Catch bond mechanism in Dynein motor driven collective transport

TL;DR

This paper models the catch bonding behavior of dynein motors and explores how it influences cellular cargo transport, revealing that catch bonds can enhance cargo velocity and significantly alter transport dynamics.

Contribution

It introduces a threshold force bond deformation model for dynein catch bonding and analyzes its impact on cargo transport properties, contrasting with kinesin behavior.

Findings

Catch bonding can increase cargo velocity with applied load.

Transport properties are highly sensitive to catch bond strength and stall force.

Predictions are experimentally testable through motor property modifications.

Abstract

Recent experiments have demonstrated that dynein motor exhibits catch bonding behaviour, in which the unbinding rate of a single dynein decreases with increasing force, for a certain range of force. Motivated by these experiments, we propose a model for catch bonding in dynein using a threshold force bond deformation (TFBD) model wherein catch bonding sets in beyond a critical applied load force. We study the effect of catch bonding on unidirectional transport properties of cellular cargo carried by multiple dynein motors within the framework of this model. We find catch bonding can result in dramatic changes in the transport properties, which are in sharp contrast to kinesin driven unidirectional transport, where catch bonding is absent. We predict that, under certain conditions, the average velocity of the cellular cargo can actually increase as applied load is increased. We characterize the transport properties in terms of a velocity profile phase plot in the parameter space of the catch bond strength and the stall force of the motor. This phase plot yields predictions that may be experimentally accessed by suitable modifications of motor transport and binding properties. Our work necessitates a reexamination of existing theories of collective bidirectional transport of cellular cargo where the catch bond effect of dynein described in this paper is expected to play a crucial role.