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Molecular motors robustly drive active gels to a critically connected state

Molecular motors robustly drive active gels to a critically connected state Living systems naturally exhibit internal driving: active, molecular processes drive non-equilibrium phenomena such as metabolism or migration. Active gels constitute a fascinating class of internally driven matter, in which molecular motors exert localized stresses inside polymer networks. There is evidence that network crosslinking is required to allow motors to induce macroscopic contraction. Yet a quantitative understanding of how network connectivity enables contraction is lacking. Here we show experimentally that myosin motors contract crosslinked actin polymer networks to clusters with a scale-free size distribution. This critical behaviour occurs over an unexpectedly broad range of crosslink concentrations. To understand this robustness, we developed a quantitative model of contractile networks that takes into account network restructuring: motors reduce connectivity by forcing crosslinks to unbind. Paradoxically, to coordinate global contractions, motor activity should be low. Otherwise, motors drive initially well-connected networks to a critical state where ruptures form across the entire network. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Nature Physics Springer Journals

Molecular motors robustly drive active gels to a critically connected state

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References (73)

Publisher
Springer Journals
Copyright
Copyright © 2013 by Nature Publishing Group
Subject
Physics; Physics, general; Theoretical, Mathematical and Computational Physics; Classical and Continuum Physics; Atomic, Molecular, Optical and Plasma Physics; Condensed Matter Physics; Complex Systems
ISSN
1745-2473
eISSN
1745-2481
DOI
10.1038/nphys2715
Publisher site
See Article on Publisher Site

Abstract

Living systems naturally exhibit internal driving: active, molecular processes drive non-equilibrium phenomena such as metabolism or migration. Active gels constitute a fascinating class of internally driven matter, in which molecular motors exert localized stresses inside polymer networks. There is evidence that network crosslinking is required to allow motors to induce macroscopic contraction. Yet a quantitative understanding of how network connectivity enables contraction is lacking. Here we show experimentally that myosin motors contract crosslinked actin polymer networks to clusters with a scale-free size distribution. This critical behaviour occurs over an unexpectedly broad range of crosslink concentrations. To understand this robustness, we developed a quantitative model of contractile networks that takes into account network restructuring: motors reduce connectivity by forcing crosslinks to unbind. Paradoxically, to coordinate global contractions, motor activity should be low. Otherwise, motors drive initially well-connected networks to a critical state where ruptures form across the entire network.

Journal

Nature Physics – Springer Journals

Published: Aug 11, 2013

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