BIOPHYSICAL THEORY AND MODELING |
Flexible Light-chain and Helical Structure of F-actin Explain the Movement and Step Size of Myosin-VI
Ganhui Lan 1 and Sean Sun 2*
1 Johns Hopkins
2 Johns Hopkins University
* To whom correspondence should be addressed. E-mail: ssun{at}jhu.edu.
Submitted on May 30, 2006
Revised on July 26, 2006
Accepted on 29 August 2006
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Abstract |
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Myosin-VI is a dimeric isoform of unconventional myosins. Single molecule experiments indicate that myosin-VI and myosin-V are processive molecular motors, but travel toward opposite ends of filamentous actin. Structural studies show several differences between myosin-V and VI, including a significant difference in the light-chain domain connecting the motor domains. Combining the measured kinetics of myosin-VI with the elasticity of the light-chains, and the helical structure of F-actin, we compare and contrast the motility of myosin-VI with myosin-V. We show that the elastic properties of the light-chain domain control the stepping behavior of these motors. Simple models incorporating the motor elastic energy can quantitatively capture most of the observed data. Implications of our result for other processive motors are discussed.
Key Words:
F-actin, Mechanochemical model, molecular motors, myosin, single molecule experiments
