title: Generating crossovers by resolution of nicked Holliday junctions: a role for Mus81-Eme1 in meiosis.
abstract: The double Holliday junction (dHJ) is generally regarded to be a key intermediate of meiotic recombination, whose resolution is critical for the formation of crossover recombinants. In fission yeast, the Mus81-Eme1 endonuclease has been implicated in resolving dHJs. Consistent with this role, we show that Mus81-Eme1 is required for generating meiotic crossovers. However, purified Mus81-Eme1 prefers to cleave junctions that mimic those formed during the transition from double-strand break to dHJ. Crucially, these junctions are cleaved by Mus81-Eme1 in precisely the right orientation to guarantee the formation of a crossover every time. These data demonstrate how crossovers could arise without forming or resolving dHJs using an enzyme that is widely conserved amongst eukaryotes.
authors.affiliation: Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom.
authors.forename: Fekret
authors.initials: F
authors.lastname: Osman
authors.forename: Julie
authors.initials: J
authors.lastname: Dixon
authors.forename: Claudette L
authors.initials: CL
authors.lastname: Doe
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Whitby
mesh_terms: D003434:Crossing Over, Genetic / Q000235:genetics; D004247:DNA / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004720:Endonucleases / Q000235:genetics / Q000378:metabolism*; D008540:Meiosis / Q000235:genetics*; D009690:Nucleic Acid Conformation; D011995:Recombination, Genetic / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D012568:Schizosaccharomyces / Q000201:enzymology* / Q000235:genetics; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; D004247:DNA; C442837:Eme1 protein, S pombe; D004720:Endonucleases; C411624:MUS81 protein, S cerevisiae