Fission yeast Mus81.Eme1 Holliday junction resolvase is required for meiotic crossing over but not for gene conversion.
Most models of homologous recombination invoke cleavage of Holliday junctions to explain crossing over. The Mus81.Eme1 endonuclease from fission yeast and humans cleaves Holliday junctions and other branched DNA structures, leaving its physiological substrate uncertain. We report here that Schizosaccharomyces pombe mus81 mutants have normal or elevated frequencies of gene conversion but 20- to 100-fold reduced frequencies of crossing over. Thus, gene conversion and crossing over can be genetically separated, and Mus81 is required for crossing over, supporting the hypothesis that the fission yeast Mus81.Eme1 protein complex resolves Holliday junctions in meiotic cells.
Smith
Gerald R
GR
Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA. gsmith@fhcrc.org
Boddy
Michael N
MN
Shanahan
Paul
P
Russell
Paul
P
D003434:Crossing Over, Genetic; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000502:physiology*; D004720:Endonucleases / Q000502:physiology*; D005785:Gene Conversion; D008540:Meiosis / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins; D012568:Schizosaccharomyces / Q000201:enzymology / Q000235:genetics* / Q000528:radiation effects; D029702:Schizosaccharomyces pombe Proteins / Q000502:physiology*
D004268:DNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; C442837:Eme1 protein, S pombe; D004720:Endonucleases; C411624:MUS81 protein, S cerevisiae