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Science. 2002 Feb 1;295(5556):844-8.

Distinguishing inchworm and hand-over-hand processive kinesin movement by neck rotation measurements.

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  • 1Biophysics and Structural Biology Program, Biochemistry Department, Brandeis University, Waltham, MA 02454-9110, USA.

Abstract

The motor enzyme kinesin makes hundreds of unidirectional 8-nanometer steps without detaching from or freely sliding along the microtubule on which it moves. We investigated the kinesin stepping mechanism by immobilizing a Drosophila kinesin derivative through the carboxyl-terminal end of the neck coiled-coil domain and measuring orientations of microtubules moved by single enzyme molecules at submicromolar adenosine triphosphate concentrations. The kinesin-mediated microtubule-surface linkage was sufficiently torsionally stiff (>/=2.0 +/- 0.9 x 10(-20) Newton meters per radian2) that stepping by the hypothesized symmetric hand-over-hand mechanism would produce 180 degree rotations of the microtubule relative to the immobilized kinesin neck. In fact, there were no rotations, a finding that is inconsistent with symmetric hand-over-hand movement. An alternative "inchworm" mechanism is consistent with our experimental results.

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PMID:
11823639
[PubMed - indexed for MEDLINE]
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