Elastically coupled molecular motors

TL;DR

This paper investigates how filament elasticity affects the collective force and velocity of molecular motors, revealing a transition from hyperbolic to linear force-velocity relations as backbone flexibility increases.

Contribution

It introduces a model incorporating filament elasticity and strain-dependent detachment, providing new insights into motor dynamics and force generation.

Findings

Force production decreases with increased backbone flexibility.

Maximum velocity remains unchanged despite elasticity.

A crossover from hyperbolic to linear force-velocity relation is observed.

Abstract

We study the influence of filament elasticity on the motion of collective molecular motors. It is found that for a backbone flexibility exceeding a characteristic value (motor stiffness divided through the mean displacement between attached motors), the ability of motors to produce force reduces as compared to rigidly coupled motors, while the maximum velocity remains unchanged. The force-velocity-relation in two different analytic approximations is calculated and compared with Monte-Carlo simulations. Finally, we extend our model by introducing motors with a strain-dependent detachment rate. A remarkable crossover from the nearly hyperbolic shape of the Hill curve for stiff backbones to a linear force-velocity relation for very elastic backbones is found. With realistic model parameters we show that the backbone flexibility plays no role under physiological conditions in muscles, but it should be observable in certain in vitro assays.