Model for bidirectional movement of cytoplasmic dynein

Area of Science:

• Biophysics
• Molecular Motors
• Cellular Mechanics

Background:

• Cytoplasmic dynein is a motor protein that moves directionally along microtubules.
• Dynein movement is processive and step-wise, influenced by ATP binding and load.
• Backward steps occur, increasing with load, especially near stall force.

Purpose of the Study:

• To investigate the bidirectional movement of a single dynein motor head.
• To model the probability of backward steps using non-equilibrium statistical mechanics.
• To understand dynein's behavior under forces exceeding stall force.

Main Methods:

• Stochastic process modeling of dynein motor head movement.
• Implementation of backward step probability based on fluctuation theorems.
• Kinetic Monte Carlo simulations for velocity validation.

Main Results:

• Dynein exhibits negative velocity (backward motion) beyond stall force.
• Backward movement utilizes ATP hydrolysis similarly to forward motion.
• Simulated velocities align with stochastic rate equation model results.

Conclusions:

• Dynein can move backward against significant loads by hydrolyzing ATP.
• The study provides insights into dynein's force-dependent dynamics.
• Non-equilibrium statistical mechanics effectively models dynein's bidirectional movement.