Non-equilibrium microtubule fluctuations in a model cytoskeleton

TL;DR

This study demonstrates that microtubule bending fluctuations in a reconstituted actin cytoskeleton can serve as a direct measure of non-equilibrium stress fluctuations driven by motor proteins, revealing collective motor dynamics.

Contribution

It introduces a novel method to quantify non-equilibrium fluctuations in cytoskeletal networks using microtubule dynamics.

Findings

Myosin motors increase fluctuation amplitude

Fluctuations exhibit step-like force signatures

Motor-driven forces are around 10 pN

Abstract

Biological activity gives rise to non-equilibrium fluctuations in the cytoplasm of cells; however, there are few methods to directly measure these fluctuations. Using a reconstituted actin cytoskeleton, we show that the bending dynamics of embedded microtubules can be used to probe local stress fluctuations. We add myosin motors that drive the network out of equilibrium, resulting in an increased amplitude and modified time-dependence of microtubule bending fluctuations. We show that this behavior results from step-like forces on the order of 10 pN driven by collective motor dynamics.