Structural study of the HIV1 gp41 coat protein

gp 41构建体的截短刚好超过其跨膜结构域，留下残基1-190，产生结构良好的蛋白质，可溶于十二烷基麦芽糖苷，同时采用其天然的同源三聚体形式。 发现该蛋白质即使在50 ℃的温度下也相当稳定，并且发现样品适用于NMR光谱。 初步分析表明，即使胞外结构域共振严重加宽，具有缓慢分子翻滚的特征，三聚体的融合结构域也产生良好的NMR光谱特征。我们发现，这些融合结构域表现出的化学位移落在非常接近的孤立的域，以前在SDS胶束中研究，并发现是均匀的α-螺旋。融合结构域表现出的有效相关时间比大的三聚体复合物的其余部分短得多，表明完整的融合结构域螺旋在洗涤剂胶束内是高度移动的，同时保留其螺旋构象。这排除了先前假设的与gp 41跨膜结构域的相互作用。

Truncation of the gp41 construct just past its transmembrane domain, leaving residues 1-190, results in a well-structured protein, soluble in dodecylmaltoside while adopting its natural homo-trimeric form. The protein is found to be quite stable, even at temperatures of 50C, and samples are found to be suitable for NMR spectroscopy. Preliminary analysis shows that even thought the ecto-domain resonances are severely broadened, characteristic of slow molecular tumbling, the fusion domains of the trimer yield good NMR spectral characteristics. We find that these fusion domains exhibit chemical shifts that fall very close to those of the isolated domain, previously studied in SDS micelles and found to be uniformly alpha-helical. The fusion domains exhibit effective correlation times that are much shorter than for the remainder of the large trimeric complex, indicating that the intact fusion domain helices are highly mobile within the detergent micelle, while retaining their helical conformation. This excludes the previously hypothesized interaction with the gp41 transmembrane domain.