EB1 regulates microtubule dynamics and tubulin sheet closure in vitro
EB1 regulates microtubule dynamics and tubulin sheet closure in vitro
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DOI：
10.1038/ncb1703
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发表时间：
2008-04-01
影响因子：
21.3
通讯作者：
Arnal, Isabelle
中科院分区：
文献类型：
--
作者：
Vitre, Benjamin;Coquelle, Frederic M.;Arnal, Isabelle
末端结合1 （End binding 1, EB1）是一种+端跟踪蛋白（+TIP），定位于微管+端，调节微管+端动力学和与胞内细胞器的相互作用（1,2）。虽然已经在细胞（3-6）和纯化系统（7-13）中研究了EB1对微管动力学的调节活性，但其特异性活性所涉及的分子机制仍不清楚。在这里，我们描述了EB1如何调节由纯微管蛋白组装的微管的动力学和结构。我们发现EB1刺激微管的自发成核和生长，并促进灾难（从生长到收缩的转变）和拯救（逆转事件）。电子冷冻显微镜显示，EB1诱导微管蛋白片的初始形成，并迅速接近常见的13-原丝-微管结构。我们的研究结果表明，EB1有利于游离微管蛋白在微管片边缘的横向结合，从而刺激微管片的成核、生长和关闭。微管生长端薄片长度的减少和微管晶格的消除可能是灾难的原因。相反，偶尔EB1与微管晶格的结合可能会引起拯救。
End binding 1 ( EB1) is a plus-end-tracking protein (+TIP) that localizes to microtubule plus ends where it modulates their dynamics and interactions with intracellular organelles(1,2). Although the regulating activity of EB1 on microtubule dynamics has been studied in cells(3-6) and purified systems(7-13), the molecular mechanisms involved in its specific activity are still unclear. Here, we describe how EB1 regulates the dynamics and structure of microtubules assembled from pure tubulin. We found that EB1 stimulates spontaneous nucleation and growth of microtubules, and promotes both catastrophes ( transitions from growth to shrinkage) and rescues ( reverse events). Electron cryomicroscopy showed that EB1 induces the initial formation of tubulin sheets, which rapidly close into the common 13-protofilament-microtubule architecture. Our results suggest that EB1 favours the lateral association of free tubulin at microtubule-sheet edges, thereby stimulating nucleation, sheet growth and closure. The reduction of sheet length at microtubule growing-ends together with the elimination of stressed microtubule lattices may account for catastrophes. Conversely, occasional binding of EB1 to the microtubule lattice may induce rescues.