This Article Full Text Full Text (PDF) All Versions of this Article: biophysj.105.070888v1 91/7/2475    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 Skau, K. I. Articles by Turner, M. S. Search for Related Content PubMed PubMed Citation Articles by Skau, K. I. Articles by Turner, M. S.

A Kinetic Model Describing the Processivity of Myosin-V

Karl I. Skau ^* , Rebecca B. Hoyle ^* and Matthew S. Turner 

^* Department of Mathematics, University of Surrey, Guildford, Surrey, United Kingdom; and Department of Physics, Warwick University, Coventry, United Kingdom

Correspondence: Address reprint requests to Dr. Mathew S. Turner, Tel.: 44-24-7652-2257; E-mail: m.s.turner{at}warwick.ac.uk; or to Dr. Rebecca B. Hoyle, Tel.: 44-1483-682638; E-mail: r.hoyle{at}surrey.ac.uk.

The precise details of how myosin-V coordinates the biochemical reactions and mechanical motions of its two head elements to engineer effective processive molecular motion along actin filaments remain unresolved. We compare a quantitative kinetic model of the myosin-V walk, consisting of five basic states augmented by two further states to allow for futile hydrolysis and detachments, with experimental results for run lengths, velocities, and dwell times and their dependence on bulk nucleotide concentrations and external loads in both directions. The model reveals how myosin-V can use the internal strain in the molecule to synchronize the motion of the head elements. Estimates for the rate constants in the reaction cycle and the internal strain energy are obtained by a computational comparison scheme involving an extensive exploration of the large parameter space. This scheme exploits the fact that we have obtained analytic results for our reaction network, e.g., for the velocity but also the run length, diffusion constant, and fraction of backward steps. The agreement with experiment is often reasonable but some open problems are highlighted, in particular the inability of such a general model to reproduce the reported dependence of run length on ADP concentration. The novel way that our approach explores parameter space means that any confirmed discrepancies should give new insights into the reaction network model.

This article has been cited by other articles:

				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]