Mrc1 and Srs2 are major actors in the regulation of spontaneous crossover

Robert, Thomas; Dervins, Delphine; Fabre, Francis; Gangloff, Serge

doi:10.1038/sj.emboj.7601158

Cited by 94 publications

(118 citation statements)

References 72 publications

(105 reference statements)

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“…A shared function of Srs2 and Mph1 is preventing crossover events during mitotic recombination (31)(32)(33). However, we found that, unlike mph1⌬, srs2⌬ increased the sensitivity of mms21-11 cells to MMS (Fig.…”

Section: Absence Of Mph1 or Its Helicase Function Suppresses The Accucontrasting

confidence: 50%

Interplay between the Smc5/6 complex and the Mph1 helicase in recombinational repair

Chen

Choi²,

Szakál³

et al. 2009

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

134

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The evolutionarily conserved Smc5/6 complex is implicated in recombinational repair, but its function in this process has been elusive. Here we report that the budding yeast Smc5/6 complex directly binds to the DNA helicase Mph1. Mph1 and its helicase activity define a replication-associated recombination subpathway. We show that this pathway is toxic when the Smc5/6 complex is defective, because mph1⌬ and its helicase mutations suppress multiple defects in mutants of the Smc5/6 complex, including their sensitivity to replication-blocking agents, growth defects, and inefficient chromatid separation, whereas MPH1 overexpression exacerbates some of these defects. We further demonstrate that Mph1 and its helicase activity are largely responsible for the accumulation of potentially deleterious recombination intermediates in mutants of the Smc5/6 complex. We also present evidence that mph1⌬ does not alleviate sensitivity to DNA damage or the accumulation of recombination intermediates in cells lacking Sgs1, which is thought to function together with the Smc5/6 complex. Thus, our results reveal a function of the Smc5/6 complex in the Mph1-dependent recombinational subpathway that is distinct from Sgs1. We suggest that the Smc5/6 complex can counteract/ modulate a pro-recombinogenic function of Mph1 or facilitate the resolution of recombination structures generated by Mph1.

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Section: Absence Of Mph1 or Its Helicase Function Suppresses The Accucontrasting

confidence: 50%

Interplay between the Smc5/6 complex and the Mph1 helicase in recombinational repair

Chen

Choi²,

Szakál³

et al. 2009

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

134

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“…8). On the other hand, the S. cerevisiae Srs2 helicase, which facilitates the SDSA mode of recombinational repair in lieu of the crossover pathway, appears to act early in the DSB repair reaction (Ira et al 2003;Robert et al 2006;Sung and Klein 2006). Purified Srs2 utilizes the free energy from ATP hydrolysis to disrupt the Rad51-ssDNA nucleoprotein filament (Krejci et al 2003;Veaute et al 2003), and Srs2's function in promoting noncrossovers may be related to its ability to remove Rad51 from ssDNA.…”

Section: Discussionmentioning

confidence: 99%

“…Crossover and noncrossover pathways have different genetic requirements in mammalian cells as well (Guillon et al 2005). In yeast mitotic cells, we and others demonstrated that two DNA helicases, Sgs1 and Srs2, suppress crossovers in DSBinduced and spontaneous recombination, but in different ways (Ira et al 2003;Lo et al 2006;Robert et al 2006). Sgs1 was also shown to suppress crossing over in the meiotic cycle, particularly when three or four chromatids are involved in recombination (Jessop et al 2006;Oh et al 2007Oh et al , 2008Jessop and Lichten 2008).…”

mentioning

confidence: 99%

Yeast Mph1 helicase dissociates Rad51-made D-loops: implications for crossover control in mitotic recombination

Prakash¹,

Satory²,

Dray³

et al. 2009

Genes Dev.

