Effectiveness of beads for tracking small-scale molecular motor dynamics

Steven J. Lade, Erin M. Craig, and Heiner Linke
Phys. Rev. E 84, 021907 – Published 5 August 2011
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Abstract

Investigations into molecular motor dynamics are increasingly focused on small-scale features of the motor’s motion. We define performance measures of a common type of single-molecule motility assay, the bead assay, for its ability to detect such features. Using numerical models, we explore the dependence of assay performance on a number of experimentally controllable parameters, including bead size, optical force, and the method of attaching the bead to the motor. We find that the best parameter choice depends on the objective of the experiments, and give a guide to parameter selection. Comparison of the models against experimental data from a recent bead assay of myosin V exemplifies how our methods can also be used to extract additional information from bead assays, particularly that related to small-scale features. By analyzing the experimental data we find evidence for previously undetected multiple waiting states of the bead-motor complex. Furthermore, from numerical simulations we find that equilibrium bead dynamics display features previously attributed to aborted motor steps, and that bead dynamics alone can produce multiple subphases during a step.

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  • Received 6 April 2011

DOI:https://doi.org/10.1103/PhysRevE.84.021907

©2011 American Physical Society

Authors & Affiliations

Steven J. Lade*

  • Nonlinear Physics Centre, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 0200, Australia

Erin M. Craig

  • Department of Neurobiology, Physiology and Behavior and Department of Mathematics, University of California, Davis, California 95616, USA

Heiner Linke

  • The Nanometer Structure Consortium (nmC@LU) and Division of Solid State Physics, Lund University, S-22100 Lund, Sweden

  • *Current address: Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Str. 38, D-01187 Dresden, Germany.

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Issue

Vol. 84, Iss. 2 — August 2011

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