Role of ATP Hydrolysis in the Antirecombinase Function of Saccharomyces cerevisiae Srs2 Protein

• Published in: The Journal of biological chemistry 2004-05, Vol.279 (22), p.23193-23199
• Main Authors: Krejci, Lumir, Macris, Margaret, Li, Ying, Van Komen, Stephen, Villemain, Jana, Ellenberger, Thomas, Klein, Hannah, Sung, Patrick
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphate - metabolism; DNA - metabolism; DNA Helicases - genetics; DNA Helicases - metabolism; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Hydrolysis; Mutation; Rad52 DNA Repair and Recombination Protein; Recombinases - antagonists & inhibitors; Recombination, Genetic; Saccharomyces cerevisiae; Saccharomyces cerevisiae - enzymology; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - metabolism
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M402586200

Mutants of the Saccharomyces cerevisiae SRS2 gene are hyperrecombinogenic and sensitive to genotoxic agents, and they exhibit a synthetic lethality with mutations that compromise DNA repair or other chromosomal processes. In addition, srs2 mutants fail to adapt or recover from DNA damage checkpoint-imposed G2/M arrest. These phenotypic consequences of ablating SRS2 function are effectively overcome by deleting genes of the RAD52 epistasis group that promote homologous recombination, implicating an untimely recombination as the underlying cause of the srs2 mutant phenotypes. TheSRS2-encodedproteinhasasingle-stranded(ss)DNA-dependent ATPase activity, a DNA helicase activity, and an ability to disassemble the Rad51-ssDNA nucleoprotein filament, which is the key catalytic intermediate in Rad51-mediated recombination reactions. To address the role of ATP hydrolysis in Srs2 protein function, we have constructed two mutant variants that are altered in the Walker type A sequence involved in the binding and hydrolysis of ATP. The srs2 K41A and srs2 K41R mutant proteins are both devoid of ATPase and helicase activities and the ability to displace Rad51 from ssDNA. Accordingly, yeast strains harboring these srs2 mutations are hyperrecombinogenic and sensitive to methylmethane sulfonate, and they become inviable upon introducing either the sgs1Δ or rad54Δ mutation. These results highlight the importance of the ATP hydrolysisfueled DNA motor activity in SRS2 functions.