 1-, 4-, or 12- nt insertion/deletion loops; or 18-nt palindromes) were used to examine recognition of these mismatches in mitotic recombination intermediates. Msh2p was required for recognition of all types of mismatches, whereas Msh6p recognized only base-base mismatches and 1-nt insertion/deletion loops. Msh3p was involved in recognition of the palindrome and all loops, but also had an unexpected antirecombination role when the potential heteroduplex contained only base-base mismatches. In contrast to their similar antimutator roles, Pms1p consistently inhibited recombination to a lesser degree than did Msh2p. In addition to the yeast MutS and MutL homologs, the exonuclease Exo1p and the nucleotide excision repair proteins Rad1p and Rad10p were found to have roles in inhibiting recombination between mismatched substrates.

Authors
Nicholson, A; Hendrix, M; Jinks-Robertson, S; Crouse, GF
MLA Citation
Nicholson, A, Hendrix, M, Jinks-Robertson, S, and Crouse, GF. "Regulation of mitotic homeologous recombination in yeast: Functions of mismatch repair and nucleotide excision repair genes." Genetics 154.1 (2000): 133-146.
PMID
10628975
Source
scival
Published In
Genetics
Volume
154
Issue
1
Publish Date
2000
Start Page
133
End Page
146

Genetic analysis of transcription-associated mutation in Saccharomyces cerevisiae

High levels of transcription are associated with elevated mutation rates in yeast, a phenomenon referred to as transcription-associated mutation (TAM). The transcription-associated increase in mutation rates was previously shown to be partially dependent on the Rev3p translesion bypass pathway, thus implicating DNA damage in TAM. In this study, we use reversion of a pGAL- driven lys2ΔBgl allele to further examine the genetic requirements of TAM. We find that TAM is increased by disruption of the nucleotide excision repair or recombination pathways. In contrast, elimination of base excision repair components has only modest effects on TAM. In addition to the genetic studies, the lys2ΔBgl reversion spectra of repair-proficient low and high transcription strains were obtained. In the low transcription spectrum, most of the frameshift events correspond to deletions of AT base pairs whereas in the high transcription strain, deletions of GC base pairs predominate. These results are discussed in terms of transcription and its role in DNA damage and repair.

Authors
Morey, NJ; Greene, CN; Jinks-Robertson, S
MLA Citation
Morey, NJ, Greene, CN, and Jinks-Robertson, S. "Genetic analysis of transcription-associated mutation in Saccharomyces cerevisiae." Genetics 154.1 (2000): 109-120.
PMID
10628973
Source
scival
Published In
Genetics
Volume
154
Issue
1
Publish Date
2000
Start Page
109
End Page
120

Sequence composition and context effects on the generation and repair of frameshift intermediates in mononucleotide runs in Saccharomyces cerevisiae

DNA polymerase slippage occurs frequently in tracts of a tandemly repeated nucleotide, and such slippage events can be genetically detected as frameshift mutations. In long mononucleotide runs, most frameshift intermediates are repaired by the postreplicative mismatch repair (MMR) machinery, rather than by the exonucleolytic proofreading activity of DNA polymerase. Although mononucleotide runs are hotspots for polymerase slippage events, it is not known whether the composition of a run and the surrounding context affect the frequency of slippage or the efficiency of MMR. To address these issues, 10-nucleotide (10N) runs were inserted into the yeast LYS2 gene to create +1 frameshift alleles. Slippage events within these runs were detected as Lys+ revertants. 10G or 10C runs were found to be more unstable than 10A or 10T runs, but neither the frequency of polymerase slippage nor the overall efficiency of MMR was greatly influenced by sequence context. Although complete elimination of MMR activity (msh2 mutants) affected all runs similarly, analyses of reversion rates in msh3 and msh6 mutants revealed distinct specificities of the yeast Msh2p-Msh3p and Msh2p-Msh6p mismatch binding complexes in the repair of frameshift intermediates in different sequence contexts.

Authors
Harfe, BD; Jinks-Robertson, S
MLA Citation
Harfe, BD, and Jinks-Robertson, S. "Sequence composition and context effects on the generation and repair of frameshift intermediates in mononucleotide runs in Saccharomyces cerevisiae." Genetics 156.2 (2000): 571-578.
PMID
11014807
Source
scival
Published In
Genetics
Volume
156
Issue
2
Publish Date
2000
Start Page
571
End Page
578

Saccharomyces cerevisiae Ntg1p and Ntg2p: Broad specificity N-glycosylases for the repair of oxidative DNA damage in the nucleus and mitochondria

