Investigating the Stepping Mechanism of Myosin X Using Single Molecule Tracking and Building Magnetic Tweezers for the Measurement of Single Cell Mechanics

Abstract

Myosin X, whose dimer was the first to be reported as anti-parallel in myosin family, has been found localized to the tips of filopodia and assisting in the formation of filopodia. As has been reported before, filopodia stimulate varied cells migration, therefore, the structure, stepping mechanism and functions of myosin X are crucial for understanding the detailed signal transduction during cell migrations. Here, I focus on the stepping mechanism of myosin X which has been under heated discussions. By implementing the single molecule tracking method called FIONA, the center of the single myosin X can be localized within nanometer accuracy. I found myosin X has broad distributions of step sizes and frequent backward steps compared to the other members in myosin family, which suggests a unique stepping mechanism on actin bundles along the filopodia.

 

Magnetic tweezers can exert force or torque on biological systems including molecules and cells. It has a much wider force range from pico-newton to nano-newton than the other micromanipulation tools as AFM, optical tweezers. Permanent magnets combined with the fast CMOS camera enable us to investigate the dynamics and mechanics of single DNA. And the magnetic tweezers with electromagnets allow the investigation of mechanics of single cells. I have built a magnetic tweezer with both the permanent magnets and the electromagnet and applied the electromagnet system into measuring cell mechanical properties. The results of cells measurement are consistent with the previous reports.