<i>MMS2</i>
            , encoding a ubiquitin-conjugating-enzyme-like protein, is a member of the yeast error-free postreplication repair pathway

Broomfield, Stacey; Chow, Barbara L.; Xiao, Wei

doi:10.1073/pnas.95.10.5678

Cited by 249 publications

(247 citation statements)

References 51 publications

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“…RAD6 has been demonstrated to function in the error-free repair pathway, and utilizes RAD6, RAD18, RAD5, Mms2 and Ubc13 (Ulrich and Jentsch, 2000). All these proteins have been shown to interact at least transiently (Broomfield et al, 1998;Ulrich and Jentsch, 2000;Torres-Ramos et al, 2002). RAD6-RAD18 dimers (Bailly et al, 1997;Xin et al, 2000) in the presence of REV3 or RAD30 have been implicated in error-prone lesion bypass (Roche et al, 1995;McDonald et al, 1997;Cejka et al, 2001).…”

Section: Discussionmentioning

confidence: 99%

RAD6B overexpression confers chemoresistance: RAD6 expression during cell cycle and its redistribution to chromatin during DNA damage-induced response

Lyakhovich

Shekhar

2004

Oncogene

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The HR6A and HR6B genes, homologs of the yeast RAD6 gene, encode ubiquitin conjugating enzymes that are required for postreplication repair (PRR) of DNA and damage-induced mutagenesis. We show here that consistent with its role as a PRR protein, HR6 protein (referred as RAD6) expression is cell cycle regulated, with maximal levels expressed in late S/G2 phases of the cell cycle. Exposure of MCF10A cells to adriamycin (ADR) causes enhancement in the levels of RAD6B mRNA and protein.Inclusion of actinomycin D abolishes both basal and ADR-induced RAD6B transcription indicating that ADRinduced effects on RAD6B transcription result from an increase in transcriptional activity rather than from regulation of RAD6B mRNA stability. The increase in RAD6 protein expression observed in ADR-treated cells is dependent upon transcription and de novo protein synthesis, as addition of actinomycin D and cycloheximide eliminated the induction effects. Using in vivo crosslinking experiments, we demonstrate that only a small proportion of RAD6 is associated with chromatin in untreated MCF10A cells. However, treatment with ADR or cisplatin is accompanied by a significant increase and redistribution of RAD6 to DNA, and RAD6, RAD18, PCNA, phosphohistone H3, as well as p53 proteins are all found in the DNA fractions. These findings suggest that although RAD6 protein is present in the nucleus, its recruitment to the chromatin appears to be modulated by DNA damage. Whereas MCF10A cells engineered to overexpress ectopic RAD6B are significantly more resistant to ADR and cisplatin as compared to empty vector-transfected cells, MCF10A cells stably transfected with antisense RAD6B display hypersensitivity to these damage-inducing drugs. Analysis of PRR capacities in cisplatin-treated MCF10A cells stably transfected with empty vector, RAD6B or antisense RAD6B showed that whereas RAD6B-overexpressing and vector control MCF10A cells possessed the ability to convert newly synthesized DNA to higher molecular weight species, MCF10A cells depleted of RAD6B are PRR-compromised. Although no human diseases have been linked to mutations in the PRR pathway genes, these data suggest that RAD6 may play an essential role in DNA damage tolerance and recovery via modulation of PRR, and that imbalances in the levels of RAD6 could lead to changes in drug sensitivity and damage-induced mutagenesis.

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Section: Discussionmentioning

confidence: 99%

RAD6B overexpression confers chemoresistance: RAD6 expression during cell cycle and its redistribution to chromatin during DNA damage-induced response

Lyakhovich

Shekhar

2004

Oncogene

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“…The rad6Δ and rad18Δ mutations, the founding genes of the PRR pathway, displayed an epistatic relationship to exo1Δ ( Figure 1A) [11], suggesting that EXO1 functioned in PRR for MMS tolerance. As mentioned previously, PRR is composed of at least three genetically distinct sub-pathways: a checkpoint pathway; an errorfree pathway; and an error-prone pathway, defined by the genes RAD9 [9], MMS2 [30] and REV3 [10,31,32], respectively. We found that mms2Δ was epistatic to exo1Δ, but that both rad9Δ and rev3Δ were synergistic with exo1Δ (see Figure 1B-D) by epistasis analysis for MMS sensitivity.…”

Section: Epistasis Analysis Defines a Role For Exo1 In The Mms2 Errormentioning

confidence: 99%

A mutation in EXO1 defines separable roles in DNA mismatch repair and post-replication repair

et al. 2007

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Replication forks stall at DNA lesions or as a result of an unfavorable replicative environment. These fork stalling events have been associated with recombination and gross chromosomal rearrangements. Recombination and fork bypass pathways are the mechanisms accountable for restart of stalled forks. An important lesion bypass mechanism is the highly conserved postreplication repair (PRR) pathway that is composed of error-prone translesion and error-free bypass branches. EXO1 codes for a Rad2p family member nuclease that has been implicated in a multitude of eukaryotic DNA metabolic pathways that include DNA repair, recombination, replication, and telomere integrity. In this report, we show EXO1 functions in the MMS2 error-free branch of the PRR pathway independent of the role of EXO1 in DNA mismatch repair (MMR). Consistent with the idea that EXO1 functions independently in two separate pathways, we defined a domain of Exo1p required for PRR distinct from those required for interaction with MMR proteins. We then generated a point mutant exo1 allele that was defective for the function of Exo1p in MMR due to disrupted interaction with Mlh1p, but still functional for PRR. Lastly, by using a compound exo1 mutant that was defective for interaction with Mlh1p and deficient for nuclease activity, we provide further evidence that Exo1p plays both structural and catalytic roles during MMR.