Saccharomyces cerevisiae possesses two functional homologues (Ntg1p and Ntg2p) of the Escherichia coli endonuclease III protein, a DNA base excision repair N-glycosylase with a broad substrate specificity directed primarily against oxidatively damaged pyrimidines. The substrate specificites of Ntg1p and Ntg2p are similar but not identical, and differences in their amino acid sequences as well as inducibility by DNA damaging agents suggest that the two proteins may have different biological roles and subcellular locations. Experiments performed on oligonucleotides containing a variety of oxidative base damages indicated that dihydrothymine, urea, and uracil glycol are substrates for Ntg1p and Ntg2p, although dihydrothymine was a poor substrate for Ntg2p. Vectors encoding Ntg1p-green fluorescent protein (GFP) and Ntg2p-GFP fusions under the control of their respective endogenous promoters were utilized to observe the subcellular targeting of Ntg1p and Ntg2p in S. cerevisiae. Fluorescence microscopy of pNTG1-GFP and pNTG2-GFP transformants revealed that Ntg1p localizes primarily to the mitochondria with some nuclear localization, whereas Ntg2p localizes exclusively to the nucleus. In addition, the subcellular location of Ntg1p and Ntg2p confers differential sensitivities to the alkylating agent MMS. These results expand the known substrate specifities of Ntg1p and Ntg2p, indicating that their base damage recognition ranges show distinct differences and that these proteins mediate different roles in the repair of DNA base damage in the nucleus and mitochondria of yeast.

Authors
You, HJ; Swanson, RL; Harrington, C; Corbett, AH; Jinks-Robertson, S; Sentürker, S; Wallace, SS; Boiteux, S; Dizdaroglu, M; Doetsch, PW
MLA Citation
You, HJ, Swanson, RL, Harrington, C, Corbett, AH, Jinks-Robertson, S, Sentürker, S, Wallace, SS, Boiteux, S, Dizdaroglu, M, and Doetsch, PW. "Saccharomyces cerevisiae Ntg1p and Ntg2p: Broad specificity N-glycosylases for the repair of oxidative DNA damage in the nucleus and mitochondria." Biochemistry 38.35 (1999): 11298-11306.
PMID
10471279
Source
scival
Published In
Biochemistry
Volume
38
Issue
35
Publish Date
1999
Start Page
11298
End Page
11306
DOI
10.1021/bi991121i

Comparison of spontaneous and adaptive mutation spectra in yeast

Adaptive mutations occur in nongrowing populations of cells to overcome strong, nonlethal selection conditions. Several models have been proposed for the molecular mechanism(s) for this phenomenon in Escherichia coli, but the mechanisms involved in adaptive mutagenesis in the yeast Saccharomyces cerevisiae are largely unknown. We present here a comparison of the mutational spectra of spontaneous and adaptive frameshift reversion events in yeast. In contrast to results from E. coli, we find that the mutational spectrum of adaptive mutations in S. cerevisiae is not similar to that seen in mismatch repair defective cells, but rather resembles the spontaneous mutational events that occur during normal growth.

Authors
Greene, CN; Jinks-Robertson, S
MLA Citation
Greene, CN, and Jinks-Robertson, S. "Comparison of spontaneous and adaptive mutation spectra in yeast." Journal of Genetics 78.1 (1999): 51-55.
Source
scival
Published In
Journal of Genetics
Volume
78
Issue
1
Publish Date
1999
Start Page
51
End Page
55

Removal of frameshift intermediates by mismatch repair proteins in Saccharomyces cerevisiae

Frameshift mutations occur when the coding region of a gene is altered by addition or deletion of a number of base pairs that is not a multiple of three. The occurrence of a deletion versus an insertion type of frameshift depends on the nature of the transient intermediate structure formed during DNA synthesis. Extrahelical bases on the template strand give rise to deletions, whereas extrahelical bases on the strand being synthesized produce insertions. We previously used reversion of a +1 frameshift mutation to analyze the role of the mismatch repair (MMR) machinery in correcting -1 frameshift intermediates within a defined region of the yeast LYS2 gene. In this study, we have used reversion of a -1 frameshift mutation within the same region of LYS2 to analyze the role of the MMR machinery in the correction of frameshift intermediates that give rise to insertion events. We found that insertion and deletion events occur at similar rates but that the reversion spectra are very different in both the wild-type and MMR-defective backgrounds. In addition, analysis of the +1 spectra revealed novel roles for Msh3p and Msh6p in removing specific types of frameshift intermediates.

Authors
Harfe, BD; Jinks-Robertson, S
MLA Citation
Harfe, BD, and Jinks-Robertson, S. "Removal of frameshift intermediates by mismatch repair proteins in Saccharomyces cerevisiae." Molecular and Cellular Biology 19.7 (1999): 4766-4773.
PMID
10373526
Source
scival
Published In
Molecular and Cellular Biology
Volume
19
Issue
7
Publish Date
1999
Start Page
4766
End Page
4773

The role of the mismatch repair machinery in regulating mitotic and meiotic recombination between diverged sequences in yeast

Nonidentical recombination substrates recombine less efficiently than do identical substrates in yeast, and much of this inhibition can be attributed to action of the mismatch repair (MMR) machinery. In this study an intron- based inverted repeat assay system has been used to directly compare the rates of mitotic and meiotic recombination between pairs of 350-bp substrates varying from 82% to 100% in sequence identity. The recombination rate data indicate that sequence divergence impacts mitotic and meiotic recombination similarly, although subtle differences are evident. In addition to assessing recombination rates as a function of sequence divergence, the endpoints of mitotic and meiotic recombination events involving 94%-identical substrates were determined by DNA sequencing. The endpoint analysis indicates that the extent of meiotic heteroduplex DNA formed in a MMR-defective strain is 65% longer than that formed in a wild-type strain. These data are consistent with a model in which the MMR machinery interferes with the formation and/or extension of heteroduplex intermediates during recombination.

