We are interested in uncovering how different kinesin motor proteins are optimized for their cellular tasks. Because the kinesin walking mechanism involves two motor domains working in a coordinated manner, we have focused our efforts on understanding the Kinesin-2 family of motors that contain two distinct motor domains instead of the normal homodimer arrangement. As these motors are necessary for the formation of cilia and flagella, the study of Kinesin-2 motors impacts a wide range of important cell biological questions and pathologies including developmental defects, polycystic kidney disease, and defects in flagellar motility.
We have generated a number of mutant and chimaeric Kinesin-2 motors, and we are using single-molecule fluorescence experiments, optical tweezer studies, biochemical assays and computational modeling to understand the chemomechanical cycle underlying Kinesin-2 walking. See Motility Assay page for a description of some of these assays.
Mechanics of the Kinesin Neck Linker Domain. The neck linker domain connects each head to the coiled coil and serves three important functions as described. Diverse kinesins have neck linkers ranging from 14 to 18 amino acids, which is predicted to alter the transmission of force between the two motor domains.
Recently, this work has focused on the role of the flexible neck linker domain, a sequence of 14-18 amino acids that connects the catalytic motor domain to the coiled-coil rod domain. We found that the ability of Kinesin-2 as well as other diverse kinesins to walk long distances without detaching (motor processivity) is regulated by the length of the neck linker domain (1-3). We are currently focusing our efforts on understanding the precise biochemical steps in the hydrolysis cycle that are altered by inter-head tension.
1. Muthukrishnan, G., Zhang, Y., Shastry, S., and Hancock, W.O. (2009). The processivity of kinesin-2 motors suggests diminished front-head gating. Current Biology 19(5), 442-447. Supplemental Data.
2. Shastry, S., and Hancock, W.O. (2010). Neck linker length determines the degree of processivity in Kinesin-1 and Kinesin-2 motors. Current Biology 20, 939-943. Supplemental Data.
3. Shastry, S., and Hancock, W.O. (2011). Interhead tension determines processivity across diverse N-terminal kinesins. Proc Natl Acad Sci U S A 108, 16253-16258.