Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon 97331, USA.
Department of Physics, Oregon State University, Corvallis, Oregon 97331, USA.
Nat Commun. 2017 Jan 4;8:13999. doi: 10.1038/ncomms13999.
Kinesin-14s are commonly known as nonprocessive minus end-directed microtubule motors that function mainly for mitotic spindle assembly. Here we show using total internal reflection fluorescence microscopy that KlpA-a kinesin-14 from Aspergillus nidulans-is a context-dependent bidirectional motor. KlpA exhibits plus end-directed processive motility on single microtubules, but reverts to canonical minus end-directed motility when anchored on the surface in microtubule-gliding experiments or interacting with a pair of microtubules in microtubule-sliding experiments. Plus end-directed processive motility of KlpA on single microtubules depends on its N-terminal nonmotor microtubule-binding tail, as KlpA without the tail is nonprocessive and minus end-directed. We suggest that the tail is a de facto directionality switch for KlpA motility: when the tail binds to the same microtubule as the motor domain, KlpA is a plus end-directed processive motor; in contrast, when the tail detaches from the microtubule to which the motor domain binds, KlpA becomes minus end-directed.
驱动蛋白-14 通常被称为非向前的负端指向微管马达，主要用于有丝分裂纺锤体的组装。在这里，我们使用全内反射荧光显微镜显示，来自 Aspergillus nidulans 的 KlpA-一种驱动蛋白-14-是一种依赖于上下文的双向马达。KlpA 在单根微管上表现出正向的、连续的运动，但在微管滑行实验中锚定在表面上或在微管滑动实验中与一对微管相互作用时，它会恢复到典型的负端指向运动。KlpA 在单根微管上的正向连续运动依赖于其 N 端非马达微管结合尾，因为没有尾的 KlpA 是非连续的且负端指向的。我们认为，尾是 KlpA 运动的实际方向开关：当尾与马达域结合的微管相同时，KlpA 是正向连续的马达；相反，当尾从马达域结合的微管上脱离时，KlpA 变成负端指向的。
