Orchestrated electrostatic interactions among myosin, actin, ATP, and water

Abstract

The electrostatic interactions are deeply involved in the force-generating function of the actomyosin molecular motor where myosin, actin, ATP, and water are interacting with each other in a orchestrated manner. In this chapter, an electrostatic perspective is presented based on our recent molecular dynamics simulation studies on the force-generation mechanisms of the actomyosin molecular motor. First, as an unusual property of the electrostatic interaction in water, thermodynamics of association between oppositely singed charges is addressed. Then, our computational results regarding the electrostatic interaction between myosin and actin are described, featuring a sawtooth-like asymmetric energy landscape on which myosin generates forces by multiple mechanisms including the Brownian ratchet-like mechanism. Then the role of ATP is discussed, with a focus on "dielectric allostery" that we found in myosin as an allosteric response to the ATP binding, which serves as weakening the actin-myosin electrostatic interaction and causes myosin to dissociate from actin. Finally, the role of water is discussed from the viewpoint of the association thermodynamics of biomolecules.