title: Mek1 kinase is regulated to suppress double-strand break repair between sister chromatids during budding yeast meiosis.
abstract: Mek1 is a meiosis-specific kinase in budding yeast which promotes recombination between homologous chromosomes by suppressing double-strand break (DSB) repair between sister chromatids. Previous work has shown that in the absence of the meiosis-specific recombinase gene, DMC1, cells arrest in prophase due to unrepaired DSBs and that Mek1 kinase activity is required in this situation to prevent repair of the breaks using sister chromatids. This work demonstrates that Mek1 is activated in response to DSBs by autophosphorylation of two conserved threonines, T327 and T331, in the Mek1 activation loop. Using a version of Mek1 that can be conditionally dimerized during meiosis, Mek1 function was shown to be promoted by dimerization, perhaps as a way of enabling autophosphorylation of the activation loop in trans. A putative HOP1-dependent dimerization domain within the C terminus of Mek1 has been identified. Dimerization alone, however, is insufficient for activation, as DSBs and Mek1 recruitment to the meiosis-specific chromosomal core protein Red1 are also necessary. Phosphorylation of S320 in the activation loop inhibits sister chromatid repair specifically in dmc1Delta-arrested cells. Ectopic dimerization of Mek1 bypasses the requirement for S320 phosphorylation, suggesting this phosphorylation is necessary for maintenance of Mek1 dimers during checkpoint-induced arrest.
authors.affiliation: Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA.
authors.forename: Hengyao
authors.initials: H
authors.lastname: Niu
authors.forename: Xue
authors.initials: X
authors.lastname: Li
authors.forename: Emily
authors.initials: E
authors.lastname: Job
authors.forename: Caroline
authors.initials: C
authors.lastname: Park
authors.forename: Danesh
authors.initials: D
authors.lastname: Moazed
authors.forename: Steven P
authors.initials: SP
authors.lastname: Gygi
authors.forename: Nancy M
authors.initials: NM
authors.lastname: Hollingsworth
mesh_terms: D000595:Amino Acid Sequence; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000378:metabolism*; D002842:Chromatids / Q000378:metabolism*; D017124:Conserved Sequence; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair; D019281:Dimerization; D004789:Enzyme Activation; D048369:MAP Kinase Kinase 1 / Q000737:chemistry / Q000378:metabolism*; D013058:Mass Spectrometry; D008540:Meiosis; D050296:Microbial Viability; D008954:Models, Biological; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes / Q000378:metabolism; D050505:Mutant Proteins / Q000378:metabolism; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D004718:Saccharomycetales / Q000166:cytology / Q000201:enzymology* / Q000235:genetics*; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry / Q000378:metabolism*; D013172:Spores, Fungal / Q000166:cytology; D013489:Suppression, Genetic; D013912:Threonine / Q000378:metabolism; D013997:Time Factors
chemical_list: D018797:Cell Cycle Proteins; D046912:Multiprotein Complexes; D050505:Mutant Proteins; D029702:Schizosaccharomyces pombe Proteins; D013912:Threonine; C119549:Mek1 protein, S pombe; D048369:MAP Kinase Kinase 1