Stochastic simulations of cargo transport by processive molecular motors

TL;DR

This paper presents a stochastic simulation framework for cargo transport by multiple kinesin motors, revealing how transport length scales exponentially with motor number and how linker mechanics influence motor cooperation.

Contribution

It introduces a novel adhesive motor dynamics algorithm combining Langevin dynamics with kinetic motor rules for more realistic cargo transport modeling.

Findings

Transport length increases exponentially with the number of motors.

Poissonian fluctuations in the number of motors in binding range.

Cooperativity occurs only at high viscosity and attachment times.

Abstract

We use stochastic computer simulations to study the transport of a spherical cargo particle along a microtubule-like track on a planar substrate by several kinesin-like processive motors. Our newly developed adhesive motor dynamics algorithm combines the numerical integration of a Langevin equation for the motion of a sphere with kinetic rules for the molecular motors. The Langevin part includes diffusive motion, the action of the pulling motors, and hydrodynamic interactions between sphere and wall. The kinetic rules for the motors include binding to and unbinding from the filament as well as active motor steps. We find that the simulated mean transport length increases exponentially with the number of bound motors, in good agreement with earlier results. The number of motors in binding range to the motor track fluctuates in time with a Poissonian distribution, both for springs and cables being used as models for the linker mechanics. Cooperativity in the sense of equal load sharing only occurs for high values for viscosity and attachment time.