Model for bidirectional movement of cytoplasmic dynein

TL;DR

This paper presents a stochastic model for dynein's bidirectional movement, incorporating non-equilibrium thermodynamics, revealing backward motion beyond stall force and ATP hydrolysis consistency in both directions.

Contribution

It introduces a novel stochastic process model for dynein's bidirectional movement based on Crook's fluctuation theorem, highlighting backward motion beyond stall force.

Findings

Dynein can move backward beyond stall force.

Backward steps increase as load approaches stall.

ATP hydrolysis occurs similarly in forward and backward movement.

Abstract

Cytoplasmic dynein exhibits a directional processive movement on microtubule filaments and is known to move in steps of varying length based on the number of ATP molecules bound to it and the load that it carries. It is experimentally observed that dynein takes occasional backward steps and the frequency of such backward steps increases as the load approaches the stall force. Using a stochastic process model, we investigate the bidirectional movement of single head of a dynein motor. The probability for backward step is implemented based on Crook's fluctuation theorem of non-equilibrium statistical mechanics. We find that the movement of dynein motor is characterized with negative velocity implying backward motion beyond stall force. We observe that the motor moves backward for super stall forces by hydrolyzing the ATP exactly the same way as it does while moving forward for sub stall forces.