Nie Lingyun, Liu Wenyue, Liang Zhuobi, Zheng Fan, Liu Xing, Yao Xuebiao, Xiang Shengqi, Jiang Kai, Zheng Shengnan, Fu Chuanhai
MOE Key Laboratory for Cellular Dynamics and Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230027, China.
Anhui Key Laboratory of Chemical Biology and New Quality Medicine & Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, 230027, China.
Sci Adv. 2025 Jan 3;11(1):eadq0670. doi: 10.1126/sciadv.adq0670.
Microtubule assembly takes place at the centrosome and noncentrosomal microtubule-organizing centers (MTOCs). However, the mechanisms controlling the activity of noncentrosomal MTOCs are poorly understood. Here, using the fission yeast as a model organism, we demonstrate that the kinesin-14 motor Klp2 interacts with the J-domain Hsp70/Ssa1 cochaperone Rsp1, an inhibitory factor of microtubule assembly, and that Klp2 is required for the proper localization of Rsp1 to microtubules. In addition, we demonstrate that Klp2 is not required for the localization of Mto1, a factor promoting microtubule assembly, to microtubules. Moreover, Rsp1-Ssa1 inhibits the interaction of Mto1-Mto2 with the gamma-tubulin small complex. The absence of Klp2 reduces the colocalization of Rsp1 and Mto1 foci on preexisting microtubules, resulting in an increased microtubule-dependent microtubule assembly. Our results suggest that Klp2 regulates the activity of noncentrosomal MTOCs by targeting Rsp1 to the sites of Mto1 activity and reveal a mechanism for the inhibition of noncentrosomal microtubule assembly by a kinesin-14 motor.
微管组装发生在中心体和非中心体微管组织中心（MTOC）。然而，控制非中心体MTOC活性的机制却知之甚少。在这里，我们以裂殖酵母为模式生物，证明驱动蛋白-14马达蛋白Klp2与J结构域热休克蛋白70 / Ssa1共伴侣Rsp1相互作用，Rsp1是微管组装的抑制因子，并且Klp2是Rsp1正确定位于微管所必需的。此外，我们证明Klp2对于促进微管组装的因子Mto1定位于微管不是必需的。而且，Rsp1 - Ssa1抑制Mto1 - Mto2与γ-微管蛋白小复合体的相互作用。Klp2的缺失减少了Rsp1和Mto1焦点在预先存在的微管上的共定位，导致微管依赖性微管组装增加。我们的结果表明，Klp2通过将Rsp1靶向Mto1活性位点来调节非中心体MTOC的活性，并揭示了一种由驱动蛋白-14马达蛋白抑制非中心体微管组装的机制。
