title: Role of the Saccharomyces cerevisiae Rad51 paralogs in sister chromatid recombination.
abstract: Rad51 requires a number of other proteins, including the Rad51 paralogs, for efficient recombination in vivo. Current evidence suggests that the yeast Rad51 paralogs, Rad55 and Rad57, are important in formation or stabilization of the Rad51 nucleoprotein filament. To gain further insights into the function of the Rad51 paralogs, reporters were designed to measure spontaneous or double-strand break (DSB)-induced sister or nonsister recombination. Spontaneous sister chromatid recombination (SCR) was reduced 6000-fold in the rad57 mutant, significantly more than in the rad51 mutant. Although the DSB-induced recombination defect of rad57 was suppressed by overexpression of Rad51, elevated temperature, or expression of both mating-type alleles, the rad57 defect in spontaneous SCR was not strongly suppressed by these same factors. In addition, the UV sensitivity of the rad57 mutant was not strongly suppressed by MAT heterozygosity, even though Rad51 foci were restored under these conditions. This lack of suppression suggests that Rad55 and Rad57 have different roles in the recombinational repair of stalled replication forks compared with DSB repair. Furthermore, these data suggest that most spontaneous SCR initiates from single-stranded gaps formed at stalled replication forks rather than DSBs.
authors.affiliation: Department of Microbiology, Columbia University Medical Center, New York, New York 10032, USA.
authors.forename: Amy M
authors.initials: AM
authors.lastname: Mozlin
authors.forename: Cindy W
authors.initials: CW
authors.lastname: Fung
authors.forename: Lorraine S
authors.initials: LS
authors.lastname: Symington
mesh_terms: D000251:Adenosine Triphosphatases; D053903:DNA Breaks, Double-Stranded / Q000187:drug effects / Q000528:radiation effects; D053904:DNA Breaks, Single-Stranded / Q000187:drug effects / Q000528:radiation effects; D045643:DNA Repair Enzymes; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004171:Diploidy; D005785:Gene Conversion / Q000187:drug effects / Q000528:radiation effects; D006579:Heterozygote; D000072235:Mating Factor; D008957:Models, Genetic; D009153:Mutagens / Q000494:pharmacology; D009154:Mutation / Q000187:drug effects; D010455:Peptides / Q000378:metabolism; D051135:Rad51 Recombinase / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics* / Q000528:radiation effects; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D012854:Sister Chromatid Exchange / Q000187:drug effects / Q000235:genetics* / Q000528:radiation effects; D013489:Suppression, Genetic / Q000187:drug effects / Q000528:radiation effects; D013696:Temperature; D014466:Ultraviolet Rays
chemical_list: D004268:DNA-Binding Proteins; D009153:Mutagens; D010455:Peptides; C087191:RAD55 protein, S cerevisiae; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D000072235:Mating Factor; D051135:Rad51 Recombinase; D000251:Adenosine Triphosphatases; C071451:RAD57 protein, S cerevisiae; D045643:DNA Repair Enzymes