Authors
Chen, W; Jinks-Robertson, S
MLA Citation
Chen, W, and Jinks-Robertson, S. "The role of the mismatch repair machinery in regulating mitotic and meiotic recombination between diverged sequences in yeast." Genetics 151.4 (1999): 1299-1313.
PMID
10101158
Source
scival
Published In
Genetics
Volume
151
Issue
4
Publish Date
1999
Start Page
1299
End Page
1313

Overlapping specificities of base excision repair, nucleotide excision repair, recombination, and translesion synthesis pathways for DNA base damage in Saccharomyces cerevisiae

The removal of oxidative damage from Saccharomyces cerevisiae DNA is thought to be conducted primarily through the base excision repair pathway. The Escherichia coli endonuclease III homologs Ntg1p and Ntg2p are S. cerevisiae N-glycosylase-associated apurinic/apyrimidinic (AP) lyases that recognize a wide variety of damaged pyrimidines (H. J. You, R. L. Swanson, and P. W. Doetsch, Biochemistry 37:6033-6040, 1998). The biological relevance of the N-glycosylase-associated AP lyase activity in the repair of abasic sites is not well understood, and the majority of AP sites in Vivo are thought to be processed by Apn1p, the major AP endonuclease in yeast. We have found that yeast cells simultaneously lacking Ntg1p, Ntg2p, and Apn1p are hyperrecombinogenic (hyper-rec) and exhibit a mutator phenotype but are not sensitive to the oxidizing agents H2O2 and menadione. The additional disruption of the RAD52 gene in the ntg1 ntg2 apn1 triple mutant confers a high degree of sensitivity to these agents. The hyper-rec and mutator phenotypes of the ntg1 ntg2 apn1 triple mutant are further enhanced by the elimination of the nucleotide excision repair pathway. In addition, removal of either the lesion bypass (Rev3p-dependent) or recombination (Rad52p- dependent) pathway specifically enhances the hyper-rec or mutator phenotype, respectively. These data suggest that multiple pathways with overlapping specificities are involved in the removal of, or tolerance to, spontaneous DNA damage in S. cerevisiae. In addition, the fact that these responses to induced and spontaneous damage depend upon the simultaneous loss of Ntg1p, Ntg2p, and Apn1p suggests a physiological role for the AP lyase activity of Ntg1p and Ntg2p in vivo.

Authors
Swanson, RL; Morey, NJ; Doetsch, PW; Jinks-Robertson, S
MLA Citation
Swanson, RL, Morey, NJ, Doetsch, PW, and Jinks-Robertson, S. "Overlapping specificities of base excision repair, nucleotide excision repair, recombination, and translesion synthesis pathways for DNA base damage in Saccharomyces cerevisiae." Molecular and Cellular Biology 19.4 (1999): 2929-2935.
PMID
10082560
Source
scival
Published In
Molecular and Cellular Biology
Volume
19
Issue
4
Publish Date
1999
Start Page
2929
End Page
2935

Mismatch repair proteins regulate heteroduplex formation during mitotic recombination in yeast

Mismatch repair (MMR) proteins actively inhibit recombination between diverged sequences in both prokaryotes and eukaryotes. Although the molecular basis of the antirecombination activity exerted by MMR proteins is unclear, it presumably involves the recognition of mismatches present in heteroduplex recombination intermediates. This recognition could be exerted during the initial stage of strand exchange, during the extension of heteroduplex DNA, or during the resolution of recombination intermediates. We previously used an assay system based on 350-bp inverted-repeat substrates to demonstrate that MMR proteins strongly inhibit mitotic recombination between diverged sequences in Saccharomyces cerevisiae. The assay system detects only those events that reverse the orientation of the region between the recombination substrates, which can occur as a result of either intrachromatid crossover or sister chromatid conversion. In the present study we sequenced the products of mitotic recombination between 94%-identical substrates in order to map gene conversion tracts in wild-type versus MMR-defective yeast strains. The sequence data indicate that (i) most recombination occurs via sister chromatid conversion and (ii) gene conversion tracts in an MMR-defective strain are significantly longer than those in an isogenic wild-type strain. The shortening of conversion tracts observed in a wild-type strain relative to an MMR-defective strain suggests that at least part of the antirecombination activity of MMR proteins derives from the blockage of heteroduplex extension in the presence of mismatches.

Authors
Chen, W; Jinks-Robertson, S
MLA Citation
Chen, W, and Jinks-Robertson, S. "Mismatch repair proteins regulate heteroduplex formation during mitotic recombination in yeast." Molecular and Cellular Biology 18.11 (1998): 6525-6537.
PMID
9774668
Source
scival
Published In
Molecular and Cellular Biology
Volume
18
Issue
11
Publish Date
1998
Start Page
6525
End Page
6537

Genetic control of microsatellite stability.

