The Research Of Myosin V’s Stationary State And Processive Motion

Molecular motors are nanomachines transporting cargoes in cell and they change the energy of the hydrolysis of ATP into the movement of motors. The motility of molecule motors has became one of the focuses of Biophysics. Molecular motors can be mainly divided into the following four types:myosin, kinesin, dynein, and FIFOATPase. Myosin V is one of the myosin super families and it is an unconventional motor. Among the family of myosin, myosin V has a distinct characteristic; for it walks along the microfilament alone while of the other myosins move forward cooperatively.With the advance of optical tweezers, nanometer fluorescence imaging, and high-speed atomic force microscope, the experiment of myosin V movement has made a lot of progress. Meanwhile, many models have been constructed, such as "Hand-over-Hand" model, "elastic lever arm" model and "multi rigid arm" model. The aim of these models is to explain the characteristic of myosin V in its movement.A directional movement experiences many middle states in a mechanical and chemical cycle. We construct a 4-state mechanochemical model of the myosin V’s processive directional movement. The transitions between two connected of myosin-V take place in a stochastic manner. We can use the master equation and Bell equation to analyze and calculate quantitatively. We obtain an average velocity; an average dwell time, and an average run length. The theoretical curves are generally in line with the experimental data. This work provides a new idea for the characteristic of myosin V.The text includes four parts:Part one briefly introduces the super family of myosin. Part two introduces the experimental and theoretical researches about the directional motion characteristics of myosin V. Part three elaborates the theory describing the 4-state mechanochemical model of the Myosin V, which is the most significant part of this paper. We work it out by the theory of the 4-state mechanochemical model. Theoretical curves are compared with the experimental data. Part four makes a summary and perspective for the future study.