Plus end-specific depolymerase activity of Kip3, a kinesin-8 protein, explains its role in positioning the yeast mitotic spindle
Plus end-specific depolymerase activity of Kip3, a kinesin-8 protein, explains its role in positioning the yeast mitotic spindle
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DOI：
10.1038/ncb1457
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发表时间：
2006-09-01
影响因子：
21.3
通讯作者：
Pellman, David
中科院分区：
文献类型：
--
作者：
Gupta, Mohan L., Jr.;Carvalho, Pedro;Pellman, David
发芽酵母蛋白Kip3p是微管-皮质相互作用、正常纺锤体组装和动粒动力学所必需的保守的kinesin-8微管马达家族成员。在这里，我们证明了Kip3p既是一个正端导向的运动，也是一个正端特异的解聚酶--这是其他动蛋白中没有的一种独特的活性组合。Kip3p的ATPase活性可被微管和未聚合微管蛋白激活。此外，Kip3p在三磷酸腺苷结合态与未聚合的微管蛋白形成复合体。因此，运动性Kinesin-8s可能通过与非运动性Kinesin-13蛋白类似的机制解聚微管。荧光散斑分析证实，在体内，Kip3p向生长的微管的正端移动并积累，表明运动活动将Kip3p带到其作用部位。在全球范围内，在皮质接触方面，Kip3p促进了灾难和停顿，并抑制了微管的生长。这些发现解释了Kip3p在发芽酵母中定位有丝分裂纺锤体的作用，以及可能由kinesin-8家族成员控制的其他过程。
The budding yeast protein Kip3p is a member of the conserved kinesin-8 family of microtubule motors, which are required for microtubule -cortical interactions, normal spindle assembly and kinetochore dynamics. Here, we demonstrate that Kip3p is both a plus end-directed motor and a plus end-specific depolymerase - a unique combination of activities not found in other kinesins. The ATPase activity of Kip3p was activated by both microtubules and unpolymerized tubulin. Furthermore, Kip3p in the ATP-bound state formed a complex with unpolymerized tubulin. Thus, motile kinesin-8s may depolymerize microtubules by a mechanism that is similar to that used by non-motile kinesin-13 proteins. Fluorescent speckle analysis established that, in vivo, Kip3p moved toward and accumulated on the plus ends of growing microtubules, suggesting that motor activity brings Kip3p to its site of action. Globally, and more dramatically on cortical contact, Kip3p promoted catastrophes and pausing, and inhibited microtubule growth. These findings explain the role of Kip3p in positioning the mitotic spindle in budding yeast and potentially other processes controlled by kinesin-8 family members.