Recruitment of Thr 319-phosphorylated Ndd1p to the FHA domain of Fkh2p requires Clb kinase activity: a mechanism for CLB cluster gene activation.
Activation of the CLB gene cluster through the assembly of Mcm1p-Fkh2p complexes at target promoters is essential for mitotic entry and transition through M phase. We show that the activation of this mitotic transcriptional program is dependent on the recruitment of Ndd1p, a coactivator that performs its essential function by acting through Fkh2p. Although an essential gene, NDD1 is dispensable in cells expressing a truncated form of Fkh2p lacking its C terminus. When phosphorylated on T319, Ndd1p is recruited to CLB cluster promoters by association with the forkhead-associated (FHA) domain of Fkh2p. Substitution of T319 for alanine significantly reduces recruitment of Ndd1p, resulting in loss of normal transcriptional regulation, severe impairment of cell growth, and a budding defect reminiscent of cells with a Cdk-Clb kinase deficiency. Finally, we show that phosphorylation of T319 and recruitment of Ndd1p to CLB2 and SWI5 promoters is dependent on Cdc28-Clb kinase activity. These data provide a model describing the activation of G2/M transcription through the phosphorylation of Ndd1p by Cdc28-Clb kinase activity.
Reynolds
David
D
Department of Molecular Biosciences and Center for Molecular Genetics of Development, University of Adelaide, Adelaide, South Australia.
Shi
Bu Jun
BJ
McLean
Cameron
C
Katsis
Frosa
F
Kemp
Bruce
B
Dalton
Stephen
S
D002453:Cell Cycle / Q000502:physiology; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D051858:Forkhead Transcription Factors; D005810:Multigene Family; D009154:Mutation; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000502:physiology
D018797:Cell Cycle Proteins; C464958:Fkh2 protein, S cerevisiae; D051858:Forkhead Transcription Factors; C118820:NDD1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D011494:Protein Kinases