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.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Activating Transcription Factor 1
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Amino Acid Sequence
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Base Sequence
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Basic-Leucine Zipper Transcription Factors
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Carrier Proteins / genetics
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Cloning, Molecular
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Cyclic AMP Response Element-Binding Protein / genetics*
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Cyclic AMP-Dependent Protein Kinases / genetics
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DNA, Fungal / analysis
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DNA-Binding Proteins / genetics*
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Fungal Proteins / genetics*
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G-Box Binding Factors
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G1 Phase / genetics*
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Gene Expression Regulation, Fungal / genetics*
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Genomic Library
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Intracellular Signaling Peptides and Proteins*
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Mitogen-Activated Protein Kinase Kinases
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Molecular Sequence Data
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Mutagenesis
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Nitrogen
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Phosphoproteins
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Phosphorylation
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Protein Kinases
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Protein Serine-Threonine Kinases / genetics
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Recombinant Fusion Proteins
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Restriction Mapping
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Schizosaccharomyces / genetics*
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Schizosaccharomyces pombe Proteins*
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Sequence Analysis, DNA
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Transcription Factors / genetics*
Substances
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Activating Transcription Factor 1
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Basic-Leucine Zipper Transcription Factors
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Carrier Proteins
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Cyclic AMP Response Element-Binding Protein
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DNA, Fungal
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DNA-Binding Proteins
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Fungal Proteins
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G-Box Binding Factors
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Intracellular Signaling Peptides and Proteins
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Phosphoproteins
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Recombinant Fusion Proteins
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Schizosaccharomyces pombe Proteins
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Transcription Factors
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atf1 protein, S pombe
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protein kinase modulator
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Protein Kinases
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Protein Serine-Threonine Kinases
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Cyclic AMP-Dependent Protein Kinases
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Mitogen-Activated Protein Kinase Kinases
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wis1 protein, S pombe
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Nitrogen