Abstract:
Microtubules and kinesin motor proteins are involved in intracellular transports in living cells.
Such intracellular material transport systems can be reconstructed for utilisation in synthetic
environments, and they are called molecular shuttles driven by kinesin motors. The performance of
the molecular shuttles depends on the nature of their trajectories, which can be characterized by the
path persistence length of microtubules. It has been theoretically predicted that the path persistence
length should be equal to the flament persistence length of the microtubules, where the flament
persistence length is a measure of microtubule fexural stifness. However, previous experiments have
shown that there is a signifcant discrepancy between the path and flament persistence lengths. Here,
we showed how this discrepancy arises by using computer simulation. By simulating molecular shuttle
movements under external forces, the discrepancy between the path and flament persistence lengths
was reproduced as observed in experiments. Our close investigations of molecular shuttle movements
revealed that the part of the microtubules bent due to the external force was extended more than it
was assumed in the theory. By considering the extended length, we could elucidate the discrepancy.
The insights obtained here are expected to lead to better control of molecular shuttle movements.
