Motor-free contractility of active biopolymer networks

TL;DR

This paper proposes a novel motor-free mechanism for contractility in active biopolymer networks, based on active crosslinker dynamics and polymer asymmetry, explaining recent experimental observations and potential synthetic applications.

Contribution

It introduces a robust motor-free contractility mechanism driven by active crosslinker binding and asymmetric polymer response, expanding understanding beyond motor-dependent models.

Findings

Contractility arises from active crosslinker dynamics breaking detailed balance.

Asymmetric force-extension response of biopolymers contributes to contraction.

The model explains motor-independent contractility observed in cells.

Abstract

Contractility in animal cells is often generated by molecular motors such as myosin, which require polar substrates for their function. Motivated by recent experimental evidence of motor-independent contractility, we propose a robust motor-free mechanism that can generate contraction in biopolymer networks without the need for substrate polarity. We show that contractility is a natural consequence of active binding/unbinding of crosslinkers that breaks the Principle of Detailed Balance, together with the asymmetric force-extension response of semiflexible biopolymers. We calculate the resulting contractile velocity using both a simple coarse-grained model and a more detailed microscopic model for a viscoelastic biopolymer network. Our model may provide an explanation of recent reports of motor-independent contractility in cells. Our results also suggest a mechanism for generating contractile forces in synthetic active materials.