title: Fission yeast rad51 and dmc1, two efficient DNA recombinases forming helical nucleoprotein filaments.
abstract: Homologous recombination is important for the repair of double-strand breaks during meiosis. Eukaryotic cells require two homologs of Escherichia coli RecA protein, Rad51 and Dmc1, for meiotic recombination. To date, it is not clear, at the biochemical level, why two homologs of RecA are necessary during meiosis. To gain insight into this, we purified Schizosaccharomyces pombe Rad51 and Dmc1 to homogeneity. Purified Rad51 and Dmc1 form homo-oligomers, bind single-stranded DNA preferentially, and exhibit DNA-stimulated ATPase activity. Both Rad51 and Dmc1 promote the renaturation of complementary single-stranded DNA. Importantly, Rad51 and Dmc1 proteins catalyze ATP-dependent strand exchange reactions with homologous duplex DNA. Electron microscopy reveals that both S. pombe Rad51 and Dmc1 form nucleoprotein filaments. Rad51 formed helical nucleoprotein filaments on single-stranded DNA, whereas Dmc1 was found in two forms, as helical filaments and also as stacked rings. These results demonstrate that Rad51 and Dmc1 are both efficient recombinases in lower eukaryotes and reveal closer functional and structural similarities between the meiotic recombinase Dmc1 and Rad51. The DNA strand exchange activity of both Rad51 and Dmc1 is most likely critical for proper meiotic DNA double-strand break repair in lower eukaryotes.
authors.affiliation: Genome Stability Laboratory, Laval University Cancer Research Center, Hôtel-Dieu de Québec, 9 McMahon, Quebec City, Quebec G1R 2J6, Canada.
authors.forename: Synthia
authors.initials: S
authors.lastname: Sauvageau
authors.forename: Alicja Z
authors.initials: AZ
authors.lastname: Stasiak
authors.forename: Isabelle
authors.initials: I
authors.lastname: Banville
authors.forename: Mickaël
authors.initials: M
authors.lastname: Ploquin
authors.forename: Andrzej
authors.initials: A
authors.lastname: Stasiak
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Masson
mesh_terms: D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D004260:DNA Repair; D004277:DNA, Single-Stranded / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D009698:Nucleoproteins / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D025941:Protein Interaction Mapping; D051135:Rad51 Recombinase; D011938:Rec A Recombinases / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D011995:Recombination, Genetic; D012568:Schizosaccharomyces / Q000201:enzymology* / Q000235:genetics; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D020798:Two-Hybrid System Techniques
chemical_list: D018797:Cell Cycle Proteins; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D009698:Nucleoproteins; C084232:RHP51 protein, S pombe; D029702:Schizosaccharomyces pombe Proteins; D051135:Rad51 Recombinase; D011938:Rec A Recombinases; C074556:DMC1 protein, human