Alteration of CFTR transmembrane span integration by disease-causing mutations.
Alteration of CFTR transmembrane span integration by disease-causing mutations.
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DOI：
10.1091/mbc.e11-05-0396
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发表时间：
2011-12
影响因子：
3.3
通讯作者：
Thomas PJ
中科院分区：
文献类型：
--
作者：
Patrick AE;Karamyshev AL;Millen L;Thomas PJ
CF跨膜传导调节蛋白的第一跨膜跨度中的两个引起囊性纤维化的突变具有不同的分子病理学。这些结果对于理解膜蛋白整合和折叠的机制以及致病突变体的影响具有重要意义。囊性纤维化跨膜传导调节蛋白（CFTR）中的许多错义突变导致其错误折叠，内质网（ER）积聚，并因此导致囊性纤维化。许多这些突变位于预测的CFTR跨膜（TM）跨度，并已预计改变跨度整合。然而，跨度的边界还没有被精确地定义实验。在这项研究中，使用ER糖基化机制确定了TM1和TM2的ER管腔整合谱，并评估了引起CF的突变G85E和G91R对其的影响。突变或者使整合构象不稳定或者改变TM1 ER整合谱。G85 E错误折叠是基于TM1谷氨酸和甘氨酸的损失不稳定，并与温度不敏感的ER积累的不成熟的全长CFTR窝藏突变。相比之下，由于G91R突变引起的温度依赖性错误折叠取决于碱性侧链的引入，而不是甘氨酸的丢失。这项工作表明，预测对CFTR结构具有类似影响的CF引起突变实际上导致了不同的分子扰动，这些分子扰动是ER积累和CF病理学的基础。
There are distinct molecular pathologies for two cystic fibrosis–causing mutations in the first transmembrane span of the CF transmembrane conductance regulator protein. These results have implications for understanding the mechanisms of membrane protein integration and folding and the effects of disease-causing mutants. Many missense mutations in the cystic fibrosis transmembrane conductance regulator protein (CFTR) result in its misfolding, endoplasmic reticulum (ER) accumulation, and, thus, cystic fibrosis. A number of these mutations are located in the predicted CFTR transmembrane (TM) spans and have been projected to alter span integration. However, the boundaries of the spans have not been precisely defined experimentally. In this study, the ER luminal integration profiles of TM1 and TM2 were determined using the ER glycosylation machinery, and the effects of the CF-causing mutations G85E and G91R thereon were assessed. The mutations either destabilize the integrated conformation or alter the TM1 ER integration profile. G85E misfolding is based in TM1 destabilization by glutamic acid and loss of glycine and correlates with the temperature-insensitive ER accumulation of immature full-length CFTR harboring the mutation. By contrast, temperature-dependent misfolding owing to the G91R mutation depends on the introduction of the basic side chain rather than the loss of the glycine. This work demonstrates that CF-causing mutations predicted to have similar effects on CFTR structure actually result in disparate molecular perturbations that underlie ER accumulation and the pathology of CF.