Traffic Dynamic Instability

TL;DR

This paper introduces a model for microtubule dynamics driven by molecular motors, revealing how traffic jams induce stochastic switching between growth and shrinkage, akin to biological microtubule instability.

Contribution

It develops a lattice gas model linking motor traffic to microtubule instability, combining domain wall theory and simulations to explain bistable motor densities and dynamic switching.

Findings

Traffic jams cause stochastic switching between growth and shrinkage.

Bistable motor density correlates with growth and shrinkage phases.

Theoretical predictions align with stochastic simulation results.

Abstract

Here we study a driven lattice gas model for microtubule depolymerizing molecular motors, where traffic jams of motors induce stochastic switching between microtubule growth and shrinkage. We term this phenomenon \enquote{traffic dynamic instability} because it is reminiscent of microtubule dynamic instability [T. Mitchison and M. Kirschner, Nature 312, 237 (1984)]. The intermittent dynamics of growth and shrinking emerges from the interplay between the arrival of motors at the microtubule tip, motor induced depolymerization, and motor detachment from the tip. The switching dynamics correlates with low and high motor density on the lattice. This leads to an effectively bistable particle density in the system. A refined domain wall theory predicts this transient appearance of different phases in the system. The theoretical results are supported by stochastic simulations.