B CUBE-Center for Molecular Bioengineering, Technische Universität Dresden, 01307, Dresden, Germany.
Max Planck Institute of Molecular Cell Biology and Genetics, 01307, Dresden, Germany.
Nat Commun. 2020 May 22;11(1):2565. doi: 10.1038/s41467-020-16328-z.
Within the mitotic spindle, kinesin motors cross-link and slide overlapping microtubules. Some of these motors exhibit off-axis power strokes, but their impact on motility and force generation in microtubule overlaps has not been investigated. Here, we develop and utilize a three-dimensional in vitro motility assay to explore kinesin-14, Ncd, driven sliding of cross-linked microtubules. We observe that free microtubules, sliding on suspended microtubules, not only rotate around their own axis but also move around the suspended microtubules with right-handed helical trajectories. Importantly, the associated torque is large enough to cause microtubule twisting and coiling. Further, our technique allows us to measure the in situ spatial extension of the motors between cross-linked microtubules to be about 20 nm. We argue that the capability of microtubule-crosslinking kinesins to cause helical motion of overlapping microtubules around each other allows for flexible filament organization, roadblock circumvention and torque generation in the mitotic spindle.
在有丝分裂纺锤体中，驱动蛋白马达交联并滑动重叠的微管。其中一些马达表现出离轴力作用，但它们对微管重叠处的运动和力的产生的影响尚未被研究。在这里，我们开发并利用了一种三维体外运动分析方法来探索动力蛋白-14，Ncd 驱动交联微管的滑动。我们观察到，在悬挂微管上滑动的游离微管不仅绕自身轴旋转，而且还绕悬挂微管以右旋螺旋轨迹运动。重要的是，相关的扭矩足以导致微管扭曲和缠绕。此外，我们的技术使我们能够测量交联微管之间马达的原位空间延伸，约为 20nm。我们认为，微管交联驱动蛋白使重叠微管彼此之间发生螺旋运动的能力允许有丝分裂纺锤体中灵活的纤维组织、回避障碍物和产生扭矩。
