The induction of middle meiotic promoters is a key regulatory event in the life cycle of Saccharomyces cerevisiae that controls exit from prophase, meiosis, and spore formation. The Sum1 repressor and Ndt80 activator proteins control middle promoters by binding to overlapping DNA elements. NDT80 is controlled by a tightly regulated middle meiotic promoter through a positive autoregulatory loop and repressed in vegetative cells by Sum1. It has previously been shown that the meiosis-specific kinase, Ime2, promotes the removal of Sum1 from DNA. Here we show that Sum1 is also regulated by the cyclin-dependent kinase, Cdk1. While sum1 phosphosite mutants that are insensitive to Cdk1 or Ime2 complete meiosis and forms spores, a mutant that is insensitive to both Ime2 and Cdk1 (sum1-ci) blocks meiotic development in prophase with an ndt80Delta-like phenotype. Ectopic expression of NDT80 or mutation of a Sum1-binding element in the NDT80 promoter bypasses the sum1-ci block. Hst1 is a NAD(+)-dependent histone deacteylase that is linked to Sum1 by the Rfm1 tethering factor. Deletion of HST1 or RFM1 also bypasses the sum1-ci block. These results demonstrate that Sum1 functions as a key meiotic brake through the NDT80 promoter and that Cdk1 and Ime2 trigger exit from meiotic prophase by inhibiting the Sum1 transcriptional repression complex.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Reference||Annotation Extension|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Conditions||Strain||Source||Reference|