Dynamics of Coupled Myosin V Motors

Myosin V motors are dimeric molecular machines that transport intracellular cargo by walking hand-over-hand along actin filaments, using ATP hydrolysis to generate directed motion. Each step results from a force-dependent lever-arm swing that couples mechanical forces to chemical processes within the motors. While the stepping of individual myosin V dimers in isolation has been extensively studied, in cells, myosin V may also operate in ensembles. The latter may enable robust transport through the complex and stochastic cellular environment. We present computational models of coupled myosin V motors that incorporate both force-dependent and force-independent detachment kinetics. Simulations of two-motor systems illustrate how cooperative transport influences the velocity and run length of the systems. Scaling the model to systems of up to about 50 motors, qualitatively preserves our findings.