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AKB: Biologische Physik
AKB 14: Molecular Motors
AKB 14.3: Talk
Tuesday, March 28, 2006, 16:45–17:00, ZEU 255
The mitotic kinesin Eg5 is processive and chemical inhibitors can modulate its speed and run length — •Lukas C. Kapitein1, Benjamin H. Kwok2, Jeffrey H. Kim2, Erwin J.G. Peterman1, Tarun M. Kapoor2, and Christoph F. Schmidt1 — 1Dept. Physics, Vrije Universiteit, Amsterdam, NL — 2Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY 10021, USA
Small molecule inhibitors of kinesin-5, a protein essential for eukaryotic mitosis, represent important alternatives to anti-mitotic agents that target tubulin, a protein needed in dividing and non-dividing cells. Kinesin-5 inhibitors, like monastrol, are the only known specific inhibitors for microtubule-based motor proteins, and act through poorly understood allosteric mechanisms distinct from those utilized by ATP-derivatives. Moreover, the microscopic mechanism of kinesin-5 motility is not known. Here we characterize the motile properties of a vertebrate kinesin-5 (Eg5) in the absence and presence of monastrol, using a GFP-fusion protein in single-molecule fluorescence assays. We find that Eg5, against common belief, is a processive motor like conventional kinesin. Unlike conventional kinesin, its motility is discontinuous, switching between pause and run states. Monastrol inhibition prolongs the pause states and decreases Eg5*s speed and run length. Our data on the modulation of Eg5’s mechano-chemical cycle by a cell-permeable inhibitor provide essential input for the inhibitor’s use as a mechanistic probe and for its development as a chemotherapeutic agent.