Abstract
In fission yeast the onset of mitosis is brought about by Cdc2/Cdc13 kinase, which is inhibited by the Wee1/Mik1 tyrosine kinases and activated by Cdc25 tyrosine phosphatase. This control network integrates many signals, including those that monitor DNA replication, DNA damage and cell size. We report here that a fission yeast MAP kinase pathway links the cell-cycle G2/M control with changes in the extracellular environment that affect cell physiology. Fission yeast spc1- mutants have a G2 delay that is greatly exacerbated by growth in high osmolarity media and nutrient limitation. A lethal interaction of spc1 and cdc25 mutations shows that Spc1 promotes the onset of mitosis. Spc1 is a MAP kinase homologue that is activated by Wis1 kinase in response to osmotic stress and nutrient limitation. Spc1 is inactivated by Pyp1, a phosphatase previously identified as a mitotic inhibitor. Pyp1 dephosphorylates only tyrosine-173 of Spc1, unlike the dual-specificity phosphatases that have been shown to regulate other MAP kinases.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Amino Acid Sequence
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Animals
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Base Sequence
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Calcium-Calmodulin-Dependent Protein Kinases / antagonists & inhibitors
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Calcium-Calmodulin-Dependent Protein Kinases / genetics
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Calcium-Calmodulin-Dependent Protein Kinases / metabolism*
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Cell Cycle / physiology*
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Cell Cycle Proteins
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Cloning, Molecular
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DNA Primers
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Mitogen-Activated Protein Kinases / genetics
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Mitogen-Activated Protein Kinases / metabolism*
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Molecular Sequence Data
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Mutation
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Phosphorylation
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Protein Tyrosine Phosphatases / metabolism
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Schizosaccharomyces / cytology*
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Schizosaccharomyces / enzymology
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Schizosaccharomyces pombe Proteins / genetics
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Schizosaccharomyces pombe Proteins / metabolism*
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Sequence Homology, Amino Acid
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Tyrosine / metabolism
Substances
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Cell Cycle Proteins
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DNA Primers
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Schizosaccharomyces pombe Proteins
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Tyrosine
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Calcium-Calmodulin-Dependent Protein Kinases
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Mitogen-Activated Protein Kinases
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Spc1 protein, S pombe
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sty1 protein, S pombe
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Protein Tyrosine Phosphatases
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pyp1 protein, S pombe
Associated data
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GENBANK/L06279
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GENBANK/L35253
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GENBANK/U26739
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GENBANK/X57334
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GENBANK/X80751