Abstract
Target of rapamycin complexes (TORCs), which are vital for nutrient utilization, contain a catalytic subunit with the phosphatidyl inositol kinase-related kinase (PIKK) motif. TORC1 is required for cell growth, while the functions of TORC2 are less well understood. We show here that the fission yeast Schizosaccharomyces pombe TORC2 has a cell cycle role through determining the proper timing of Cdc2 Tyr15 dephosphorylation and the cell size under limited glucose, whereas TORC1 restrains mitosis and opposes securin-separase, which are essential for chromosome segregation. These results were obtained using the previously isolated TORC1 mutant tor2-L2048S in the phosphatidyl inositol kinase (PIK) domain and a new TORC2 mutant tor1-L2045D, which harbours a mutation in the same site. While mutated TORC1 and TORC2 displayed diminished kinase activity and FKBP12/Fkh1-dependent rapamycin sensitivity, their phenotypes were nearly opposite in mitosis. Premature mitosis and the G2-M delay occurred in TORC1 and TORC2 mutants, respectively. Surprisingly, separase/cut1-securin/cut2 mutants were rescued by TORC1/tor2-L2048S mutation or rapamycin addition or even Fkh1 deletion, whereas these mutants showed synthetic defect with TORC2/tor1-L2045D. TORC1 and TORC2 coordinate growth, mitosis and cell size control, such as Wee1 and Cdc25 do for the entry into mitosis.
Keywords:
target of rapamycin, rapamycin, Fkh1, Cdc2, separase.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Amino Acid Substitution
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Bridged Bicyclo Compounds, Heterocyclic / pharmacology
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CDC2 Protein Kinase / metabolism
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Cell Cycle
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Cell Cycle Proteins / genetics
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Cell Cycle Proteins / metabolism*
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Cell Division
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Endopeptidases / genetics
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Endopeptidases / metabolism*
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Genes, Fungal
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Mitosis
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Molecular Sequence Data
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Mutation
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Phosphatidylinositol 3-Kinases / chemistry
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Phosphatidylinositol 3-Kinases / genetics
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Phosphatidylinositol 3-Kinases / metabolism*
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Protein Kinases / chemistry
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Protein Kinases / genetics
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Protein Kinases / metabolism*
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Protein Subunits
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Protein Tyrosine Phosphatases / genetics
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Protein Tyrosine Phosphatases / metabolism
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Recombinant Fusion Proteins / chemistry
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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Schizosaccharomyces / cytology
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Schizosaccharomyces / enzymology*
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Schizosaccharomyces / genetics
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Schizosaccharomyces / growth & development
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Schizosaccharomyces pombe Proteins / chemistry
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Schizosaccharomyces pombe Proteins / genetics
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Schizosaccharomyces pombe Proteins / metabolism*
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Securin
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Separase
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Sequence Homology, Amino Acid
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Sirolimus / pharmacology
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Spindle Apparatus / drug effects
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Spindle Apparatus / genetics
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Thiazolidines / pharmacology
Substances
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Bridged Bicyclo Compounds, Heterocyclic
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Cell Cycle Proteins
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Cut1 protein, S pombe
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Cut2 protein, S pombe
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Protein Subunits
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Recombinant Fusion Proteins
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Schizosaccharomyces pombe Proteins
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Securin
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Thiazolidines
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Protein Kinases
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Tor1 protein, S pombe
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tor2 protein, S pombe
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CDC2 Protein Kinase
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cdc2 protein, S pombe
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Clp1 protein, S. pombe
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Protein Tyrosine Phosphatases
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Endopeptidases
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Separase
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latrunculin A
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Sirolimus