Origin of tradeoff between movement velocity and attachment duration of kinesin motor on a microtubule

Abstract

Kinesin-1 motor protein is a homodimer containing two identical motor domains connected by a common long coiled-coil stalk via two flexible neck linkers. The motor can step on a microtubule with a velocity of about 1 μm⋅s−1 and an attachment duration of about 1 s under physiological conditions. The available experimental data indicate a tradeoff between velocity and attachment duration under various experimental conditions, such as variation of the solution temperature, variation of the strain between the two motor domains, and so on. However, the underlying mechanism of the tradeoff is unknown. Here, the mechanism is explained by a theoretical study of the dynamics of the motor under various experimental conditions, reproducing quantitatively the available experimental data and providing additional predictions. How the various experimental conditions lead to different decreasing rates of attachment duration versus velocity is also explained.