title: Top3-Rmi1 DNA single-strand decatenase is integral to the formation and resolution of meiotic recombination intermediates.
abstract: The topoisomerase III (Top3)-Rmi1 heterodimer, which catalyzes DNA single-strand passage, forms a conserved complex with the Bloom's helicase (BLM, Sgs1 in budding yeast). This complex has been proposed to regulate recombination by disassembling double Holliday junctions in a process called dissolution. Top3-Rmi1 has been suggested to act at the end of this process, resolving hemicatenanes produced by earlier BLM/Sgs1 activity. We show here that, to the contrary, Top3-Rmi1 acts in all meiotic recombination functions previously associated with Sgs1, most notably as an early recombination intermediate chaperone, promoting regulated crossover and noncrossover recombination and preventing aberrant recombination intermediate accumulation. In addition, we show that Top3-Rmi1 has important Sgs1-independent functions that ensure complete recombination intermediate resolution and chromosome segregation. These findings indicate that Top3-Rmi1 activity is important throughout recombination to resolve strand crossings that would otherwise impede progression through both early steps of pathway choice and late steps of intermediate resolution.
authors.affiliation: Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, Bethesda, MD 20892, USA.
authors.forename: Hardeep
authors.initials: H
authors.lastname: Kaur
authors.affiliation: Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, Bethesda, MD 20892, USA.
authors.forename: Arnaud
authors.initials: A
authors.lastname: De Muyt
authors.affiliation: Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, Bethesda, MD 20892, USA. Electronic address: mlichten@helix.nih.gov.
authors.forename: Michael
authors.initials: M
authors.lastname: Lichten
mesh_terms: D020090:Chromosome Segregation; D004264:DNA Topoisomerases, Type I / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D004720:Endonucleases / Q000378:metabolism / Q000502:physiology; D045585:Flap Endonucleases / Q000378:metabolism / Q000502:physiology; D045565:Holliday Junction Resolvases / Q000378:metabolism / Q000502:physiology; D059765:Homologous Recombination / Q000502:physiology*; D008540:Meiosis / Q000235:genetics*; D008957:Models, Genetic; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism / Q000502:physiology*
chemical_list: D004268:DNA-Binding Proteins; C502206:Rmi1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D004720:Endonucleases; D045585:Flap Endonucleases; C411624:MUS81 protein, S cerevisiae; D045565:Holliday Junction Resolvases; C533749:Yen1 protein, S cerevisiae; C112337:MMS4 protein, S cerevisiae; D004264:DNA Topoisomerases, Type I