Saccharomyces cerevisiae DNA helicases Mph1, Srs2 and Sgs1 collaborate for the reinitiation of stalled or collapsed replication forks

TL;DRAbstract

The MPH1 gene from Saccharomyces cerevisiae codes for a DNA helicase involved in the error-free bypass of DNA lesions via homologous recombination. Simultaneous deletion of the MPH1 and SRS2 genes, the latter coding also for a DNA-helicase, results in a severe synthetic growth defect in the yeast background CEN.PK2. The mph1 srs2 synthetic defect is rescued by deleting the RAD51, RAD52, RAD55 and RAD57 genes responsible for the formation of the Rad51 nucleoprotein filament, which is mediating the strand invasion process with an homologous DNA duplex. Deletion of MEC1, RAD53, RAD9, RAD17 and RAD24 genes, involved in the DNA damage checkpoint responses, can also rescue the synthetic defect. Moreover, the rad54 deletion is sub-additive to mph1 in terms of spontaneous mutator phenotype.The mph1 srs2 synthetic defect is less severe in other yeast genetic backgrounds where formation of viable mph1 srs2 spores is observed. The sensitivity of viable mph1 srs2 spores to the DNA-damaging agents

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