Du Kai, Sharma Manu, Lukacs Gergely L
Hospital for Sick Children Research Institute, Program in Cell and Lung Biology, University of Toronto, Ontario M5G 1X8, Canada.
Nat Struct Mol Biol. 2005 Jan;12(1):17-25. doi: 10.1038/nsmb882. Epub 2004 Dec 26.
Misfolding accounts for the endoplasmic reticulum-associated degradation of mutant cystic fibrosis transmembrane conductance regulators (CFTRs), including deletion of Phe508 (DeltaF508) in the nucleotide-binding domain 1 (NBD1). To study the role of Phe508, the de novo folding and stability of NBD1, NBD2 and CFTR were compared in conjunction with mutagenesis of Phe508. DeltaF508 and amino acid replacements that prevented CFTR folding disrupted the NBD2 fold and its native interaction with NBD1. DeltaF508 caused limited alteration in NBD1 conformation. Whereas nonpolar and some aliphatic residues were permissive, charged residues and glycine compromised the post-translational folding and stability of NBD2 and CFTR. The results suggest that hydrophobic side chain interactions of Phe508 are required for vectorial folding of NBD2 and the domain-domain assembly of CFTR, representing a combined co- and post-translational folding mechanism that may be used by other multidomain membrane proteins.
错误折叠导致突变型囊性纤维化跨膜传导调节因子（CFTR）在内质网相关降解，包括核苷酸结合结构域1（NBD1）中苯丙氨酸508（F508）的缺失。为了研究苯丙氨酸508的作用，结合对苯丙氨酸508的诱变，比较了NBD1、NBD2和CFTR的从头折叠和稳定性。F508缺失以及阻止CFTR折叠的氨基酸替代破坏了NBD2的折叠及其与NBD1的天然相互作用。F508导致NBD1构象的有限改变。虽然非极性和一些脂肪族残基是允许的，但带电荷的残基和甘氨酸会损害NBD2和CFTR的翻译后折叠及稳定性。结果表明，苯丙氨酸508的疏水侧链相互作用是NBD2的定向折叠和CFTR的结构域-结构域组装所必需的，这代表了一种可能被其他多结构域膜蛋白利用的共翻译和翻译后折叠联合机制。
