The involvement of Srs2 in post-replication repair and homologous recombination in fission yeast

Doe, Claudette L.; Whitby, Matthew C.

doi:10.1093/nar/gkh317

Cited by 56 publications

(81 citation statements)

References 53 publications

(75 reference statements)

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“…Therefore, we began our investigation of the meiotic roles of Rqh1 by examining the effect of an rqh1 null mutation (a complete deletion of the rqh1 coding sequence) on meiotic recombination frequency. In addition, we examined the effect of an srs2 null mutation because of the known interaction between Rqh1 (Sgs1) and Srs2 in mitotic growth and the role of both Rqh1 (Sgs1) and Srs2 proteins in promoting mitotic noncrossover vs. crossover events (Gangloff et al 2000;Maftahi et al 2002;Ira et al 2003;Doe and Whitby 2004;Liberi et al 2005;Hope et al 2007;J. Virgin, personal communication).…”

Section: Resultsmentioning

confidence: 99%

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The Fission Yeast BLM Homolog Rqh1 Promotes Meiotic Recombination

2008

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RecQ helicases are found in organisms as diverse as bacteria, fungi, and mammals. These proteins promote genome stability, and mutations affecting human RecQ proteins underlie premature aging and cancer predisposition syndromes, including Bloom syndrome, caused by mutations affecting the BLM protein. In this study we show that mutants lacking the Rqh1 protein of the fission yeast Schizosaccharomyces pombe, a RecQ and BLM homolog, have substantially reduced meiotic recombination, both gene conversions and crossovers. The relative proportion of gene conversions having associated crossovers is unchanged from that in wild type. In rqh1 mutants, meiotic DNA double-strand breaks are formed and disappear with wild-type frequency and kinetics, and spore viability is only moderately reduced. Genetic analyses and the wild-type frequency of both intersister and interhomolog joint molecules argue against these phenotypes being explained by an increase in intersister recombination at the expense of interhomolog recombination. We suggest that Rqh1 extends hybrid DNA and biases the recombination outcome toward crossing over. Our results contrast dramatically with those from the budding yeast ortholog, Sgs1, which has a meiotic antirecombination function that suppresses recombination events involving more than two DNA duplexes. These observations underscore the multiple recombination functions of RecQ homologs and emphasize that even conserved proteins can be adapted to play different roles in different organisms.

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Section: Resultsmentioning

confidence: 99%

“…The function of Srs2 often seems to be closely linked to that of Sgs1 or Rqh1. Both Sgs1 (Rqh1) and Srs2 proteins have an antirecombination function during mitotic growth of budding and fission yeast (Rong et al 1991;Watt et al 1996;Stewart et al 1997;Wang et al 2001;Doe and Whitby 2004;J. Virgin, personal communication).…”

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confidence: 99%

The Fission Yeast BLM Homolog Rqh1 Promotes Meiotic Recombination

2008

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“…However, Mus81 and Rad54 are not obligatory functional partners: Whereas Mus81 Ϫ/Ϫ ES cells are hypersensitive to hydroxyurea, Rad54 Ϫ/Ϫ ES cells are not (38). Also, in S. pombe, Mus81 and Rad54 likely act in parallel but distinct pathways of DNA repair because mus81rad54 double mutant has severely reduced viability (39). However, poor growth and hypersensitivity of S. pombe mus81rad54 double mutants to genotoxic agents is suppressed by loss of upstream proteins, such as Rad51 and Rad55 (40), indicating a link between the function of these 2 proteins and HR.…”

Section: Discussionmentioning

confidence: 99%

Human Rad54 protein stimulates human Mus81–Eme1 endonuclease

Mazina

Mazin

2008

Proc. Natl. Acad. Sci. U.S.A.