231

342

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Eukaryotes possess mechanisms to limit crossing over during mitotic homologous recombination, thus avoiding possible chromosomal rearrangements. We show here that budding yeast Mph1, an ortholog of human FancM helicase, utilizes its helicase activity to suppress spontaneous unequal sister chromatid exchanges and DNA double-strand break-induced chromosome crossovers. Since the efficiency and kinetics of break repair are unaffected, Mph1 appears to channel repair intermediates into a noncrossover pathway. Importantly, Mph1 works independently of two other helicases-Srs2 and Sgs1-that also attenuate crossing over. By chromatin immunoprecipitation, we find targeting of Mph1 to double-strand breaks in cells. Purified Mph1 binds D-loop structures and is particularly adept at unwinding these structures. Importantly, Mph1, but not a helicase-defective variant, dissociates Rad51-made D-loops. Overall, the results from our analyses suggest a new role of Mph1 in promoting the noncrossover repair of DNA double-strand breaks.[Keywords: Genome instability; recombination; DNA helicase; crossing over; Fanconi anemia] Supplemental material is available at http://www.genesdev.org. Received September 8, 2008; revised version accepted November 12, 2008. DNA double-strand breaks (DSBs) that arise during DNA replication or are induced by DNA damaging agents, such as ionizing radiation, are frequently repaired by homologous recombination (HR). In yeast and other eukaryotes, the RAD52 epistasis group of proteins mediate homologous recombination (for reviews, see Paques and Haber 1999;Krogh and Symington 2004). In this process, DSB ends are resected by nucleases to create 39 ssDNA that becomes coated with the recombinase protein Rad51. The Rad51-ssDNA nucleoprotein filament then carries out a search for a homologous donor DNA sequence and promotes strand invasion of the donor molecule to form a D-loop (Sung and Klein 2006). After D-loop formation, there appear to be two alternative pathways that result in DSB repair. One pathway involves the formation of a double Holliday junction (dHJ) that can be resolved by symmetrical strand cleavage into either a crossover or noncrossover gene conversion (Szostak et al. 1983). An alternative mechanism, called synthesis-dependent strand annealing (SDSA), posits formation mostly of noncrossovers, and in most cases does not involve a dHJ intermediate (for review, see Paques and Haber 1999). In support of the SDSA model of gene conversion, we showed recently that both newly synthesized strands are inherited by the broken recipient DNA molecule (Ira et al. 2006). The choice between crossover and noncrossover is tightly regulated in both mitotic and meiotic cells. In meiotic S. cerevisiae cells the correct number of crossovers are required for proper chromosome segregation; the proportion of gene conversion accompanied by crossing over varies between 25% and 50% depending on the locus (Roeder 1995). In mitotic cells, the proportion of crossovers is much lower, ranging between <1% and 7 These authors c...

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“…However, HR can lead to a local loss of heterozygosity (LOH) if the recombining sequences are not identical, and to extensive LOH if repair is associated with a crossover between chromosome homologs. Furthermore, if a repeated sequence at an ectopic site is used as the sequence donor and recombination is associated with crossing over, translocations can occur (2,3). When both ends of the DSB share homology with the donor duplex sequence, HR proceeds by a two-ended mechanism, such as DSB repair or synthesis-dependent strand-annealing (SDSA) (4)(5)(6).…”

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confidence: 99%

Break-induced replication occurs by conservative DNA synthesis

Donnianni

Symington

2013

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

158

174

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Break-induced replication (BIR) refers to recombination-dependent DNA synthesis initiated from one end of a DNA double-strand break and can extend for more than 100 kb. BIR initiates by Rad51-catalyzed strand invasion, but the mechanism for DNA synthesis is not known. Here, we used BrdU incorporation to track DNA synthesis during BIR and found that the newly synthesized strands segregate with the broken chromosome, indicative of a conservative mode of DNA synthesis. Furthermore, we show the frequency of BIR is reduced and product formation is progressively delayed when the donor is placed at an increasing distance from the telomere, consistent with replication by a migrating D-loop from the site of initiation to the telomere.H omologous recombination (HR) is an important mechanism to repair DNA double-strand breaks (DSBs) that occur spontaneously during cell growth or following exposure to DNA damaging agents (1). HR relies on the presence of a homologous duplex to template repair of the broken chromosome and is generally considered to be an error-free mechanism. However, HR can lead to a local loss of heterozygosity (LOH) if the recombining sequences are not identical, and to extensive LOH if repair is associated with a crossover between chromosome homologs. Furthermore, if a repeated sequence at an ectopic site is used as the sequence donor and recombination is associated with crossing over, translocations can occur (2, 3). When both ends of the DSB share homology with the donor duplex sequence, HR proceeds by a two-ended mechanism, such as DSB repair or synthesis-dependent strand-annealing (SDSA) (4-6). However, if coordination of the two ends is not maintained or only one end of the break is available, such as at a critically short telomere, repair can occur by break-induced replication (BIR) (7). In this case, following strand invasion replication occurs to the end of the chromosome to generate a stable repaired product (8,9). This process can cause very long gene conversion tracts and significant LOH, and nonreciprocal translocation if invasion occurs at a dispersed repeated sequence (10).The repair of DSBs by HR requires the 5′-3′ nucleolytic degradation of the DNA ends to form invasive 3′ single-stranded DNA (ssDNA) tails (1). The 3′ ssDNA tail created by end resection is bound by Rad51 to form a nucleoprotein filament that searches for homology and promotes pairing between the ssDNA bound by Rad51 and complementary sequence in the donor duplex forming a D-loop intermediate. The invading 3′ end is then used to prime DNA synthesis templated by the donor sequence. If the invading 3′-tail is displaced by helicases and anneals with the other end of break, repair by SDSA results in noncrossover products. If the second end of the break is captured by the D-loop, a double Holliday junction can be generated after DNA repair synthesis and ligation. Double Holliday junctions can either be dissolved by the Sgs1 helicase and Top3 topoisomerase to form noncrossover products or resolved by endonucleases to generate cr...

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Mrc1 and Srs2 are major actors in the regulation of spontaneous crossover

Cited by 94 publications

References 72 publications

Interplay between the Smc5/6 complex and the Mph1 helicase in recombinational repair

Interplay between the Smc5/6 complex and the Mph1 helicase in recombinational repair

Yeast Mph1 helicase dissociates Rad51-made D-loops: implications for crossover control in mitotic recombination

Break-induced replication occurs by conservative DNA synthesis

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