Authors
Sia, EA; Jinks-Robertson, S; Petes, TD
MLA Citation
Sia, EA, Jinks-Robertson, S, and Petes, TD. "Genetic control of microsatellite stability." Mutat Res 383.1 (January 31, 1997): 61-70. (Review)
PMID
9042420
Source
pubmed
Published In
Mutation Research - Fundamental and Molecular Mechanisms of Mutagenesis
Volume
383
Issue
1
Publish Date
1997
Start Page
61
End Page
70

Dual roles for DNA sequence identity and the mismatch repair system in the regulation of mitotic crossing-over in yeast

Sequence divergence acts as a potent barrier to homologous recombination; much of this barrier derives from an antirecombination activity exerted by mismatch repair proteins. An inverted repeat assay system with recombination substrates ranging in identity from 74% to 100% has been used to define the relationship between sequence divergence and the rate of mitotic crossing-over in yeast. To elucidate the role of the mismatch repair machinery in regulating recombination between mismatched substrates, we performed experiments in both wild-type and mismatch repair defective strains. We find that a single mismatch is sufficient to inhibit recombination between otherwise identical sequences, and that this inhibition is dependent on the mismatch repair system. Additional mismatches have a cumulative negative effect on the recombination rate. With sequence divergence of up to approximately 10%, the inhibitory effect of mismatches results mainly from antirecombination activity of the mismatch repair system. With greater levels of divergence, recombination is inefficient even in the absence of mismatch repair activity. In both wild-type and mismatch repair defective strains, an approximate log-linear relationship is observed between the recombination rate and the level of sequence divergence.

Authors
Datta, A; Hendrix, M; Lipsitch, M; Jinks-Robertson, S
MLA Citation
Datta, A, Hendrix, M, Lipsitch, M, and Jinks-Robertson, S. "Dual roles for DNA sequence identity and the mismatch repair system in the regulation of mitotic crossing-over in yeast." Proceedings of the National Academy of Sciences of the United States of America 94.18 (1997): 9757-9762.
PMID
9275197
Source
scival
Published In
Proceedings of the National Academy of Sciences of USA
Volume
94
Issue
18
Publish Date
1997
Start Page
9757
End Page
9762
DOI
10.1073/pnas.94.18.9757

Meiotic crossing over between nonhomologous chromosomes affects chromosome segregation in yeast

Meiotic recombination between artificial repeats positioned on nonhomologous chromosomes occurs efficiently in the yeast Saccharomyces cerevisiae. Both gene conversion and crossover events have been observed, with crossovers yielding reciprocal translocations. In the current study, 5.5-kb ura3 repeats positioned on chromosomes V and XV were used to examine the effect of ectopic recombination on meiotic chromosome segregation. Ura random spores were selected and gene conversion vs. crossover events were distinguished by Southern blot analysis. Approximately 15% of the crossover events between chromosomes V and XV were associated with missegregation of one of these chromosomes. The missegregation was manifest as hyperploid spores containing either both translocations plus a normal chromosome, or both normal chromosomes plus one of the translocations. In those cases where it could be analyzed, missegregration occurred at the first meiotic division. These data are discussed in terms of a model in which ectopic crossovers compete efficiently with normal allelic crossovers in directing meiotic chromosome segregation.

Authors
Jinks-Robertson, S; Sayeed, S; Murphy, T
MLA Citation
Jinks-Robertson, S, Sayeed, S, and Murphy, T. "Meiotic crossing over between nonhomologous chromosomes affects chromosome segregation in yeast." Genetics 146.1 (1997): 69-78.
PMID
9136001
Source
scival
Published In
Genetics
Volume
146
Issue
1
Publish Date
1997
Start Page
69
End Page
78

Frameshift intermediates in homopolymer runs are removed efficiently by yeast mismatch repair proteins

A change in the number of base pairs within a coding sequence can result in a frameshift mutation, which almost invariably eliminates the function of the encoded protein. A frameshift reversion assay with Saccharomyces cerevisiae that can be used to examine the types of insertions and deletions that are generated during DNA replication, as well as the editing functions that remove such replication errors, has been developed. Reversion spectra have been obtained in a wild-type strain and in strains defective for defined components of the postreplicative mismatch repair system (msh2, msh3, msh6, msh3 msh6, pms1, and mlh1 mutants). Comparison of the spectra reveals that yeast mismatch repair proteins preferentially remove frameshift intermediates that arise in homopolymer tracts and indicates that some of the proteins have distinct substrate or context specificities.

Authors
Greene, CN; Jinks-Robertson, S
MLA Citation
Greene, CN, and Jinks-Robertson, S. "Frameshift intermediates in homopolymer runs are removed efficiently by yeast mismatch repair proteins." Molecular and Cellular Biology 17.5 (1997): 2844-2850.
PMID
9111356
Source
scival
Published In
Molecular and Cellular Biology
Volume
17
Issue
5
Publish Date
1997
Start Page
2844
End Page
2850

Destabilization of simple repetitive DNA sequences by transcription in yeast.

Simple repetitive DNA sequences in the eukaryotic genome frequently alter in length. In wild-type strains, we find that transcription through a repetitive poly GT tract destabilizes the tract four- to ninefold. In mismatch repair-deficient yeast strains, simple repeats are very unstable. High levels of transcription in such strains destabilize repetitive tracts an additional two- to threefold.