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Rad54, a key protein of homologous recombination, physically interacts with a DNA structure-specific endonuclease, Mus81-Eme1. Genetic data indicate that Mus81-Eme1 and Rad54 might function together in the repair of damaged DNA. In vitro, Rad54 promotes branch migration of Holliday junctions, whereas the Mus81-Eme1 complex resolves DNA junctions by endonucleolytic cleavage. Here, we show that human Rad54 stimulates Mus81-Eme1 endonuclease activity on various Holliday junction-like intermediates. This stimulation is the product of specific interactions between the human Rad54 (hRad54) and Mus81 proteins, considering that Saccharomyces cerevisiae Rad54 protein does not stimulate human Mus81-Eme1 endonuclease activity. Stimulation of Mus81-Eme1 cleavage activity depends on formation of specific Rad54 complexes on DNA substrates occurring in the presence of ATP and, to a smaller extent, of other nucleotide cofactors. Thus, our results demonstrate a functional link between the branch migration activity of hRad54 and the structurespecific endonuclease activity of hMus81-Eme1, suggesting that the Rad54 and Mus81-Eme1 proteins may cooperate in the processing of Holliday junction-like intermediates during homologous recombination or DNA repair.branch migration ͉ Holliday junction resolution ͉ homologous recombination H omologous recombination (HR) is responsible for the repair of DNA double-stranded breaks (DSB) and faithful chromosome segregation during meiosis (1). The Holliday junction (HJ) is a central intermediate of HR (2). HJs are thought to form during meiotic recombination, DSB repair, and repair of collapsed replication forks (3, 4). At late stages of HR or DNA repair, HJs, which constitute a physical link between DNA molecules, must be resolved to allow chromosome separation. Enzymes that cleave HJs, called HJ resolvases, are structure-specific endonucleases that introduce coordinated single-strand cuts across the junction (5). Several HJ resolvases from bacteriophages, eubacteria, archaea, eukaryotic viruses, and mitochondria have been identified, isolated, and characterized (5). However, the identity of eukaryotic nuclear HJ resolvases is still elusive.A role for Mus81 in HJ resolution was first proposed in studies on Schizosaccharomyces pombe, where Mus81 was identified as a critical factor for the production of viable spores, survival under conditions that lead to stalling of replication fork progression, and viability in the absence of RecQ helicase, Rqh1 (6). All of the defects in S. pombe mus81 mutants were rescued by expression of RusA, a bacteriophage resolvase that is highly specific for HJs (7). Mus81 protein is widely conserved among eukaryotes, including Saccharomyces cerevisiae (8), S. pombe (6), Arabidopsis thaliana (9), mice (10, 11), and humans (12). Mus81 is related to the XPF family of structure-specific endonucleases, which share a highly conserved motif (V/IERKX 3 D) that constitutes an integral part of the endonuclease catalytic site. Mus81 functions as a heterodimer with a noncatalytic p...

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“…This recombination may be necessary in some cases to complete replication and maintain viability, but a number of studies have suggested that recombination proteins may also target stalled forks and initiate exchanges when there is no need. They may even cause harm by provoking unequal exchanges between repeated sequences (Rothstein et al 2000;Fabre et al 2002;Doe and Whitby 2004;Schmidt and Kolodner 2004). Faithful duplication of the genome may rely therefore not only on the ability to minimize impediments to fork progression and to rescue any forks that have been damaged, but also to limit unnecessary recombination.…”

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confidence: 99%

Rep and PriA helicase activities prevent RecA from provoking unnecessary recombination during replication fork repair

Mahdi¹,

Buckman²,

Harris³

et al. 2006

Genes Dev.

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The rescue of replication forks stalled on the template DNA was investigated using an assay for synthetic lethality that provides a visual readout of cell viability and permits investigation of why certain mutations are lethal when combined. The results presented show that RecA and other recombination proteins are often engaged during replication because RecA is present and provokes recombination rather than because recombination is necessary. This occurs particularly frequently in cells lacking the helicase activities of Rep and PriA. We propose that these two proteins normally limit the loading of RecA on ssDNA regions exposed on the leading strand template of damaged forks, and do so by unwinding the nascent lagging strand, thus facilitating reannealing of the parental strands. Gap closure followed by loading of the DnaB replicative helicase enables synthesis of the leading strand to continue. Without either activity, RecA loads more frequently on the DNA and drives fork reversal, which creates a chickenfoot structure and a requirement for other recombination proteins to re-establish a viable fork. The assay also reveals that stalled transcription complexes are common impediments to fork progression, and that damaged forks often reverse independently of RecA.[Keywords: DNA repair; RuvABC; RecBCD, RecFOR; Holliday junction] Supplemental material is available at http://www.genesdev.org.

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The involvement of Srs2 in post-replication repair and homologous recombination in fission yeast

Cited by 56 publications

References 53 publications

The Fission Yeast BLM Homolog Rqh1 Promotes Meiotic Recombination

The Fission Yeast BLM Homolog Rqh1 Promotes Meiotic Recombination

Human Rad54 protein stimulates human Mus81–Eme1 endonuclease

Rep and PriA helicase activities prevent RecA from provoking unnecessary recombination during replication fork repair

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