The requirement for ATP hydrolysis by Saccharomyces cerevisiae Rad51 is bypassed by mating-type heterozygosity or RAD54 in high copy.
Rad51 can promote extensive strand exchange in vitro in the absence of ATP hydrolysis, and the Rad51-K191R mutant protein, which can bind but poorly hydrolyze ATP, also promotes strand exchange. A haploid strain expressing the rad51-K191R allele showed an equivalent sensitivity at low doses of ionizing radiation to rad51-K191A or rad51 null mutants and was defective in spontaneous and double-strand break-induced mitotic recombination. However, the rad51-K191R/rad51-K191R diploid sporulated and the haploid spores showed high viability, indicating no apparent defect in meiotic recombination. The DNA repair defect caused by the rad51-K191R allele was suppressed in diploids and by mating-type heterozygosity in haploids. RAD54 expressed from a high-copy-number plasmid also suppressed the gamma-ray sensitivity of rad51-K191R haploids. The suppression by mating-type heterozygosity of the DNA repair defect conferred by the rad51-K191R allele could occur by elevated expression of factors that act to stabilize, or promote catalysis, by the partially functional Rad51-K191R protein.
Department of Microbiology and Institute of Cancer Research, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA.
Elizabeth A
EA
Morgan
Naseem
N
Shah
Lorraine S
LS
Symington
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000483:Alleles; D015153:Blotting, Western; D002384:Catalysis; D002455:Cell Division; D004249:DNA Damage; D004265:DNA Helicases; D004260:DNA Repair; D045643:DNA Repair Enzymes; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004307:Dose-Response Relationship, Radiation; D005656:Fungal Proteins / Q000378:metabolism*; D005720:Gamma Rays; D005800:Genes, Fungal; D049770:Genes, Mating Type, Fungal; D005838:Genotype; D006238:Haploidy; D006579:Heterozygote; D006868:Hydrolysis; D008540:Meiosis; D008957:Models, Genetic; D010957:Plasmids / Q000378:metabolism; D051135:Rad51 Recombinase; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins
D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; D000255:Adenosine Triphosphate; C495151:RAD51 protein, S cerevisiae; D051135:Rad51 Recombinase; C075468:RAD54 protein, S cerevisiae; D004265:DNA Helicases; D045643:DNA Repair Enzymes