Phosphorylation and maximal activity of Saccharomyces cerevisiae meiosis-specific transcription factor Ndt80 is dependent on Ime2.
The Saccharomyces cerevisiae meiosis-specific transcription factor Ndt80 is responsible for the induction of a class of genes referred to as middle sporulation genes. Among the members of this family are the B-type cyclins and other genes whose products are required for meiotic chromosome division and spore morphogenesis. Inactivation of NDT80 leads to a failure to induce the middle sporulation genes and a subsequent arrest in pachytene. The expression of NDT80 is itself highly regulated. The initial transcription of NDT80 is dependent upon the protein kinase Ime2; once Ndt80 protein accumulates, it activates its own promoter, thus generating an autoactivation loop. In addition to being transcriptionally regulated, Ndt80 protein is posttranslationally regulated. Phosphorylation of Ndt80 occurs coincident with its activation as a transcription factor. If expressed prematurely in meiosis, Ndt80 accumulates initially in an unmodified form that is subsequently modified by phosphorylation. In contrast, Ndt80 expressed in ime2 mutant strains does not become modified and has a reduced ability to activate transcription of its target genes. Ime2 can also phosphorylate Ndt80 in vitro, further supporting a direct role for Ime2 in the phosphorylation of Ndt80. These data indicate that Ime2 plays a novel and previously unexpected role in promoting chromosome dissemination and progress through meiotic development by activating Ndt80.
Sopko
Richelle
R
Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2H7.
Raithatha
Sheetal
S
Stuart
David
D
D021581:Active Transport, Cell Nucleus; D001665:Binding Sites; D018797:Cell Cycle Proteins; D002467:Cell Nucleus / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D047908:Intracellular Signaling Peptides and Proteins; D008540:Meiosis / Q000502:physiology*; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins; D013172:Spores, Fungal / Q000502:physiology; D013379:Substrate Specificity; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation
D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D047908:Intracellular Signaling Peptides and Proteins; C097071:NDT80 protein, S cerevisiae; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D011494:Protein Kinases; C064979:IME2 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases