A strong nonequilibrium bound for sorting of cross-linkers on growing biopolymers

Proc Natl Acad Sci U S A. 2021 Sep 21;118(38):e2102881118. doi: 10.1073/pnas.2102881118.

Abstract

Understanding the role of nonequilibrium 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 nonequilibrium 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 cross-linked by two competing types of actin-binding proteins [S. L. Freedman et al., Proc. Natl. Acad. Sci. U.S.A. 116, 16192-16197 (2019)], we construct a minimal model for such a system and show that the dynamics of a growing actin bundle are subject to a set of thermodynamic constraints that relate its nonequilibrium driving, 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.

Keywords: actin bundling and growth; fluctuation–response relations; microscopic nonequilibrium driving; stochastic thermodynamics.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Actin Cytoskeleton / metabolism
  • Actins / metabolism
  • Biopolymers / metabolism*
  • Microfilament Proteins / metabolism
  • Protein Transport / physiology
  • Thermodynamics

Substances

  • Actins
  • Biopolymers
  • Microfilament Proteins