TRANSITION PATHWAY FOR THE MINUS-END DIRECTED MOVEMENT OF KINESIN-14 NCD

Using Targeted Molecular Dynamics (TMD), we trace the transition pathway of the minus-end directed movement of the Ncd stalk. TMD reveals a number of substeps involved in the rotation of the stalk towards the minus end of microtubules (MT). Our results show that the stalk motion does not possess any directional bias (neither towards the plus or minus end of MT). The minus-end directed movement could thus be due to thermal diffusion between the series of substeps, rather than a rigid body rotation driven by a power stroke. Further tests are necessary to characterize substeps and the relative role played by thermal fluctuation and deterministic motion.