Mek1 kinase activity functions downstream of RED1 in the regulation of meiotic double strand break repair in budding yeast.
Three meiosis-specific chromosomal components in budding yeast, Mek1, Red1, and Hop1, are required for recombination, proper segregation of homologs, and the meiotic recombination checkpoint. Mek1 is a protein kinase. Mutations that increase the size of the ATP binding pocket of Mek1 (mek1-as1) sensitize the kinase to specific small molecule inhibitors. Experiments using mek1-as1 demonstrate that the requirement for Mek1 kinase activity coincides with the formation of double strand breaks (DSBs) and that this activity is necessary after DSB formation to prevent repair by DMC1-independent pathways. Contrary to previous reports, Red1 is not a substrate for Mek1. Instead, RED1 is required for wild-type levels of Mek1 kinase activity. In addition, activation of Mek1 requires HOP1, the formation of Red1/Hop1 complexes and a functional Mek1 FHA domain. The requirement for RED1 to produce active kinase can be bypassed by a mek1 mutation that creates a constitutively active Mek1 kinase. We propose that Red1 is phosphorylated by a kinase other than MEK1 and that phosphothreonines on Red1 then interact with the Mek1 FHA domain to recruit the kinase to sites of DSBs where Mek1 is activated to prevent DMC1-independent DSB repair.
Institute for Cell and Developmental Biology, Department of Biochemistry and Cell Biology, SUNY Stony Brook, Stony Brook, New York 11794-5215, USA.
Lihong
L
Wan
Teresa
T
de los Santos
Chao
C
Zhang
Kevan
K
Shokat
Nancy M
NM
Hollingsworth
D000255:Adenosine Triphosphate / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D004249:DNA Damage / Q000502:physiology; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004789:Enzyme Activation / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D048369:MAP Kinase Kinase 1; D008540:Meiosis / Q000235:genetics / Q000502:physiology*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D009154:Mutation; D010766:Phosphorylation; D011485:Protein Binding; D017434:Protein Structure, Tertiary / Q000502:physiology; D011995:Recombination, Genetic / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins
D018797:Cell Cycle Proteins; C513033:DMC1 protein, S cerevisiae; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; C086672:HOP1 protein, S cerevisiae; C086673:RED1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; D000255:Adenosine Triphosphate; C119549:Mek1 protein, S pombe; D048369:MAP Kinase Kinase 1; D020929:Mitogen-Activated Protein Kinase Kinases