title: Schizosaccharomyces pombe gad7+ encodes a phosphoprotein with a bZIP domain, which is required for proper G1 arrest and gene expression under nitrogen starvation.
abstract: BACKGROUND
  Fission yeast cells arrest at G1 phase when starved of nitrogen. The molecular mechanism that ensures this arrest is poorly understood. We took a genetic approach to this problem.
  
  
  RESULTS
  The fission yeast gad7-1 mutant failed to arrest at G1 when starved of nitrogen, and was poor in mating and sporulation. The gad7 gene was cloned by complementation. The deduced gad7 gene product was a bZIP protein of 566 amino acids, which could bind to the CRE (cAMP response element) sequence in vitro. Disruption of gad7 resulted in the same phenotypes as gad7-1. Expression of ste11, which encodes a key transcription factor for sexual development, was not inducible in the disruptant. Gad7 was co-immunoprecipitated with another bZIP protein Pcr1, suggesting that the two proteins form a heterodimer in vivo. Gad7 was phosphorylated, and the state of its phosphorylation appeared to be modified in pka1delta or wis1delta cells.
  
  
  CONCLUSIONS
  Gad7, a CRE-binding protein that cooperates with Pcr1, is required for proper G1 arrest and gene expression under nitrogen starvation. Gad7 is a phosphoprotein, whose activity may be regulated by protein kinases including the cAMP-dependent protein kinase (Pka1) and Wis1 osmosensory MAP kinase kinase.
authors.affiliation: Department of Biophysics and Biochemistry, School of Science, University of Tokyo, Hongo, Japan.
authors.forename: J
authors.initials: J
authors.lastname: Kanoh
authors.forename: Y
authors.initials: Y
authors.lastname: Watanabe
authors.forename: M
authors.initials: M
authors.lastname: Ohsugi
authors.forename: Y
authors.initials: Y
authors.lastname: Iino
authors.forename: M
authors.initials: M
authors.lastname: Yamamoto
mesh_terms: D051697:Activating Transcription Factor 1; D000595:Amino Acid Sequence; D001483:Base Sequence; D050976:Basic-Leucine Zipper Transcription Factors; D002352:Carrier Proteins / Q000235:genetics; D003001:Cloning, Molecular; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics; D004271:DNA, Fungal / Q000032:analysis; D004268:DNA-Binding Proteins / Q000235:genetics*; D005656:Fungal Proteins / Q000235:genetics*; D051790:G-Box Binding Factors; D016193:G1 Phase / Q000235:genetics*; D015966:Gene Expression Regulation, Fungal / Q000235:genetics*; D015698:Genomic Library; D047908:Intracellular Signaling Peptides and Proteins; D020929:Mitogen-Activated Protein Kinase Kinases; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009584:Nitrogen; D010750:Phosphoproteins; D010766:Phosphorylation; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases / Q000235:genetics; D011993:Recombinant Fusion Proteins; D015183:Restriction Mapping; D012568:Schizosaccharomyces / Q000235:genetics*; D029702:Schizosaccharomyces pombe Proteins; D017422:Sequence Analysis, DNA; D014157:Transcription Factors / Q000235:genetics*
chemical_list: D051697:Activating Transcription Factor 1; D050976:Basic-Leucine Zipper Transcription Factors; D002352:Carrier Proteins; D017362:Cyclic AMP Response Element-Binding Protein; D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D051790:G-Box Binding Factors; D047908:Intracellular Signaling Peptides and Proteins; D010750:Phosphoproteins; D011993:Recombinant Fusion Proteins; D029702:Schizosaccharomyces pombe Proteins; D014157:Transcription Factors; C106740:atf1 protein, S pombe; C015482:protein kinase modulator; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D017868:Cyclic AMP-Dependent Protein Kinases; D020929:Mitogen-Activated Protein Kinase Kinases; C072068:wis1 protein, S pombe; D009584:Nitrogen