Domain interdependence in the biosynthetic assembly of CFTR
Domain interdependence in the biosynthetic assembly of CFTR
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DOI：
10.1016/j.jmb.2006.10.086
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发表时间：
2007-01-26
影响因子：
5.6
通讯作者：
Riordan, John R.
中科院分区：
文献类型：
--
作者：
Cui, Liying;Aleksandrov, Luba;Riordan, John R.
它们的两个核苷酸结合域（NBDs）在所谓的“核苷酸三明治”中二聚化是ATP盒结合（ABC）蛋白的标志，也是它们催化活性的基础。囊性纤维化跨膜传导调节因子（CFTR或ABCC7）的主要致病突变，即NBD1中Phe508的缺失，不会严重改变该结构域的结构，但会阻止整个CFTR蛋白的构象成熟，这可能是通过破坏NBDI之间的天然相互作用，而CFTR折叠中的结构域间相互作用具有NBD2的作用。然而，最近的一份报告对所有CFTR结构域独立折叠提出了质疑。本研究表明，除了结构域折叠外，正确的结构域间组装对于形成满足内质网质量控制的稳定单元至关重要。n端结构域依赖于它们更多的c端邻居，最主要的是第二个跨膜结构域（MSD2），但重要的是，不依赖于NBD2。完全不含NBD2的野生型c端截断结构体被运输出内质网并到达细胞表面，在那里它们以低打开概率形成特有的CFTR氯离子通道。Delta NBD2野生型蛋白成熟并具有与其全长对应蛋白相似的稳定性。因此，催化关键的nbd间关联并不需要满足内质网质量控制机制。Delta F508突变阻止了Delta NBD2的成熟，就像它阻止全长CFTR一样，这表明除了NBD2之外，Delta F508还干扰了分子的其他部分。我们发现突变阻止了紧凑MSD1的形成，这反映在它对蛋白酶消化的易感性上。MSD1的这种扰动可能反过来阻止其与MSD2的正常整合。NBD2在更多n端结构域折叠中的可缺性与已知的NBD2在Delta F508蛋白中对蛋白水解的超敏性形成对比。(c) 2006 Elsevier Ltd.版权所有。
The dimerization of their two nucleotide binding domains (NBDs) in a so-called "nucleotide-sandwich" is the hallmark of ATP cassette binding (ABC) proteins and the basis of their catalytic activities. The major disease-causing mutation in the cystic fibrosis transmembrane conductance regulator (CFTR or ABCC7), deletion of Phe508 in NBD1, does not grossly alter the structure of that domain but prevents conformational maturation of the whole CFTR protein, possibly by disrupting the native interaction between NBDI and the role of inter-domain interactions in CFTR folding has NBD2. However, been brought into question by a recent report that all CFTR domains fold independently. Here we show that in addition to domain folding, correct inter-domain assembly is essential to form a stable unit that satisfies endoplasmic reticulum (ER) quality control. N-terminal domains depend on their more C-terminal neighbors, most essentially the second membrane-spanning domain (MSD2) but significantly, not NBD2. Wild-type C-terminal truncation constructs, completely devoid of NBD2 are transported out of the ER and to the cell surface where they form characteristic CFTR chloride channels with low open probability. The Delta NBD2 wild-type protein matures and has similar stability as its full-length counterpart. Therefore, the catalytically crucial inter-NBD associations are not required to satisfy ER quality control mechanisms. The Delta F508 mutation arrests the maturation of Delta NBD2 just as it does full-length CFTR, indicating that Delta F508 perturbs other portions of the molecule in addition to NBD2. We find that the mutation prevents formation of a compact MSD1, reflected in its susceptibility to protease digestion. This perturbation of MSD1 may in turn prevent its normal integration with MSD2. The dispensability of NBD2 in the folding of more N-terminal domains stands in contrast to the known hypersensitivity to proteolysis of NBD2 in the Delta F508 protein. (c) 2006 Elsevier Ltd. All rights reserved.