Abstract
The spindle midzone-composed of antiparallel microtubules, microtubule-associated proteins (MAPs), and motors-is the structure responsible for microtubule organization and sliding during anaphase B. In general, MAPs and motors stabilize the midzone and motors produce sliding. We show that fission yeast kinesin-6 motor klp9p binds to the microtubule antiparallel bundler ase1p at the midzone at anaphase B onset. This interaction depends upon the phosphorylation states of klp9p and ase1p. The cyclin-dependent kinase cdc2p phosphorylates and its antagonist phosphatase clp1p dephosphorylates klp9p and ase1p to control the position and timing of klp9p-ase1p interaction. Failure of klp9p-ase1p binding leads to decreased spindle elongation velocity. The ase1p-mediated recruitment of klp9p to the midzone accelerates pole separation, as suggested by computer simulation. Our findings indicate that a phosphorylation switch controls the spatial-temporal interactions of motors and MAPs for proper anaphase B, and suggest a mechanism whereby a specific motor-MAP conformation enables efficient microtubule sliding.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Anaphase / physiology
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CDC2 Protein Kinase / genetics
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CDC2 Protein Kinase / metabolism
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Cell Cycle Proteins / genetics
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Cell Cycle Proteins / metabolism
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Cyclin B / genetics
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Cyclin B / metabolism
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Kinesins / genetics
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Kinesins / metabolism*
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Microtubule-Associated Proteins / genetics
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Microtubule-Associated Proteins / metabolism*
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Microtubules / metabolism*
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Models, Biological
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Molecular Motor Proteins / genetics
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Molecular Motor Proteins / metabolism*
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Phosphorylation
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Protein Binding
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Protein Isoforms / genetics
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Protein Isoforms / metabolism*
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Protein Tyrosine Phosphatases / genetics
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Protein Tyrosine Phosphatases / metabolism
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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 / metabolism
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Schizosaccharomyces pombe Proteins / genetics
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Schizosaccharomyces pombe Proteins / metabolism*
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Spindle Apparatus / metabolism*
Substances
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Ase1 protein, S pombe
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Cdc13 protein, S pombe
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Cell Cycle Proteins
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Cyclin B
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Microtubule-Associated Proteins
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Molecular Motor Proteins
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Protein Isoforms
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Recombinant Fusion Proteins
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Schizosaccharomyces pombe Proteins
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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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Kinesins