Fkh2p and Sep1p regulate mitotic gene transcription in fission yeast.
In the fission yeast Schizosaccharomyces pombe, several genes including cdc15+, spo12+, fin1+, slp1+, ace2+ and plo1+ are periodically expressed during M phase. The products of these genes control various aspects of cell cycle progression including sister chromatid separation, septation and cytokinesis. We demonstrate that periodic expression of these genes is regulated by a common promoter sequence element, named a PCB. In a genetic screen for cell cycle regulators we have identified a novel forkhead transcription factor, Fkh2p, which is periodically phosphorylated in M phase. We show that Fhk2p and another forkhead transcription factor, Sep1p, are necessary for PCB-driven M-phase-specific transcription. In a previous report we identified a complex by electrophoretic mobility shift assay, which we termed PBF, that binds to a 150 bp region of the cdc15+ promoter that contains the PCB element. We have identified Mbx1p, a novel MADS box protein, as a component of PBF. However, although Mbx1p is periodically phosphorylated in M phase, Mbx1p is not required for periodic gene transcription in M phase. Moreover, although PBF is absent in strains bearing a C-terminal epitope tag on Fkh2p, simultaneous deletion of fkh2+ and sep1+ does not abolish PBF binding activity. This suggests that Mbx1p binds to gene promoters, but is not required for transcriptional activation. Together these results suggest that the activation of the Fkh2p and Sep1p forkhead transcription factors triggers mitotic gene transcription in fission yeast.
Buck
Vicky
V
Division of Yeast Genetics, National Institute for Medical Research, The Ridgeway, Mill Hill, London, NW7 1AA, UK.
Ng
Szu Shien
SS
Ruiz-Garcia
Ana Belen
AB
Papadopoulou
Kyriaki
K
Bhatti
Saeeda
S
Samuel
Jane M
JM
Anderson
Mark
M
Millar
Jonathan B A
JB
McInerny
Christopher J
CJ
D018797:Cell Cycle Proteins / Q000235:genetics; D002455:Cell Division / Q000502:physiology; D005095:Exoribonucleases / Q000235:genetics; D051858:Forkhead Transcription Factors; D016195:G2 Phase / Q000502:physiology; D015966:Gene Expression Regulation, Fungal / Q000502:physiology; D005809:Genes, Regulator / Q000235:genetics; D008938:Mitosis / Q000502:physiology*; D010766:Phosphorylation; D011401:Promoter Regions, Genetic / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D012568:Schizosaccharomyces / Q000166:cytology / Q000235:genetics* / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics* / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation / Q000502:physiology
D018797:Cell Cycle Proteins; C464958:Fkh2 protein, S cerevisiae; D051858:Forkhead Transcription Factors; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; D014157:Transcription Factors; D005095:Exoribonucleases; C068398:XRN1 protein, S cerevisiae