A new cooperation mechanism of kinesin motors when extracting membrane tube

TL;DR

This paper introduces a novel two-track-dumbbell model for kinesin cooperation in membrane tube extraction, considering elasticity and volume exclusion, revealing that 8-9 motors can generate sufficient force for membrane pulling.

Contribution

It proposes a new kinesin cooperation mechanism incorporating elasticity and volume exclusion effects, differing from previous models, and provides simulation results on membrane tube extraction.

Findings

Motors along a single protofilament can extract membrane tubes.

Average number of motors involved is about 8-9.

Results differ significantly from previous studies.

Abstract

Membrane tubes are important elements for living cells to organize many functions. Experiments have found that membrane tube can be extracted from giant lipid vesicles by a group of kinesin. How these motors cooperate in extracting the fluid-like membrane tube is still unclear. In this paper, we propose a new cooperation mechanism called two-track-dumbbell model, in which kinesin is regarded as a dumbbell with an end (tail domain) tightly bound onto the fluid-like membrane and the other end (head domain) stepping on or unbinding from the microtubule. Taking account of the elasticity of kinesin molecule and the exclude volume effect of both the head domain and the tail domain of kinesin, which are not considered in previous models, we simulate the growth process of the membrane tube pulled by kinesin motors. Our results indicate that motors along a single microtubule protofilament can generate enough force to extract membrane tubes from vesicles, and the average number of motors pulling the tube is about 8~9. These results are quite different from previous studies (Ref. \cite{camp.08}), and further experimental tests are necessary to elucidate the cooperation mechanism.