Role of the Actin–Myosin Catch Bond on Actomyosin Aggregate Formation

Abstract

Actin and myosin, which are key components of contractile machinery, are responsible for cell shape changes, movement, and tissue deformation during morphogenesis. To generate contractile forces, actin and myosin combine to form aggregates with functional structures. On the molecular scale, because the actin–myosin catch-bond behavior reinforces the actin–myosin bond when the force exerted on the bond increases, actin–myosin kinetics is likely modulated by the actomyosin-generated force as well as the external force. The catch-bond behavior is anticipated to couple the mechanical and kinetic aspects of actomyosin aggregate formation. In this study, to unveil new aspects of actomyosin aggregate formation, we employed two mathematical models based on coarse-grained particle dynamics that describe actomyosin dynamics with and without the catch bond. Comparing the computational simulation results obtained from two models, we observed that the catch-bond behavior assists in the assemblage of myosin in a random actomyosin network even at low myosin concentrations and accelerates the completion of aggregate formation at relatively higher concentrations. The actin–myosin catch bond is anticipated to support foci formation from a random actomyosin network at the cell cortex during morphogenesis.