Actin filament severing by vertebrate cofilin is driven by linked cation release
Résumé
The dynamic remodeling of actin cytoskeleton drives cell movement. The essential actin regulatory protein cofilin accelerates actin remodeling by severing filaments and increasing the concentration of free filament ends from which subunits add and dissociate. Cofilin binding dissociates actin-associated cations and enhances filament bending and twisting compliance. The linkage between cofilin-mediated cation release, filament mechanics and severing activity has not been firmly established. Here, we demonstrate that cofilin-dependent cation release from a discrete, filament-specific cation binding site enhances the bending and twisting flexibility of actin filaments and that this local change in filament mechanics is required for severing.