Structural basis for the activation of microtubule assembly by the EB1 and p150Glued complex
Structural basis for the activation of microtubule assembly by the EB1 and p150Glued complex
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DOI：
10.1016/j.molcel.2005.06.034
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发表时间：
2005-08-19
期刊：
影响因子：
16
通讯作者：
Ikura, M
中科院分区：
文献类型：
--
作者：
Hayashi, I;Wilde, A;Ikura, M
正末端跟踪蛋白，如EB 1和动力蛋白/动力蛋白复合物，调节微管动力学。这些蛋白质被认为是稳定微管;通过在微管生长末端形成一个正末端复合物，其机制尚不清楚。在这里，我们报告的晶体结构的两个加端复杂的组件，羧基末端二聚化结构域的EB 1和微管结合（CAP-Gly）结构域的dynactin亚基p150（胶合）。EB 1二聚体的每个分子包含两个螺旋，形成保守的四螺旋束，同时还在其柔性尾部区域提供p150（胶合）结合位点。结合晶体学，NMR和突变分析，我们的研究揭示了EB 1和p150（Glued）的关键相互作用元素，其突变改变微管聚合活性。此外，从EB 1中去除关键的柔性尾激活了EB 1单独的微管组装，这表明柔性尾负调节EB 1活性。因此，我们提出，EB 1具有自抑制的构象，这是由p150（Glued）作为变构激活剂缓解。
Plus-end tracking proteins, such as EB1 and the dynein/dynactin complex, regulate microtubule dynamics. These proteins are thought to stabilize microtubules; by forming a plus-end complex at microtubule growing ends with ill-defined mechanisms. Here we report the crystal structure of two plus-end complex components, the carboxy-terminal dimerization domain of EB1 and the microtubule binding (CAP-Gly) domain of the dynactin subunit p150(Glued). Each molecule of the EB1 dimer contains two helices forming a conserved four-helix bundle, while also providing p150(Glued) binding sites in its flexible tail region. Combining crystallography, NMR, and mutational analyses, our studies reveal the critical interacting elements of both EB1 and p150(Glued), whose mutation alters microtubule polymerization activity. Moreover, removal of the key flexible tail from EB1 activates microtubule assembly by EB1 alone, suggesting that the flexible tail negatively regulates EB1 activity. We, therefore, propose that EB1 possesses an autoinhibited conformation, which is relieved by p150(Glued) as an allosteric activator.