Crowding of Molecular Motors Determines Microtubule Depolymerization

Authored by Erwin Frey, Anna Melbinger, Louis Reese

Date Published: 2011

DOI: 10.1016/j.bpj.2011.09.009

Sponsors: German Research Foundation (Deutsche Forschungsgemeinschaft, DFG)

Platforms: No platforms listed

Model Documentation: Other Narrative Mathematical description

Model Code URLs: Model code not found

Abstract

The assembly and disassembly dynamics of microtubules (MTs) is tightly controlled by MT-associated proteins. Here, we investigate how plus-end-directed depolymerases of the kinesin-8 family regulate MT depolymerization dynamics. Using an individual-based model, we reproduce experimental findings. Moreover, crowding is identified as the key regulatory mechanism of depolymerization dynamics. Our analysis reveals two qualitatively distinct regimes. For motor densities above a particular threshold, a macroscopic traffic jam emerges at the plus-end and the MT dynamics become independent of the motor concentration. Below this threshold, microscopic traffic jams at the tip arise that cancel out the effect of the depolymerization kinetics such that the depolymerization speed is solely determined by the motor density. Because this density changes over the MT length, length-dependent regulation is possible. Remarkably, motor cooperativity affects only the end-residence time of depolymerases and not the depolymerization speed.

Tags

Dynamics movement growth Fission yeast Plus-end Chromosome congression Depolymerase activity Mitotic spindle Kinesin-8 Compartments