Authors
Wierdl, M; Greene, CN; Datta, A; Jinks-Robertson, S; Petes, TD
MLA Citation
Wierdl, M, Greene, CN, Datta, A, Jinks-Robertson, S, and Petes, TD. "Destabilization of simple repetitive DNA sequences by transcription in yeast." Genetics 143.2 (June 1996): 713-721.
PMID
8725221
Source
pubmed
Published In
Genetics
Volume
143
Issue
2
Publish Date
1996
Start Page
713
End Page
721

Mitotic crossovers between diverged sequences are regulated by mismatch repair proteins in Saccharomyces cerevisiae

Mismatch repair systems correct replication and recombination-associated mispaired bases and influence the stability of simple repeats. These systems thus serve multiple roles in maintaining genetic stability in eukaryotes, and human mismatch repair defects have been associated with hereditary predisposition to cancer. In prokaryotes, mismatch repair systems also have been shown to limit recombination between diverged (homeologous) sequences. We have developed a unique intron-based assay system to examine the effects of yeast mismatch repair genes (PMS1, MSH2, and MSH3) on crossovers between homeologous sequences. We find that the apparent antirecombination effects of mismatch repair proteins in mitosis are related to the degree of substrate divergence. Defects in mismatch repair can elevate homeologous recombination between 91% homologous substrates as much as 100-fold while having only modest effects on recombination between 77% homologous substrates. These observations have implications for genome stability and general mechanisms of recombination in eukaryotes.

Authors
Datta, A; Adjiri, A; New, L; Crouse, GF; Jinks-Robertson, S
MLA Citation
Datta, A, Adjiri, A, New, L, Crouse, GF, and Jinks-Robertson, S. "Mitotic crossovers between diverged sequences are regulated by mismatch repair proteins in Saccharomyces cerevisiae." Molecular and Cellular Biology 16.3 (1996): 1085-1093.
PMID
8622653
Source
scival
Published In
Molecular and Cellular Biology
Volume
16
Issue
3
Publish Date
1996
Start Page
1085
End Page
1093

Association of increased spontaneous mutation rates with high levels of transcription in yeast

Complex processes such as transcription, replication, repair, and recombination require changes in chromatin structure and the interactions of numerous trans-acting factors with DNA sequences, raising the possibility that these processes may be interrelated. Here the effect of transcription on the rate of spontaneous mutation in the yeast Saccharomyces cerevisiae was examined. With the use of a lys2 frameshift allele under the control of a highly inducible promoter, the rate of spontaneous reversion was shown to increase when the mutant gene was highly transcribed. Thus, transcriptionally active DNA and enhanced spontaneous mutation rates are associated in yeast.

Authors
Datta, A; Jinks-Robertson, S
MLA Citation
Datta, A, and Jinks-Robertson, S. "Association of increased spontaneous mutation rates with high levels of transcription in yeast." Science 268.5217 (1995): 1616-1619.
PMID
7777859
Source
scival
Published In
Science
Volume
268
Issue
5217
Publish Date
1995
Start Page
1616
End Page
1619

Experimental determination of rates of concerted evolution.

Authors
Jinks-Robertson, S; Petes, TD
MLA Citation
Jinks-Robertson, S, and Petes, TD. "Experimental determination of rates of concerted evolution." Methods Enzymol 224 (1993): 631-646.
PMID
8264416
Source
pubmed
Published In
Methods in Enzymology
Volume
224
Publish Date
1993
Start Page
631
End Page
646

A yeast expression system for human galactose-1-phosphate uridylyltransferase

Galactose-1-phosphate uridylyltransferase (GALT) (UTP:α-D-hexose-1 -phosphate uridylyltransferase, EC 2.7.7.10) is an essential enzyme of the Leloir pathway of galactose metabolism. Mutations in human GALT are associated with the potentially lethal disorder galactosemia, which affects 1 in 30,000-60,000 live-born infants. Although a number of base substitutions have been identified in the GALT alleles of galactosemia patients, the detailed biochemical impact of these mutations on GALT enzymatic activity remains obscure. Similarly, little is known about the sequence/structure/function relationships for wild-type human GALT. As a first step toward addressing these questions, we have developed a yeast-based expression system for the human enzyme. The wild-type human GALT coding sequence has been introduced into a strain of Saccharomyces cerevisiae that carries a disruption of the GALT-encoding GAL7 gene and, therefore, expresses no endogenous GALT. Transformants were tested for restoration of GALT activity both indirectly, by cell growth on galactose, and directly, by analysis of enzyme activity in cell extracts. The results of both tests were striking; wild-type human GALT functioned in yeast almost as well as the endogenous enzyme. In contrast, cells transformed with either human or yeast GALT sequences engineered to carry a common human GALT mutation, Q188R (changing Gln188 to Arg), exhibited essentially no detectable GALT activity and failed to grow on galactose. Lymphoblasts from patients homozygous for the Q188R mutation similarly exhibited essentially no detectable GALT activity in parallel assays. The results reported here establish the utility of the yeast-based expression system for human GALT and set the stage for more detailed studies of this important enzyme and its role in galactosemia.