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“…However, unlike rev3, the mms2 mutant displays a massively increased spontaneous mutation rate and this increase is dependent on REV functions. Furthermore, the mms2 and rev3 mutations are synergistic with respect to DNA damage sensitivity and the double mutant is comparable to that of the rad18 single mutant [52,53]. Based on these analyses, a model was proposed in which the RAD6 pathway is composed of two independent subpathways: one is mediated by TLS that requires REV1, 3 and 7, whereas the other is mediated by error-free PRR that requires MMS2 [52].…”

Section: Ddt In Saccharomyces Cerevisiaementioning

confidence: 99%

“…An error-free branch within the RAD6 pathway had been proposed but not convincingly demonstrated until the identification and functional characterization of MMS2 [52]. The mms2 mutant is moderately sensitive to a broad range of DNA damaging agents, and epistasis analysis places MMS2 within the RAD6 pathway.…”

Section: Ddt In Saccharomyces Cerevisiaementioning

confidence: 99%

“…Based on these analyses, a model was proposed in which the RAD6 pathway is composed of two independent subpathways: one is mediated by TLS that requires REV1, 3 and 7, whereas the other is mediated by error-free PRR that requires MMS2 [52]. MMS2 encodes a protein homologous to Ubc but lacking the active Cys residue [52]. It turns out that Mms2 forms a stable complex with a true Ubc, Ubc13, and that the Mms2-Ubc13 complex specifically catalyzes the formation of Lys63-linked Ub chains [54].…”

Section: Ddt In Saccharomyces Cerevisiaementioning

confidence: 99%

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Eukaryotic DNA damage tolerance and translesion synthesis through covalent modifications of PCNA

Andersen¹,

Xiao³

2007

Cell Res

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185

187

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npg In addition to well-defined DNA repair pathways, all living organisms have evolved mechanisms to avoid cell death caused by replication fork collapse at a site where replication is blocked due to disruptive covalent modifications of DNA. The term DNA damage tolerance (DDT) has been employed loosely to include a collection of mechanisms by which cells survive replication-blocking lesions with or without associated genomic instability. Recent genetic analyses indicate that DDT in eukaryotes, from yeast to human, consists of two parallel pathways with one being error-free and another highly mutagenic. Interestingly, in budding yeast, these two pathways are mediated by sequential modifications of the proliferating cell nuclear antigen (PCNA) by two ubiquitination complexes Rad6-Rad18 and Mms2-Ubc13-Rad5. Damage-induced monoubiquitination of PCNA by Rad6-Rad18 promotes translesion synthesis (TLS) with increased mutagenesis, while subsequent polyubiquitination of PCNA at the same K164 residue by Mms2-Ubc13-Rad5 promotes error-free lesion bypass. Data obtained from recent studies suggest that the above mechanisms are conserved in higher eukaryotes. In particular, mammals contain multiple specialized TLS polymerases. Defects in one of the TLS polymerases have been linked to genomic instability and cancer. DNA damage toleranceIn the presence of spontaneous or carcinogen-induced DNA damage, living cells have to maintain and complete DNA synthesis or risk replication fork collapse. Since the process of DNA licensing is to ensure the genome is duplicated once and only once during each cell cycle, stalled or collapsed replication forks may not be able to restart, which often results in double-strand breaks (DSBs) and causes compromised genome integrity or cell death. In addition to highly conserved DNA repair pathways, all living organisms have evolved schemes to ensure continuation of DNA synthesis in the presence of damage. These schemes were originally termed DNA postreplication repair (PRR) due to observations of transient shortened nascent DNA structures following S phase in response to DNA damage. In bacteria and unicellular yeast, these shortened DNA segments can be measured by an alkaline sedimentation assay [1] or directly observed in electron micrographs [2]. In wild-type cells, these truncated DNA segments were restored to full length following a short recovery time. One typical experiment [1] involved the restoration of the nascent strand following UV exposure in nucleotide excision repair (NER)-deficient cells and was originally assumed to represent a mechanism of DNA repair. However, further investigation revealed that, although the nascent fragments were re-annealed, the original UV-induced pyrimidine dimers, which were responsible for the generation of single-strand gaps, often persisted in the genome [3,4]. It was argued that the replication-blocking lesion was not necessarily corrected, but rather transiently bypassed and carried over to the next generation. Perhaps it is more beneficial for the organi...

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MMS2 , encoding a ubiquitin-conjugating-enzyme-like protein, is a member of the yeast error-free postreplication repair pathway

Cited by 249 publications

References 51 publications

RAD6B overexpression confers chemoresistance: RAD6 expression during cell cycle and its redistribution to chromatin during DNA damage-induced response

RAD6B overexpression confers chemoresistance: RAD6 expression during cell cycle and its redistribution to chromatin during DNA damage-induced response

A mutation in EXO1 defines separable roles in DNA mismatch repair and post-replication repair

Eukaryotic DNA damage tolerance and translesion synthesis through covalent modifications of PCNA

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