A small processivity of kinesin-14 motors can enhance sliding velocity of antiparallel microtubules.

Members of kinesin-14 family motors, which can move toward the microtubule (MT) minus end, play roles in spindle assembly and maintenance during mitosis and meiosis. Some kinesin-14 motors are non-processive while others are processive. Here, we study both theoretically and numerically the dynamics of the MT gliding and relative sliding of antiparallel MTs by multiple kinesin-14 motors. We show that while the published experimental data on the MT gliding and sliding by multiple kinesin-14 HSET motors cannot be explained by considering that the HSET is non-processive, they are well explained by a model in which HSET has a small processivity. More interestingly, we find that an optimal small processivity of the kinesin-14 motor is present, under which the MT sliding by the multiple motors can attain maximal velocity. Moreover, we show that the non-processive motors have an evidently larger ability to accumulate at the minus ends of parallel MTs than the processive motors of even a very small processivity. These imply that while the kinesin-14 motors of the small processivity are more likely to function as maintaining antiparallel MTs in spindles, the non-processive motors are more likely to function as anchoring nearly parallel MTs at their minus ends to form spindle poles.