Mutants defective in Rad1-Rad10-Slx4 exhibit a unique pattern of viability during mating-type switching in Saccharomyces cerevisiae.
Efficient repair of DNA double-strand breaks (DSBs) requires the coordination of checkpoint signaling and enzymatic repair functions. To study these processes during gene conversion at a single chromosomal break, we monitored mating-type switching in Saccharomyces cerevisiae strains defective in the Rad1-Rad10-Slx4 complex. Rad1-Rad10 is a structure-specific endonuclease that removes 3' nonhomologous single-stranded ends that are generated during many recombination events. Slx4 is a known target of the DNA damage response that forms a complex with Rad1-Rad10 and is critical for 3'-end processing during repair of DSBs by single-strand annealing. We found that mutants lacking an intact Rad1-Rad10-Slx4 complex displayed RAD9- and MAD2-dependent cell cycle delays and decreased viability during mating-type switching. In particular, these mutants exhibited a unique pattern of dead and switched daughter cells arising from the same DSB-containing cell. Furthermore, we observed that mutations in post-replicative lesion bypass factors (mms2Delta, mph1Delta) resulted in decreased viability during mating-type switching and conferred shorter cell cycle delays in rad1Delta mutants. We conclude that Rad1-Rad10-Slx4 promotes efficient repair during gene conversion events involving a single 3' nonhomologous tail and propose that the rad1Delta and slx4Delta mutant phenotypes result from inefficient repair of a lesion at the MAT locus that is bypassed by replication-mediated repair.
Lyndaker
Amy M
AM
Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853-2703, USA.
Goldfarb
Tamara
T
Alani
Eric
E
D002453:Cell Cycle; D002470:Cell Survival; D053903:DNA Breaks, Double-Stranded; D004249:DNA Damage; D004260:DNA Repair; D045643:DNA Repair Enzymes; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D004706:Endodeoxyribonucleases / Q000235:genetics* / Q000378:metabolism; D004720:Endonucleases / Q000235:genetics* / Q000378:metabolism; D008957:Models, Genetic; D051718:MutS Homolog 2 Protein / Q000032:analysis / Q000378:metabolism; D009154:Mutation; D010641:Phenotype; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D015719:Single-Strand Specific DNA and RNA Endonucleases
D004268:DNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; D004706:Endodeoxyribonucleases; D004720:Endonucleases; C069266:RAD1 protein, S cerevisiae; C505436:SLX4 protein, S cerevisiae; C064162:RAD10 protein, S cerevisiae; D015719:Single-Strand Specific DNA and RNA Endonucleases; C489751:MSH2 protein, S cerevisiae; D051718:MutS Homolog 2 Protein; D045643:DNA Repair Enzymes