Simulating an Actomyosin in Vitro Motility Assay: Toward the Rational Design of Actomyosin-Based Microtransporters

We present a simulation study of an actomyosin in vitro motility assay. In vitro motility assays have served as an essential element facilitating the application of actomyosin in nanotechnology; such applications include biosensors and biocomputation. Although actomyosin in vitro motility assays have been extensively investigated, some ambiguities remain, as a result of the limited spatio-temporal resolution and unavoidable uncertainties associated with the experimental process. These ambiguities hamper the rational design of nanodevices for practical applications. Here, with the aim of moving toward a rational design process, we developed a 3D computer simulation method of an actomyosin in vitro motility assay, based on a Brownian dynamics simulation. The simulation explicitly included the ATP hydrolysis cycle of myosin. The simulation was validated by the reproduction of previous experimental results. More importantly, the simulation provided new insights that are difficult to obtain experimentally, including data on the number of myosin motors actually binding to actin filaments, the mechanism responsible for the guiding of actin filaments by chemical edges, and the effect of the processivity of motor proteins on the guiding probabilities. The simulations presented here will be useful in interpreting experimental results, and also in designing future nanodevices integrated with myosin motors.