An allosteric mechanism to displace nuclear export cargo from CRM1 and RanGTP by RanBP1
An allosteric mechanism to displace nuclear export cargo from CRM1 and RanGTP by RanBP1
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DOI：
10.1038/emboj.2010.89
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发表时间：
2010-06-16
期刊：
影响因子：
11.4
通讯作者：
Matsuura, Yoshiyuki
中科院分区：
文献类型：
--
作者：
Koyama, Masako;Matsuura, Yoshiyuki
核转运蛋白CRM 1介导携带富含亮氨酸的核输出信号（内斯）的蛋白质和核糖核蛋白的核输出。为了阐明NES-货物在细胞质中从CRM 1解离的精确机制，这对运输方向性很重要，我们确定了酵母CRM 1：RanBP 1：RanGTP复合物的2.0埃分辨率晶体结构，该复合物是CRM 1核输出复合物分解的中间体。结构显示，在RanBP 1的RanBD与CRM 1：NES-货物：RanGTP复合物结合时，RanBD和Ran的C-末端酸性尾诱导CRM 1的HEAT 9内环的大移动。该环移动到紧邻NES结合位点后面的CRM 1内表面，并引起HEAT重复序列11和12中的构象重排，使得CRM 1外表面上的疏水性NES结合裂缝闭合，挤出NES货物。这种变构机制使内斯的解离加速超过两个数量级。基于结构的诱变表明，HEAT 9环也起变构自身抑制剂的作用，以使CRM 1稳定在不存在RanGTP的情况下不能结合NES-货物的构象。EMBO期刊（2010）29，2002-2013。doi：10.1038/doj.2010.89; 2010年5月18日在线发布
The karyopherin CRM1 mediates nuclear export of proteins and ribonucleoproteins bearing a leucine-rich nuclear export signal (NES). To elucidate the precise mechanism by which NES-cargos are dissociated from CRM1 in the cytoplasm, which is important for transport directionality, we determined a 2.0-angstrom resolution crystal structure of yeast CRM1:RanBP1:RanGTP complex, an intermediate in the disassembly of the CRM1 nuclear export complex. The structure shows that on association of Ran-binding domain (RanBD) of RanBP1 with CRM1:NES-cargo:RanGTP complex, RanBD and the C-terminal acidic tail of Ran induce a large movement of the intra-HEAT9 loop of CRM1. The loop moves to the CRM1 inner surface immediately behind the NES-binding site and causes conformational rearrangements in HEAT repeats 11 and 12 so that the hydrophobic NES-binding cleft on the CRM1 outer surface closes, squeezing out the NES-cargo. This allosteric mechanism accelerates dissociation of NES by over two orders of magnitude. Structure-based mutagenesis indicated that the HEAT9 loop also functions as an allosteric autoinhibitor to stabilize CRM1 in a conformation that is unable to bind NES-cargo in the absence of RanGTP. The EMBO Journal (2010) 29, 2002-2013. doi: 10.1038/emboj.2010.89; Published online 18 May 2010