title: Mus81, Rhp51(Rad51), and Rqh1 form an epistatic pathway required for the S-phase DNA damage checkpoint.
abstract: The S-phase DNA damage checkpoint slows the rate of DNA synthesis in response to damage during replication. In the fission yeast Schizosaccharomyces pombe, Cds1, the S-phase-specific checkpoint effector kinase, is required for checkpoint signaling and replication slowing; upon treatment with the alkylating agent methyl methane sulfonate, cds1Delta mutants display a complete checkpoint defect. We have identified proteins downstream of Cds1 required for checkpoint-dependant slowing, including the structure-specific endonuclease Mus81 and the helicase Rqh1, which are implicated in replication fork stability and the negative regulation of recombination. Removing Rhp51, the Rad51 recombinase homologue, suppresses the slowing defect of rqh1Delta mutants, but not that of mus81Delta mutant, defining an epistatic pathway in which mus81 is epistatic to rhp51 and rhp51 is epistatic to rqh1. We propose that restraining recombination is required for the slowing of replication in response to DNA damage.
authors.affiliation: Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Willis
authors.forename: Nicholas
authors.initials: N
authors.lastname: Rhind
mesh_terms: D004249:DNA Damage; D004265:DNA Helicases / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004720:Endonucleases / Q000378:metabolism*; D004789:Enzyme Activation; D004843:Epistasis, Genetic; D005434:Flow Cytometry; D008957:Models, Genetic; D009154:Mutation / Q000235:genetics; D051135:Rad51 Recombinase / Q000378:metabolism*; D011995:Recombination, Genetic / Q000235:genetics; D016196:S Phase; D012568:Schizosaccharomyces / Q000166:cytology / Q000201:enzymology*; D029702:Schizosaccharomyces pombe Proteins / Q000378:metabolism*; D015398:Signal Transduction; D013489:Suppression, Genetic
chemical_list: D004268:DNA-Binding Proteins; C495865:MUS81 protein, S pombe; C084232:RHP51 protein, S pombe; D029702:Schizosaccharomyces pombe Proteins; D051135:Rad51 Recombinase; D004720:Endonucleases; D004265:DNA Helicases; C106462:Rqh1 protein, S pombe