title: Shu1 promotes homolog bias of meiotic recombination in Saccharomyces cerevisiae.
abstract: Homologous recombination occurs closely between homologous chromatids with highly ordered recombinosomes through RecA homologs and mediators. The present study demonstrates this relationship during the period of "partner choice" in yeast meiotic recombination. We have examined the formation of recombination intermediates in the absence or presence of Shu1, a member of the PCSS complex, which also includes Psy3, Csm2, and Shu2. DNA physical analysis indicates that Shu1 is essential for promoting the establishment of homolog bias during meiotic homologous recombination, and the partner choice is switched by Mek1 kinase activity. Furthermore, Shu1 promotes both crossover (CO) and non-crossover (NCO) pathways of meiotic recombination. The inactivation of Mek1 kinase allows for meiotic recombination to progress efficiently, but is lost in homolog bias where most doublestrand breaks (DSBs) are repaired via stable intersister joint molecules. Moreover, the Srs2 helicase deletion cells in the budding yeast show slightly reduced COs and NCOs, and Shu1 promotes homolog bias independent of Srs2. Our findings reveal that Shu1 and Mek1 kinase activity have biochemically distinct roles in partner choice, which in turn enhances the understanding of the mechanism associated with the precondition for homolog bias.
authors.affiliation: Department of Life Sciences, Chung-Ang University, Seoul, 156-756, Korea.
authors.forename: Soogil
authors.initials: S
authors.lastname: Hong
authors.forename: Keun Pil
authors.initials: KP
authors.lastname: Kim
mesh_terms: D015825:Chromosomes, Fungal; D053903:DNA Breaks, Double-Stranded; D004265:DNA Helicases / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D059765:Homologous Recombination; D048369:MAP Kinase Kinase 1 / Q000378:metabolism; D008540:Meiosis / Q000235:genetics* / Q000502:physiology; D009154:Mutation; D009687:Nuclear Proteins / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
chemical_list: C581931:Csm2 protein, S cerevisiae; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; C523513:PSY3 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C562223:Shu1 protein, S cerevisiae; C061376:SRS2 protein, S cerevisiae; D048369:MAP Kinase Kinase 1; D004265:DNA Helicases