Authors
Fridovich-Keil, JL; Jinks-Robertson, S
MLA Citation
Fridovich-Keil, JL, and Jinks-Robertson, S. "A yeast expression system for human galactose-1-phosphate uridylyltransferase." Proceedings of the National Academy of Sciences of the United States of America 90.2 (1993): 398-402.
PMID
8421669
Source
scival
Published In
Proceedings of the National Academy of Sciences of the United States of America
Volume
90
Issue
2
Publish Date
1993
Start Page
398
End Page
402
DOI
10.1073/pnas.90.2.398

Time-dependent mitotic recombination in Saccharomyces cerevisiae

The time-dependent appearance of prototrophic recombinants between heterologously located artificial repeats has been studied in Saccharomyces cerevisiae. While initial prototrophic colony numbers from independent cultures were highly variable, additional recombinants were found to arise daily at roughly constant rates irrespective of culture. These late-appearing recombinants could be accounted for neither by detectable growth on the selective media nor by delayed appearance of recombinants present at the time of selective plating. Significantly, at no time did the distributions of recombinants fully match those expected according to the Luria-Delbruck model and, in fact, after the first day, the distributions much more closely approximated a Poisson distribution. Prototrophic recombinants accumulated not only on the relevant selective medium, but also on media unrelated to the acquired prototrophy.

Authors
Steele, DF; Jinks-Robertson, S
MLA Citation
Steele, DF, and Jinks-Robertson, S. "Time-dependent mitotic recombination in Saccharomyces cerevisiae." Current Genetics 23.5-6 (1993): 423-429.
PMID
8319298
Source
scival
Published In
Current Genetics
Volume
23
Issue
5-6
Publish Date
1993
Start Page
423
End Page
429

Substrate length requirements for efficient mitotic recombination in Saccharomyces cerevisiae

An ectopic recombination system using ura3 heteroalleles varying in size from 80 to 960 bp has been used to examine the effect of substrate length on spontaneous mitotic recombination. The ura3 heteroalleles were positioned either on nonhomologous chromosomes (heterochromosomal repeats) or as direct or inverted repeats on the same chromosome (intrachromosomal repeats). While the intrachromosomal events occur at rates at least 2 orders of magnitude greater than the corresponding heterochromosomal events, the recombination rate for each type of repeat considered separately exhibits a linear dependence on substrate length. The linear relationships allow estimation of the corresponding minimal efficient processing segments, which are approximately 250 bp regardless of the relative positions of the repeats in the yeast genome. An examination of the distribution of recombination events into simple gene conversion versus crossover events indicates that reciprocal exchange is more sensitive to substrate size than is gene conversion.

Authors
Jinks-Robertson, S; Michelitch, M; Ramcharan, S
MLA Citation
Jinks-Robertson, S, Michelitch, M, and Ramcharan, S. "Substrate length requirements for efficient mitotic recombination in Saccharomyces cerevisiae." Molecular and Cellular Biology 13.7 (1993): 3937-3950.
PMID
8321201
Source
scival
Published In
Molecular and Cellular Biology
Volume
13
Issue
7
Publish Date
1993
Start Page
3937
End Page
3950

An examination of adaptive reversion in Saccharomyces cerevisiae

Reversion to Lys+ prototrophy in a haploid yeast strain containing a defined lys2 frameshift mutation has been examined. When cells were plated on synthetic complete medium lacking only lysine, the numbers of Lys+ revertant colonies accumulated in a time-dependent manner in the absence of any detectable increase in cell number. An examination of the distribution of the numbers of early appearing Lys+ colonies from independent cultures suggests that the mutations to prototrophy occurred randomly during nonselective growth. In contrast, an examination of the distribution of late appearing Lys+ colonies indicates that the underlying reversion events occurred after selective plating. No accumulation of Lys+ revertants occurred when cells were starved for tryptophan, leucine or both lysine and tryptophan prior to plating selectively for Lys+ revertants. These results indicate that mutations accumulate more frequently when they confer a selective advantage, and are thus consistent with the occurrence of adaptive mutations in yeast.

Authors
Steele, DF; Jinks-Robertson, S
MLA Citation
Steele, DF, and Jinks-Robertson, S. "An examination of adaptive reversion in Saccharomyces cerevisiae." Genetics 132.1 (1992): 9-21.
PMID
1398066
Source
scival
Published In
Genetics
Volume
132
Issue
1
Publish Date
1992
Start Page
9
End Page
21

Allelic and ectopic interactions in recombination-defective yeast strains

Ectopic recombination in the yeast Saccharomyces cerevisiae has been investigated by examining the effects of mutations known to alter allelic recombination frequencies. A haploid yeast strain disomic for chromosome III was constructed in which allelic recombination can be monitored using leu2 heteroalleles on chromosome III and ectopic recombination can be monitored using ura3 heteroalleles on chromosomes V and II. This strain contains the spo13-1 mutation which permits haploid strains to successfully complete meiosis and which rescues many recombination-defective mutants from the associated meiotic lethality. Mutations in the genes RAD50, SPO11 and HOP1 were introduced individually into this disomic strain using transformation procedures. Mitotic and meiotic comparisons of each mutant strain with the wild-type parental strain has shown that the mutation in question has comparable effects on ectopic and allelic recombination. Similar results have been obtained using diploid strains constructed by mating MATa and MATα haploid derivatives of each of the disomic strains. These data demonstrate that ectopic and allelic recombination are affected by the same gene products and suggest that the two types of recombination are mechanistically similar. In addition, the comparison of disomic and diploid strains indicates that the presence of a chromosome pairing partner during meiosis does not affect the frequency of ectopic recombination events involving nonhomologous chromosomes.

