Mechanism of High-Efficient Microtubule Gliding and Low-Efficient Microtubule Sliding by Kinesin-14 Ncd Molecular Motors

Ncd is the founding member of the kinesin-14 family, which can move on microtubules toward the minus end in a nonprocessive manner by hydrolyzing ATP molecules. It was experimentally observed that while multiple anchored Ncd motors can drive the gliding of a microtubule with high efficiency, the full-length Ncd motors can drive the sliding of one microtubule relative to the antiparallel one with a much lower efficiency. However, a quantitative explanation of these experimental results is not available. The mechanism of how the microtubule sliding by the full-length Ncd motors has much lower efficiency than the microtubule gliding by the anchored Ncd motors is unclear. Here, we use both theoretical analysis and numerical simulation to study microtubule gliding and sliding by the Ncd motors, explaining quantitatively the available experimental data. The studies show that the competition between the motor's stalk rotation and its tail diffusion results in the much lower efficiency of the microtubule sliding than that of the microtubule gliding. This mechanism of the lower efficiency of microtubule sliding by the Ncd motors is different from the previously proposed mechanism of the nonefficient microtubule gliding by kinesin-1 motors anchored to the slippery surface.