The role of the Arp2/3 complex in shaping the dynamics and structures of branched actomyosin networks

Significance Networks of actin filaments form the structural scaffold of cells. Energy-consuming protein motors such as the myosins that exert forces on the network by “walking” on actin filaments as well as polymerization of actin polymers are necessary for the movement, growth, and division of cells. The dynamics of actomyosin networks is regulated by actin-binding proteins. One of the most important of these binding proteins is the actin-related protein 2/3 (Arp2/3) complex that nucleates branched filaments, thereby altering network topology. In this work, we simulated the dynamics of actomyosin networks both with and without Arp2/3 complexes. The branched networks with Arp2/3 exhibit rare convulsive movements, which we call “avalanches,” that are reminiscent of recent experimental reports of “cytoquakes.”