title: Mus81 cleavage of Holliday junctions: a failsafe for processing meiotic recombination intermediates?
abstract: The Holliday junction (HJ) is a central intermediate of homologous recombination. Its cleavage is critical for the formation of crossover recombinants during meiosis, which in turn helps to establish chiasmata and promote genetic diversity. Enzymes that cleave HJs, called HJ resolvases, have been identified in all domains of life except eukaryotic nuclei. Controversially, the Mus81-Eme1 endonuclease has been proposed to be an example of a eukaryotic nuclear resolvase. However, hitherto little or no HJ cleavage has been detected in recombinant preparations of Mus81-Eme1. Here, we report the purification of active forms of recombinant Schizosaccharomyces pombe Mus81-Eme1 and Saccharomyces cerevisiae Mus81-Mms4, which display robust HJ cleavage in vitro, which, in the case of Mus81-Eme1, is as good as the archetypal HJ resolvase RuvC in single turnover kinetic analysis. We also present genetic evidence that suggests that this activity might be utilised as a back-up to Mus81-Eme1's main activity of cleaving nicked HJs during meiosis in S. pombe.
authors.affiliation: Department of Biochemistry, University of Oxford, South Parks Road, Oxford, UK.
authors.forename: Louise J
authors.initials: LJ
authors.lastname: Gaskell
authors.forename: Fekret
authors.initials: F
authors.lastname: Osman
authors.forename: Robert J C
authors.initials: RJ
authors.lastname: Gilbert
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Whitby
mesh_terms: D001483:Base Sequence; D003434:Crossing Over, Genetic / Q000187:drug effects; D045566:DNA, Cruciform / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism*; D004706:Endodeoxyribonucleases / Q000378:metabolism; D004720:Endonucleases / Q000302:isolation & purification / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000378:metabolism; D045585:Flap Endonucleases; D008274:Magnesium / Q000494:pharmacology; D008540:Meiosis / Q000187:drug effects; D008957:Models, Genetic; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000302:isolation & purification; D011995:Recombination, Genetic / Q000187:drug effects / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000302:isolation & purification / Q000378:metabolism*; D012568:Schizosaccharomyces / Q000187:drug effects / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins / Q000302:isolation & purification / Q000378:metabolism*; D015534:Trans-Activators / Q000302:isolation & purification / Q000378:metabolism; D014461:Ultracentrifugation
chemical_list: D045566:DNA, Cruciform; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C495865:MUS81 protein, S pombe; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; D015534:Trans-Activators; C069806:ruvC protein, E coli; C442837:Eme1 protein, S pombe; D004706:Endodeoxyribonucleases; D004720:Endonucleases; D045585:Flap Endonucleases; C411624:MUS81 protein, S cerevisiae; C112337:MMS4 protein, S cerevisiae; D008274:Magnesium