Crowding of molecular motors determines microtubule depolymerization

Area of Science:

• Cell Biology
• Biophysics

Background:

• Microtubule (MT) dynamics are crucial for cellular processes.
• MT-associated proteins regulate MT assembly and disassembly.
• Kinesin-8 family proteins are plus-end-directed depolymerases.

Purpose of the Study:

• Investigate how kinesin-8 depolymerases regulate MT depolymerization dynamics.
• Identify key regulatory mechanisms governing MT depolymerization.

Main Methods:

• Utilized an individual-based model to simulate MT dynamics.
• Reproduced existing experimental findings.
• Analyzed the impact of motor protein density and crowding.

Main Results:

• Crowding emerges as a critical regulator of MT depolymerization.
• Identified two distinct depolymerization regimes based on motor density.
• High motor density leads to macroscopic traffic jams, independent of concentration.
• Low motor density results in microscopic traffic jams, with speed dependent on motor density.
• Length-dependent regulation of MT dynamics is possible.

Conclusions:

• Crowding is a primary mechanism controlling kinesin-8 mediated MT depolymerization.
• MT depolymerization exhibits distinct behaviors under different motor density conditions.
• Motor cooperativity influences depolymerase residence time but not depolymerization speed.