Burmann Björn M, Hiller Sebastian
University of Basel Biozentrum Klingelbergstr. 70 CH-4056 Basel, Switzerland.
Chimia (Aarau). 2012;66(10):759-63. doi: 10.2533/chimia.2012.759.
The biosynthesis of the bacterial outer membrane depends on molecular chaperones that protect hydrophobic membrane proteins against aggregation while transporting them across the periplasm. In our ongoing research, we use high-resolution NMR spectroscopy in aqueous solution as the main technique to characterize the structures and biological functions of these membrane-protein-chaperone complexes. Here, we describe NMR studies addressing three functional aspects of periplasmic membrane-protein-chaperone complexes. Firstly, the Escherichia coli outer membrane protein OmpX binds to each of the two chaperones, Skp and SurA, in structurally at least partially similar states despite fundamental differences between the three-dimensional structures of the chaperones. Secondly, we show that the Skp-bound state of OmpX is equivalent to a chemically denatured state in terms of its refolding competence into detergent micelles in vitro. Thirdly, we use amino acid mutation analysis to show that the interaction of OmpX to Skp is not dominated by the two most hydrophobic segments of OmpX.
细菌外膜的生物合成依赖于分子伴侣，这些分子伴侣在将疏水性膜蛋白跨周质转运时保护它们不发生聚集。在我们正在进行的研究中，我们使用水溶液中的高分辨率核磁共振光谱作为主要技术来表征这些膜蛋白 - 伴侣复合物的结构和生物学功能。在这里，我们描述了针对周质膜蛋白 - 伴侣复合物三个功能方面的核磁共振研究。首先，尽管伴侣蛋白的三维结构存在根本差异，但大肠杆菌外膜蛋白OmpX以结构上至少部分相似的状态与两种伴侣蛋白Skp和SurA结合。其次，我们表明，就OmpX在体外重折叠成去污剂胶束的能力而言，其与Skp结合的状态等同于化学变性状态。第三，我们使用氨基酸突变分析表明，OmpX与Skp的相互作用并不由OmpX的两个最疏水片段主导。
