title: Suppression of the double-strand-break-repair defect of the Saccharomyces cerevisiae rad57 mutant.
abstract: The Rad51 paralogs Rad55 and Rad57 form a heterodimer required to mediate the formation and/or stabilization of the Rad51 filament. To further characterize the function of Rad55-Rad57, we used a combination of rad57 partial suppressors to determine whether the DNA repair and recombination defects of the rad57 mutant could be completely suppressed. The combination of all suppressors, elevated temperature, srs2, rad51-I345T, and mating-type (MAT) heterozygosity resulted in almost complete suppression of the rad57 mutant defect in the recruitment of Rad51 to DNA-damaged sites, as well as survival in response to ionizing radiation and camptothecin. In a physical assay to monitor the kinetics of double-strand-break (DSB)-induced gene conversion, the rad57 mutant defect was effectively suppressed by srs2 and MAT heterozygosity, but these same suppressors failed to suppress the spontaneous recombination defect. Thus the Rad55-Rad57 heterodimer appears to have a unique function in spontaneous recombination that is not essential for DSB repair. Furthermore, we investigated the currently unknown mechanism of rad57 suppression by MAT heterozygosity and found that it is independent of DNL4.
authors.affiliation: Department of Microbiology, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA.
authors.forename: Cindy W
authors.initials: CW
authors.lastname: Fung
authors.forename: Amy M
authors.initials: AM
authors.lastname: Mozlin
authors.forename: Lorraine S
authors.initials: LS
authors.lastname: Symington
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D053903:DNA Breaks, Double-Stranded; D004265:DNA Helicases / Q000235:genetics; D004260:DNA Repair / Q000235:genetics*; D045643:DNA Repair Enzymes / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D015536:Down-Regulation / Q000235:genetics; D005785:Gene Conversion / Q000235:genetics; D049770:Genes, Mating Type, Fungal / Q000502:physiology; D006579:Heterozygote; D008954:Models, Biological; D050505:Mutant Proteins / Q000235:genetics / Q000502:physiology; D030781:Organisms, Genetically Modified; D055503:Protein Multimerization; D011995:Recombination, Genetic / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism / Q000502:physiology
chemical_list: D004268:DNA-Binding Proteins; D050505:Mutant Proteins; C087191:RAD55 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C061376:SRS2 protein, S cerevisiae; D000251:Adenosine Triphosphatases; C071451:RAD57 protein, S cerevisiae; D004265:DNA Helicases; D045643:DNA Repair Enzymes