Authors
Steele, DF; Morris, ME; Jinks-Robertson, S
MLA Citation
Steele, DF, Morris, ME, and Jinks-Robertson, S. "Allelic and ectopic interactions in recombination-defective yeast strains." Genetics 127.1 (1991): 53-60.
PMID
2016046
Source
scival
Published In
Genetics
Volume
127
Issue
1
Publish Date
1991
Start Page
53
End Page
60

Segregation of recombinant chromatids following mitotic crossing over in yeast

It has long been assumed that chromatid segregation following mitotic crossing over in yeast is random, with the recombinant chromatids segregating to opposite poles of the cell (x-segregation) or to the same pole of the cell (z-segregation) with equal frequency. X-segregation events can be readily identified because heterozygous markers distal to the point of the exchange are reduced to homozygosity. Z-segregation events yield daughter cells which are identical phenotypically to nonrecombinant cells and thus can only be identified by the altered linkage relationships of genetic markers on opposite sides of the exchange. We have systematically examined the segregation patterns of chromatids with a spontaneous mitotic exchange in the CEN5-CAN1 interval on chromosome V. We find that the number of x-segregation events is equal to the number of z-segregations, thus demonstrating that chromatid segregation is indeed random. In addition, we have found that at least 5% of the cells selected for a recombination event on chromosome V are trisomic for this chromosome, indicating a strong association between mitotic recombination and chromosome nondisjunction.

Authors
Chua, P; Jinks-Robertson, S
MLA Citation
Chua, P, and Jinks-Robertson, S. "Segregation of recombinant chromatids following mitotic crossing over in yeast." Genetics 129.2 (1991): 359-369.
PMID
1660426
Source
scival
Published In
Genetics
Volume
129
Issue
2
Publish Date
1991
Start Page
359
End Page
369

Nucleotide sequence of the LYS2 gene of Saccharomyces cerevisiae: homology to Bacillus brevis tyrocidine synthetase 1

The Saccharomyces cerevisiae L YS2 gene, which encodes α-aminoadipate reductase, an essential enzyme in the yeast lysine biosynthetic pathway, has been sequenced. A large open reading frame (ORF) has been identified which can specify a 1392-amino acid protein with a deduced Mr of 155 344. A DNA database search using the translated LYS2 ORF as a probe has revealed significant aa sequence homology to the Bacillus brevis enzyme tyrocidine synthetase 1. © 1991.

Authors
Morris, ME; Jinks-Robertson, S
MLA Citation
Morris, ME, and Jinks-Robertson, S. "Nucleotide sequence of the LYS2 gene of Saccharomyces cerevisiae: homology to Bacillus brevis tyrocidine synthetase 1." Gene 98.1 (1991): 141-145.
PMID
2013406
Source
scival
Published In
Gene
Volume
98
Issue
1
Publish Date
1991
Start Page
141
End Page
145
DOI
10.1016/0378-1119(91)90117-T

Recombination in yeast and the recombinant DNA technology.

The development of methods to isolate eukaryotic genes, alter these genes in vitro and reintroduce them into the cell has had a major impact on the study of recombination in the yeast Saccharomyces cerevisiae. In this paper we discuss how recombinant DNA techniques have been employed in the study of recombination in yeast and the results that have been obtained in these studies.

Authors
Petes, TD; Detloff, P; Jinks-Robertson, S; Judd, SR; Kupiec, M; Nag, D; Stapleton, A; Symington, LS; Vincent, A; White, M
MLA Citation
Petes, TD, Detloff, P, Jinks-Robertson, S, Judd, SR, Kupiec, M, Nag, D, Stapleton, A, Symington, LS, Vincent, A, and White, M. "Recombination in yeast and the recombinant DNA technology." Genome 31.2 (1989): 536-540. (Review)
PMID
2698829
Source
pubmed
Published In
Genome / National Research Council Canada = Genome / Conseil national de recherches Canada
Volume
31
Issue
2
Publish Date
1989
Start Page
536
End Page
540

MEIOTIC RECOMBINATION BETWEEN REPEATED GENES ON NONHOMOLOGOUS CHROMOSOMES.

Meiotic recombination events between repeated genes on nonhomologous chromosomes are examined. Initially, meiotic conversion was detected by tetrad dissection. Also, random spore analysis was used to detect such conversions. Conversion-associated reciprocal exchange is also discussed.

