A strong non-equilibrium bound for sorting of crosslinkers on growing biopolymers

TL;DR

This paper develops a minimal model to understand how non-equilibrium forces influence the self-organization and morphology of actin bundles crosslinked by competing proteins, revealing thermodynamic constraints and flux correlations.

Contribution

It introduces a thermodynamic framework linking non-equilibrium driving, bundle morphology, and molecular fluxes in actin cytoskeleton models, highlighting the role of flux correlations.

Findings

Thermodynamic constraints relate non-equilibrium driving to bundle morphology.

Correlations between molecular fluxes are crucial for understanding system behavior.

Microscopy experiments can estimate microscopic driving forces using the proposed model.

Abstract

Understanding the role of non-equilibrium driving in self-organization is crucial for developing a predictive description of biological systems, yet it is impeded by their complexity. The actin cytoskeleton serves as a paradigm for how equilibrium and non-equilibrium forces combine to give rise to self-organization. Motivated by recent experiments that show that actin filament growth rates can tune the morphology of a growing actin bundle crosslinked by two competing types of actin binding proteins, we construct a minimal model for such a system and show that the dynamics are subject to a set of thermodynamic constraints that relate the non-equilibrium driving, bundle morphology, and molecular fluxes. The thermodynamic constraints reveal the importance of correlations between these molecular fluxes, and offer a route to estimating microscopic driving forces from microscopy experiments.