Cell
Volume 134, Issue 6, 19 September 2008, Pages 1030-1041
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Article
Intramolecular Strain Coordinates Kinesin Stepping Behavior along Microtubules

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Summary

Kinesin advances 8 nm along a microtubule per ATP hydrolyzed, but the mechanism responsible for coordinating the enzymatic cycles of kinesin's two identical motor domains remains unresolved. Here, we have tested whether such coordination is mediated by intramolecular tension generated by the “neck linkers,” mechanical elements that span between the motor domains. When tension is reduced by extending the neck linkers with artificial peptides, the coupling between ATP hydrolysis and forward stepping is impaired and motor's velocity decreases as a consequence. However, speed recovers to nearly normal levels when external tension is applied by an optical trap. Remarkably, external load also induces bidirectional stepping of an immotile kinesin that lacks its mechanical element (neck linker) and fuel (ATP). Our results indicate that the kinesin motor domain senses and responds to strain in a manner that facilitates its plus-end-directed stepping and communication between its two motor domains.

CHEMBIO
PROTEINS
CELLBIO

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Present address: Department of Applied Physics, University of Tokyo, 113-8656 Tokyo, Japan