Motor-driven Dynamics of Cytoskeletal FIlaments in Motility Assays

TL;DR

This paper presents an analytical model of cytoskeletal filament dynamics driven by motor proteins, revealing how motor binding/unbinding and load dependence influence filament motion and effective propulsion.

Contribution

It introduces a detailed analytical framework for filament motility incorporating motor binding dynamics and load-dependent transition rates, highlighting non-Markovian effects.

Findings

Filament behaves as a self-propelled rod at long times

Effective propulsion force depends on microscopic motor parameters

Active renormalization of friction and diffusion constants calculated

Abstract

We model analytically the dynamics of a cytoskeletal filament in a motility assay. The filament is described as rigid rod free to slide in two dimensions. The motor proteins consist of polymeric tails tethered to the plane and modeled as linear springs and motor heads that bind to the filament. As in related models of rigid and soft two-state motors, the binding/unbinding dynamics of the motor heads and the dependence of the transition rates on the load exerted by the motor tails play a crucial role in controlling the filament's dynamics. Our work shows that the filament effectively behaves as a self-propelled rod at long times, but with non-Markovian noise sources arising from the coupling to the motor binding/unbinding dynamics. The effective propulsion force of the filament and the active renormalization of the various friction and diffusion constants are calculated in terms of microscopic motor and filament parameters. These quantities could be probed by optical force microscopy.