Assembly kinetics determine the architectureof alpha-actinin crosslinked F-actin networks

摘要

The actin cytoskeleton is organized into diverse meshworks and bundles that support manyaspects of cell physiology. understanding the self-assembly of these actin-based structuresis essential for developing predictive models of cytoskeletal organization. Here we showthat the competing kinetics of bundle formation with the onset of dynamic arrest arisingfrom filament entanglements and crosslinking determine the architecture of reconstitutedactin networks formed with alpha-actinin crosslinks. Crosslink-mediated bundle formation onlyoccurs in dilute solutions of highly mobile actin filaments. As actin polymerization proceeds,filament mobility and bundle formation are arrested concomitantly. By controlling the onset ofdynamic arrest, perturbations to actin assembly kinetics dramatically alter the architecture ofbiochemically identical samples. Thus, the morphology of reconstituted F-actin networks is akinetically determined structure similar to those formed by physical gels and glasses. Theseresults establish mechanisms controlling the structure and mechanics in diverse semiflexiblebiopolymer networks.