title: Multiple regulation of Rad51-mediated homologous recombination by fission yeast Fbh1.
abstract: Fbh1, an F-box helicase related to bacterial UvrD, has been proposed to modulate homologous recombination in fission yeast. We provide several lines of evidence for such modulation. Fbh1, but not the related helicases Srs2 and Rqh1, suppressed the formation of crossover recombinants from single HO-induced DNA double-strand breaks. Purified Fbh1 in complex with Skp1 (Fbh1-Skp1 complex) inhibited Rad51-driven DNA strand exchange by disrupting Rad51 nucleoprotein filaments in an ATP-dependent manner; this disruption was alleviated by the Swi5-Sfr1 complex, an auxiliary activator of Rad51. In addition, the reconstituted SCFFbh1 complex, composed of purified Fbh1-Skp1 and Pcu1-Rbx1, displayed ubiquitin-ligase E3 activity toward Rad51. Furthermore, Fbh1 reduced the protein level of Rad51 in stationary phase in an F-box-dependent, but not in a helicase domain-independent manner. These results suggest that Fbh1 negatively regulates Rad51-mediated homologous recombination via its two putative, unrelated activities, namely DNA unwinding/translocation and ubiquitin ligation. In addition to its anti-recombinase activity, we tentatively suggest that Fbh1 might also have a pro-recombination role in vivo, because the Fbh1-Skp1 complex stimulated Rad51-mediated strand exchange in vitro after strand exchange had been initiated.
authors.affiliation: Department of Biological Sciences, School and Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Meguro-ku, Tokyo, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Tsutsui
authors.affiliation: Education Academy of Computational Life Science, Tokyo Institute of Technology, Meguro-ku, Tokyo, Japan.
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Kurokawa
authors.affiliation: Department of Biological Sciences, School and Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Meguro-ku, Tokyo, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Ito
authors.affiliation: Department of Biological Sciences, School and Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Meguro-ku, Tokyo, Japan.
authors.forename: Md Shahjahan P
authors.initials: MS
authors.lastname: Siddique
authors.affiliation: Department of Biological Sciences, School and Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Meguro-ku, Tokyo, Japan.
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Kawano
authors.affiliation: International Institute for Advanced Studies, Kizugawa, Kyoto, Japan.
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Yamao
authors.affiliation: Department of Biological Sciences, School and Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Meguro-ku, Tokyo, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Iwasaki
mesh_terms: D003599:Cytoskeleton / Q000235:genetics; D053903:DNA Breaks, Double-Stranded; D004265:DNA Helicases / Q000235:genetics* / Q000378:metabolism; D059765:Homologous Recombination / Q000235:genetics*; D009154:Mutation; D009698:Nucleoproteins / Q000235:genetics / Q000378:metabolism; D051135:Rad51 Recombinase / Q000096:biosynthesis* / Q000235:genetics; D044843:SKP Cullin F-Box Protein Ligases / Q000235:genetics / Q000378:metabolism; D012568:Schizosaccharomyces / Q000235:genetics*; D029702:Schizosaccharomyces pombe Proteins / Q000096:biosynthesis* / Q000235:genetics* / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000235:genetics
chemical_list: D009698:Nucleoproteins; C084232:RHP51 protein, S pombe; D029702:Schizosaccharomyces pombe Proteins; D044843:SKP Cullin F-Box Protein Ligases; C504781:SKP1 protein, S pombe; D044767:Ubiquitin-Protein Ligases; D051135:Rad51 Recombinase; D004265:DNA Helicases; C504739:Fbh1 protein, S pombe