Different genetic requirements for repair of replication-born double-strand breaks by sister-chromatid recombination and break-induced replication.
Homologous recombination (HR) is the major mechanism used to repair double-strand breaks (DSBs) that result from replication, but a study of repair of DSBs specifically induced during S-phase is lacking. Using an inverted-repeat assay in which a DSB is generated by the encountering of the replication fork with nicks, we can physically detect repair by sister-chromatid recombination (SCR) and intra-chromatid break-induced replication (IC-BIR). As expected, both events depend on Rad52, but, in contrast to previous data, both require Rad59, suggesting a prominent role of Rad59 in repair of replication-born DSBs. In the absence of Rad51, SCR is severely affected while IC-BIR increases, a phenotype that is also observed in the absence of Rad54 but not of its paralog Rdh54/Tid1. These data are consistent with SCR occurring by Rad51-dependent mechanisms assisted by Rad54, and indicate that in the absence of strand exchange-dependent SCR, breaks can be channeled to IC-BIR, which works efficiently in the absence of Rad51. Our study provides molecular evidence for inversions between repeats occurring by BIR followed by single-strand annealing (SSA) in the absence of strand exchange.
Cortés-Ledesma
Felipe
F
Departamento de Genética, Facultad de Biología, Universidad de Sevilla, and Departamento de Biología Molecular, CABIMER, CSIC-Universidad de Sevilla, Av. Américo Vespucio s/n, 41092 SEVILLA, Spain.
Tous
Cristina
C
Aguilera
Andrés
A
D002842:Chromatids / Q000235:genetics*; D053903:DNA Breaks, Double-Stranded; D004265:DNA Helicases; D004260:DNA Repair; D045643:DNA Repair Enzymes; D004261:DNA Replication; D026942:DNA Topoisomerases; D004268:DNA-Binding Proteins / Q000502:physiology; D051135:Rad51 Recombinase / Q000378:metabolism; D011995:Recombination, Genetic; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism / Q000502:physiology; D012854:Sister Chromatid Exchange
D004268:DNA-Binding Proteins; C400213:RAD59 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C495151:RAD51 protein, S cerevisiae; D051135:Rad51 Recombinase; C075468:RAD54 protein, S cerevisiae; D004265:DNA Helicases; D026942:DNA Topoisomerases; C541336:RDH54 protein, S cerevisiae; D045643:DNA Repair Enzymes