Solution NMR mapping of water-accessible residues in the transmembrane β-barrel of OmpX
Solution NMR mapping of water-accessible residues in the transmembrane β-barrel of OmpX
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DOI：
10.1007/s00249-009-0513-2
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发表时间：
2010-03-01
影响因子：
2
通讯作者：
Popot, Jean-Luc
中科院分区：
文献类型：
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作者：
Catoire, Laurent J.;Zoonens, Manuela;Popot, Jean-Luc
OmpX 是细菌外膜蛋白家族最小的成员，其原子结构先前已通过 X 射线晶体学和核磁共振波谱法确定。与电生理学研究明显冲突的是，其跨膜β-桶的内腔似乎与氨基酸侧链堆积得太紧密，无法让任何溶质流过。在本研究中，通过 amphipol A8-35 或洗涤剂二己酰磷脂酰胆碱保持水溶性的 OmpX 获得了高分辨率溶液 NMR 谱。长时间平衡后进行的氢/氘交换测量表明，无论使用何种表面活性剂，跨膜区域的一些酰胺质子比其他酰胺质子更容易交换，这可能反映了桶的动力学。
The atomic structure of OmpX, the smallest member of the bacterial outer membrane protein family, has been previously established by X-ray crystallography and NMR spectroscopy. In apparent conflict with electrophysiological studies, the lumen of its transmembrane beta-barrel appears too tightly packed with amino acid side chains to let any solute flow through. In the present study, high-resolution solution NMR spectra were obtained of OmpX kept water-soluble by either amphipol A8-35 or the detergent dihexanoylphosphatidylcholine. Hydrogen/deuterium exchange measurements performed after prolonged equilibration show that, whatever the surfactant used, some of the amide protons of the membrane-spanning region exchange much more readily than others, which likely reflects the dynamics of the barrel.