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A Branched Kinetic Scheme Describes the Mechanochemical Coupling of Myosin Va Processivity in Response to Substrate

Zhang, Chong and Yusuf Ali, M and Warshaw, David M and Kad, Neil M (2012) 'A Branched Kinetic Scheme Describes the Mechanochemical Coupling of Myosin Va Processivity in Response to Substrate.' Biophysical Journal, 103 (4). pp. 728-737. ISSN 0006-3495

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Abstract

Myosin Va is a double-headed cargo-carrying molecular motor that moves processively along cellular actin filaments. Long processive runs are achieved through mechanical coordination between the two heads of myosin Va, which keeps their ATPase cycles out of phase, preventing both heads detaching from actin simultaneously. The biochemical kinetics underlying processivity are still uncertain. Here we attempt to define the biochemical pathways populated by myosin Va by examining the velocity, processive run-length, and individual steps of a Qdot-labeled myosin Va in various substrate conditions (i.e., changes in ATP, ADP, and Pi) under zero load in the single-molecule total internal reflection fluorescence microscopy assay. These data were used to globally constrain a branched kinetic scheme that was necessary to fit the dependences of velocity and run-length on substrate conditions. Based on this model, myosin Va can be biased along a given pathway by changes in substrate concentrations. This has uncovered states not normally sampled by the motor, and suggests that every transition involving substrate binding and release may be strain-dependent

Item Type: Article
Subjects: Q Science > Q Science (General)
Q Science > QH Natural history > QH301 Biology
Divisions: Faculty of Science and Health > Biological Sciences, School of
Depositing User: Neil Kad
Date Deposited: 23 Jan 2013 10:55
Last Modified: 23 Jan 2013 10:55
URI: http://repository.essex.ac.uk/id/eprint/5187

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