Authors
Jinks-Robertson, S; Petes, TD
MLA Citation
Jinks-Robertson, S, and Petes, TD. "MEIOTIC RECOMBINATION BETWEEN REPEATED GENES ON NONHOMOLOGOUS CHROMOSOMES." 3 (1987): 43-52.
Source
scival
Volume
3
Publish Date
1987
Start Page
43
End Page
52

Chromosomal translocations generated by high-frequency meiotic recombination between repeated yeast genes.

We have examined meiotic and mitotic recombination between repeated genes on nonhomologous chromosomes in the yeast Saccharomyces cerevisiae. The results of these experiments can be summarized in three statements. First, gene conversion events between repeats on nonhomologous chromosomes occur frequently in meiosis. The frequency of such conversion events is only 17-fold less than the analogous frequency of conversion between genes at allelic positions on homologous chromosomes. Second, meiotic and mitotic conversion events between repeated genes on nonhomologous chromosomes are associated with reciprocal recombination to the same extent as conversion between allelic sequences. The reciprocal exchanges between the repeated genes result in chromosomal translocations. Finally, recombination between repeated genes on nonhomologous chromosomes occurs much more frequently in meiosis than in mitosis.

Authors
Jinks-Robertson, S; Petes, TD
MLA Citation
Jinks-Robertson, S, and Petes, TD. "Chromosomal translocations generated by high-frequency meiotic recombination between repeated yeast genes." Genetics 114.3 (November 1986): 731-752.
PMID
3539696
Source
pubmed
Published In
Genetics
Volume
114
Issue
3
Publish Date
1986
Start Page
731
End Page
752

High-frequency meiotic gene conversion between repeated genes on nonhomologous chromosomes in yeast.

We have used a genetic system that allows detection of meiotic recombination events between repeated sequences on nonhomologous chromosomes in the yeast Saccharomyces cerevisiae. We have found that recombination between these sequences occurs at a frequency of about 0.5%, and the events observed were nonreciprocal (gene conversions). Surprisingly, the frequency of conversion between the repeated genes on nonhomologous chromosomes observed in this study is similar to that observed between allelic genes. This result is discussed in connection with the role of the synaptonemal complex in meiotic recombination and with the relationship between reciprocal and nonreciprocal recombination.

Authors
Jinks-Robertson, S; Petes, TD
MLA Citation
Jinks-Robertson, S, and Petes, TD. "High-frequency meiotic gene conversion between repeated genes on nonhomologous chromosomes in yeast." Proc Natl Acad Sci U S A 82.10 (May 1985): 3350-3354.
PMID
3889906
Source
pubmed
Published In
Proceedings of the National Academy of Sciences of USA
Volume
82
Issue
10
Publish Date
1985
Start Page
3350
End Page
3354

Expression of rRNA and tRNA genes in Escherichia coli: Evidence for feedback regulation by products of rRNA operons

We have tested a model for global ribosome biosynthesis by examining the effects of increased gene dosage on the synthesis of rRNA. Increasing gene dosage does not lead to a significant increase in total rRNA transcription; i.e., rRNA synthesis from individual rRNA operons is reduced to keep total rRNA production unchanged. In contrast, when the plasmid-encoded rRNA operons used to increase gene dosage contain deletions within the rRNA coding region, rRNA transcription is gene-dosage-dependent; i.e., rRNA regulation is relieved. We find that the syntheses of most, if not all, tRNAs are also subject to the same controls as rRNA transcription. We conclude that the production of functional rRNA is monitored by the regulatory system that controls rRNA and tRNA transcription. We propose that rRNA and tRNA are negatively controlled by products of rRNA operons and discuss evidence suggesting that ribosomes are the key element involved in the postulated feedback regulation. © 1983.

Authors
Jinks-Robertson, S; Gourse, RL; Nomura, M
MLA Citation
Jinks-Robertson, S, Gourse, RL, and Nomura, M. "Expression of rRNA and tRNA genes in Escherichia coli: Evidence for feedback regulation by products of rRNA operons." Cell 33.3 (1983): 865-876.
PMID
6191870
Source
scival
Published In
Cell
Volume
33
Issue
3
Publish Date
1983
Start Page
865
End Page
876

Ribosomal protein S4 acts in trans as a translational repressor to regulate expression of the α operon in Escherichia coli

Authors
Jinks-Robertson, S; Nomura, M
MLA Citation
Jinks-Robertson, S, and Nomura, M. "Ribosomal protein S4 acts in trans as a translational repressor to regulate expression of the α operon in Escherichia coli." Journal of Bacteriology 151.1 (1982): 193-202.
PMID
6211432
Source
scival
Published In
Journal of Bacteriology
Volume
151
Issue
1
Publish Date
1982
Start Page
193
End Page
202

Regulation of ribosomal protein synthesis in an Escherichia coli mutant missing ribosomal protein L1

Authors
Jinks-Robertson, S; Nomura, M
MLA Citation
Jinks-Robertson, S, and Nomura, M. "Regulation of ribosomal protein synthesis in an Escherichia coli mutant missing ribosomal protein L1." Journal of Bacteriology 145.3 (1981): 1445-1447.
PMID
7009590
Source
scival
Published In
Journal of Bacteriology
Volume
145
Issue
3
Publish Date
1981
Start Page
1445
End Page
1447
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