Force and phosphate release from Arp2/3 complex promote dissociation of actin filament branches
Nandan G. Pandit, Wenxiang Cao, Jeffrey P. Bibeau, Eric M. Johnson-Chavarria, Edwin W. Taylor, Thomas D. Pollard, Enrique M. De La Cruz
Abstract
Significance Arp2/3 complex is an ATPase that binds to the side of a preexisting actin filament and nucleates an actin filament branch. Growing branched networks experience variable resistance and respond by adapting growth speed, power, and architecture. How force influences the dissociation of actin filament branches was not known. We used microfluidics to show that mechanical force promotes the dissociation of actin filament branches and that Arp2/3 complex adopts two distinct mechanical states with different responses to force. Phosphate release from Arp2/3 complex increases the sensitivity to both force and the debranching protein GMF. Thus, phosphate release from Arp2/3 complex may regulate debranching by force and debranching proteins.