This Article Full Text Full Text (PDF) All Versions of this Article: biophysj.104.046763v1 88/6/3792    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Vilfan, A. Search for Related Content PubMed PubMed Citation Articles by Vilfan, A.

Elastic Lever-Arm Model for Myosin V

J. Stefan Institute, Ljubljana, Slovenia

Correspondence: Address reprint requests to Andrej Vilfan, E-mail: andrej.vilfan{at}ijs.si.

We present a mechanochemical model for myosin V, a two-headed processive motor protein. We derive the properties of a dimer from those of an individual head, which we model both with a four-state cycle (detached; attached with ADP.Pi; attached with ADP; and attached without nucleotide) and alternatively with a five-state cycle (where the powerstroke is not tightly coupled to the phosphate release). In each state the lever arm leaves the head at a different, but fixed, angle. The lever arm itself is described as an elastic rod. The chemical cycles of both heads are coordinated exclusively by the mechanical connection between the two lever arms. The model explains head coordination by showing that the lead head only binds to actin after the powerstroke in the trail head and that it only undergoes its powerstroke after the trail head unbinds from actin. Both models (four- and five-state) reproduce the observed hand-over-hand motion and fit the measured force-velocity relations. The main difference between the two models concerns the load dependence of the run length, which is much weaker in the five-state model. We show how systematic processivity measurement under varying conditions could be used to distinguish between both models and to determine the kinetic parameters.

This article has been cited by other articles:

				N. M. Kad, K. M. Trybus, and D. M. Warshaw Load and Pi Control Flux through the Branched Kinetic Cycle of Myosin V J. Biol. Chem., June 20, 2008; 283(25): 17477 - 17484. [Abstract] [Full Text] [PDF]

				A. Vilfan Myosin V Passing over Arp2/3 Junctions: Branching Ratio Calculated from the Elastic Lever Arm Model Biophys. J., May 1, 2008; 94(9): 3405 - 3412. [Abstract] [Full Text] [PDF]

				A. R. Hodges, E. B. Krementsova, and K. M. Trybus She3p Binds to the Rod of Yeast Myosin V and Prevents It from Dimerizing, Forming a Single-headed Motor Complex J. Biol. Chem., March 14, 2008; 283(11): 6906 - 6914. [Abstract] [Full Text] [PDF]

				M. Linden and M. Wallin Dwell Time Symmetry in Random Walks and Molecular Motors Biophys. J., June 1, 2007; 92(11): 3804 - 3816. [Abstract] [Full Text] [PDF]

				G. Lan and S. X. Sun Flexible Light-Chain and Helical Structure of F-Actin Explain the Movement and Step Size of Myosin-VI Biophys. J., December 1, 2006; 91(11): 4002 - 4013. [Abstract] [Full Text] [PDF]

				K. I. Skau, R. B. Hoyle, and M. S. Turner A Kinetic Model Describing the Processivity of Myosin-V Biophys. J., October 1, 2006; 91(7): 2475 - 2489. [Abstract] [Full Text] [PDF]

				A. E.-M. Clemen, M. Vilfan, J. Jaud, J. Zhang, M. Barmann, and M. Rief Force-Dependent Stepping Kinetics of Myosin-V Biophys. J., June 1, 2005; 88(6): 4402 - 4410. [Abstract] [Full Text] [PDF]