Biozentrum, University of Basel, Basel, Switzerland.
Nat Struct Mol Biol. 2013 Nov;20(11):1265-72. doi: 10.1038/nsmb.2677. Epub 2013 Sep 29.
The biogenesis of integral outer-membrane proteins (OMPs) in Gram-negative bacteria requires molecular chaperones that prevent the aggregation of OMP polypeptides in the aqueous periplasmic space. How these energy-independent chaperones interact with their substrates is not well understood. We have used high-resolution NMR spectroscopy to examine the conformation and dynamics of the Escherichia coli periplasmic chaperone Skp and two of its complexes with OMPs. The Skp trimer constitutes a flexible architectural scaffold that becomes more rigid upon substrate binding. The OMP substrates populate a dynamic conformational ensemble with structural interconversion rates on the submillisecond timescale. The global lifetime of the chaperone-substrate complex is seven orders of magnitude longer, emerging from the short local lifetimes by avidity. The dynamic state allows for energy-independent substrate release and provides a general paradigm for the conformation of OMP polypeptides bound to energy-independent chaperones.
革兰氏阴性细菌中完整外膜蛋白（OMP）的生物发生需要分子伴侣，以防止 OMP 多肽在水性周质空间中聚集。这些不依赖能量的伴侣如何与其底物相互作用还不是很清楚。我们使用高分辨率 NMR 光谱技术研究了大肠杆菌周质伴侣 Skp 及其与两种 OMP 复合物的构象和动态。Skp 三聚体构成了一个灵活的结构支架，在底物结合后变得更加刚性。OMP 底物在亚毫秒时间尺度上具有结构互变率的动态构象 ensemble。伴侣-底物复合物的整体寿命长七个数量级，通过亲合力从短的局部寿命中出现。这种动态状态允许不依赖能量的底物释放，并为与不依赖能量的伴侣结合的 OMP 多肽的构象提供了一个通用范例。
