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

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 118; no. 38; pp. 1 - 7
• Main Authors: Qiu, Yuqing, Nguyen, Michael, Hocky, Glen M., Dinner, Aaron R., Vaikuntanathan, Suriyanarayanan
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 21.09.2021
• Subjects: Actin; actin bundling and growth; Actin Cytoskeleton - metabolism; Actins - metabolism; Biopolymers; Biopolymers - metabolism; Crosslinking; Cytoskeleton; fluctuation–response relations; Fluxes; Growth rate; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Microfilament Proteins - metabolism; microscopic nonequilibrium driving; Morphology; Physical Sciences; Protein Transport - physiology; Science & Technology - Other Topics; stochastic thermodynamics; Thermodynamics; actin bundling and growth; stochastic thermodynamics; microscopic nonequilibrium driving; fluctuation–response relations
• ISSN: 0027-8424; 1091-6490; 1091-6490
• DOI: 10.1073/pnas.2102881118

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.