Computer Simulations Reveal Motor Properties generating stable anti-parallel Microtubule interactions

TL;DR

Computer simulations demonstrate that specific motor protein complexes can generate stable anti-parallel microtubule interactions, potentially explaining mechanisms in mitotic spindle formation.

Contribution

This study reveals, through simulations, that hetero-motor complexes of opposite directionality can produce stable anti-parallel microtubule interactions, a novel insight into spindle dynamics.

Findings

Hetero-motor complexes can stabilize anti-parallel microtubule overlaps.

Minus-end motors cause asters to fuse, plus-end motors cause separation.

Mixed motor complexes can maintain stable anti-parallel interactions.

Abstract

An aster of microtubules is a set of flexible polar filaments with dynamic plus-ends, which irradiate from a common location at which the minus ends of the filaments are found. Processive soluble oligomeric motor complexes can bind simultaneously to two microtubules, and thus exert forces between two asters. Using computer simulations, I have explored systematically the possible steady-state regimes reached by two asters under the action of various kinds of oligomeric motors. As expected, motor complexes can induce the asters to fuse, for example when the complexes consist only of minus-end directed motors, or to fully separate, when the motors are plus-end directed. More surprisingly, complexes made of two motors of opposite directionalities can also lead to anti-parallel interactions between overlapping microtubules that are stable and sustained, like those seen in mitotic spindle structures. This suggests that such hetero-complexes could have significant biological role, if they exist in the cell.