A force-dependent state controls the coordination of processive myosin V
- †Department of Biochemistry, Stanford University Medical Center, Stanford, CA 94305; and ‡Department of Physiology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104
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Contributed by James A. Spudich, July 28, 2005
Abstract
Myosin V is an efficient processive molecular motor. Recent experiments have shown how the structure and kinetics of myosin V are specialized to produce a highly processive motor capable of taking multiple 36-nm steps on an actin filament track. Here, we examine how two identical heads coordinate their activity to produce efficient hand-over-hand stepping. We have used a modified laser-trap microscope to apply a ≈2-pN forward or backward force on a single-headed myosin V molecule, hypothesized to simulate forces experienced by the rear or lead head, respectively. We found that pulling forward produces only a small change in the kinetics, whereas pulling backward induces a large reduction in the cycling of the head. These results support a model in which the coordination of myosin V stepping is mediated by strain-generated inhibition of the lead head.
Footnotes
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↵ § To whom correspondence should be addressed. E-mail: jspudich{at}stanford.edu.
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Author contributions: T.J.P. and J.A.S. designed research; T.J.P. performed research; T.J.P. and H.L.S. contributed new reagents/analytic tools; T.J.P., H.L.S., and J.A.S. analyzed data; and T.J.P., H.L.S., and J.A.S. wrote the paper.
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See Commentary on page 13719.
- Copyright © 2005, The National Academy of Sciences
