Speaker: William Hancock (Penn State University)
Title: Coordination of the two motor domains in the motor protein Kinesin-2
Abstract: Kinesin-2 motors transport cargo along microtubules both in the cytoplasm of cells and in cilia and flagella. Like many kinesins as well as selected myosin and dynein motors, Kinesin-2 motors are processive, meaning they take many steps per encounter with a microtubule before detaching. This processive walking relies on mechnochemical coordination between the two motor domains. Compared to the canonical Kinesin-1 (conventional kinesin), Kinesin-2 is distinctive in having two different head domains as opposed to two identical motor domains. This heterodimeric structure opens the possibility that the motor properties of the two heads are tuned to optimize motor behavior. The second difference is that the flexible neck linker that connects each head to their shared dimerization domain is longer than in Kinesin-1. Our experimental results suggest that the enhanced compliance resulting from this neck linker extension diminishes the mechanical communication between the two heads. Together with single-molecule experiments on Kinesin-1 and Kinesin-2 motors, we are using stochastic kinetic models as well as molecular dynamics and Brownian Dynamics simulations to understand the entropic spring-like properties of this neck linker domain and its role in kinesin stepping.