title: Sgs1 and Mph1 Helicases Enforce the Recombination Execution Checkpoint During DNA Double-Strand Break Repair in Saccharomyces cerevisiae.
abstract: We have previously shown that a recombination execution checkpoint (REC) regulates the choice of the homologous recombination pathway used to repair a given DNA double-strand break (DSB) based on the homology status of the DSB ends. If the two DSB ends are synapsed with closely-positioned and correctly-oriented homologous donors, repair proceeds rapidly by the gene conversion (GC) pathway. If, however, homology to only one of the ends is present, or if homologies to the two ends are situated far away from each other or in the wrong orientation, REC blocks the rapid initiation of new DNA synthesis from the synapsed end(s) and repair is carried out by the break-induced replication (BIR) machinery after a long pause. Here we report that the simultaneous deletion of two 3'→5' helicases, Sgs1 and Mph1, largely abolishes the REC-mediated lag normally observed during the repair of large gaps and BIR substrates, which now get repaired nearly as rapidly and efficiently as GC substrates. Deletion of SGS1 and MPH1 also produces a nearly additive increase in the efficiency of both BIR and long gap repair; this increase is epistatic to that seen upon Rad51 overexpression. However, Rad51 overexpression fails to mimic the acceleration in repair kinetics that is produced by sgs1Δ mph1Δ double deletion.
authors.affiliation: Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts 02454.
authors.forename: Suvi
authors.initials: S
authors.lastname: Jain
authors.affiliation: Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts 02454.
authors.forename: Neal
authors.initials: N
authors.lastname: Sugawara
authors.affiliation: Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts 02454.
authors.forename: Anuja
authors.initials: A
authors.lastname: Mehta
authors.affiliation: Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts 02454.
authors.forename: Taehyun
authors.initials: T
authors.lastname: Ryu
authors.affiliation: Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts 02454 haber@brandeis.edu.
authors.forename: James E
authors.identifier: 0000-0002-1878-0610
authors.initials: JE
authors.lastname: Haber
mesh_terms: D053487:DEAD-box RNA Helicases / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D051135:Rad51 Recombinase / Q000235:genetics / Q000378:metabolism; D053484:RecQ Helicases / Q000235:genetics / Q000378:metabolism*; D059767:Recombinational DNA Repair; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D029701:Saccharomyces cerevisiae Proteins; C495151:RAD51 protein, S cerevisiae; D051135:Rad51 Recombinase; C491240:MPH1 protein, S cerevisiae; C090472:SGS1 protein, S cerevisiae; D053484:RecQ Helicases; D053487:DEAD-box RNA Helicases
keywords: Mph1; Sgs1; break-induced replication (BIR); gene conversion (GC); recombination execution checkpoint (REC)