Phospho-regulated interaction between kinesin-6 Klp9p and microtubule bundler Ase1p promotes spindle elongation.

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.
Mesh Terms:
Anaphase, CDC2 Protein Kinase, Cell Cycle Proteins, Cyclin B, Kinesin, Microtubule-Associated Proteins, Microtubules, Mitotic Spindle Apparatus, Models, Biological, Molecular Motor Proteins, Phosphorylation, Protein Binding, Protein Isoforms, Protein Tyrosine Phosphatases, Recombinant Fusion Proteins, Schizosaccharomyces, Schizosaccharomyces pombe Proteins
Dev. Cell
Date: Aug. 01, 2009
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