All-Atom Simulations of Actin-Myosin Interactions --- A Comparative Study of Cardiac Alpha Myosin, Beta Myosin and Skeletal Muscle Myosin

Abstract

To explore the structural and energetic basis of actin-myosin interactions, we have performed intensive all-atom molecular dynamics simulations followed by free energy calculations & partitions for three types of myosins (cardiac alpha myosin, beta myosin and skeletal muscle myosin). We constructed atomistic models for acomyosin complex in the rigor state by fitting models of myosin and three actin subunits into the cryo-EM map of myosin-decorated filamentous actin. A total of 100ns molecular dynamics simulations were performed for each actomyosin system. We have identified a set of key residues critically involved in actin-myosin binding --- many of them are highly conserved or implicated in mutations that cause hypertrophic cardiomyopathy. The calculated actin-binding affinities are in good agreement with the experimental finding of higher affinity for cardiac beta myosin than alpha myosin and skeletal muscle myosin.