Regulation of mitotic spindle assembly factor NuMA by Importin-β.
Regulation of mitotic spindle assembly factor NuMA by Importin-β.
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DOI：
10.1083/jcb.201705168
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发表时间：
2017-11-06
期刊：
影响因子：
--
通讯作者：
Hsia KC
中科院分区：
文献类型：
--
作者：
Chang CC;Huang TL;Shimamoto Y;Tsai SY;Hsia KC
NuMA已被建议作为一个Ran-regulated主轴组装因子，调制主轴磁极组装。Chang等人提供的结构和生物化学证据表明，NuMA含有一个Importin-β调节的微管结合区，该区域允许Ran调节组装高阶微管结构所需的NuMA功能。Ran-guanosine triphosphatase通过调节Importin-α/-β和纺锤体组装因子（SAF）之间的相互作用来协调有丝分裂纺锤体组装。由输入蛋白进行的SAF的抑制需要在没有来自丰富的含核定位信号（NLS）的蛋白的大量螯合的情况下进行。然而，决定NLS结合选择性和抑制输入蛋白-β调节的SAF活性的分子机制（例如，核有丝分裂器蛋白[NuMA]）仍然不确定。在这里，我们展示了Importin-α-NuMA C末端复合物的晶体结构，显示了一种新的结合模式，可解释选择性NLS识别。我们证明，在Importin-α存在下，Importin-β抑制NuMA的微管结合功能。此外，我们已经鉴定了位于NLS羧基末端的高亲和力微管结合区，其在被Importin-α结合时被Importin-β空间掩蔽。我们的研究提供了Importin-α/-β如何调节组装高阶微管结构所需的NuMA功能的机制证据，进一步阐明了Ran调控的转运因子如何调节不同的SAF并适应各种细胞需求。
NuMA has been suggested to function as a Ran-regulated spindle assembly factor that modulates spindle pole assembly. Chang et al. provide structural and biochemical evidence showing that NuMA contains an Importin-β–regulated microtubule-binding region, which allows Ran to regulate the NuMA functions required for the assembly of higher-order microtubule structures. Ran–guanosine triphosphatase orchestrates mitotic spindle assembly by modulation of the interaction between Importin-α/-β and spindle assembly factors (SAFs). The inhibition of SAFs performed by importins needs to be done without much sequestration from abundant nuclear localization signal (NLS) –containing proteins. However, the molecular mechanisms that determine NLS-binding selectivity and that inhibit activity of Importin-β–regulated SAFs (e.g., nuclear mitotic apparatus protein [NuMA]) remain undefined. Here, we present a crystal structure of the Importin-α–NuMA C terminus complex showing a novel binding pattern that accounts for selective NLS recognition. We demonstrate that, in the presence of Importin-α, Importin-β inhibits the microtubule-binding function of NuMA. Further, we have identified a high-affinity microtubule-binding region that lies carboxyl-terminal to the NLS, which is sterically masked by Importin-β on being bound by Importin-α. Our study provides mechanistic evidence of how Importin-α/-β regulates the NuMA functioning required for assembly of higher-order microtubule structures, further illuminating how Ran-governed transport factors regulate diverse SAFs and accommodate various cell demands.
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DOI：
10.1074/jbc.m110.102343
发表时间：
2010-06-04
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Giesecke A;Stewart M
通讯作者：
Stewart M
影响因子：
5.6
作者：
Fontes, MRM;Teh, T;Kobe, B
通讯作者：
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影响因子：
64.5
作者：
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通讯作者：
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DOI：
10.1107/s0907444998003254
发表时间：
1998-09-01
期刊：
ACTA CRYSTALLOGRAPHICA SECTION D-BIOLOGICAL CRYSTALLOGRAPHY
影响因子：
--
作者：
Brunger, AT;Adams, PD;Warren, GL
通讯作者：
Warren, GL
影响因子：
64.5
作者：
Nachury, MV;Maresca, TJ;Weis, K
通讯作者：
Weis, K