Membrane protein dynamics in different environments: simulation study of the outer membrane protein X in a lipid bilayer and in a micelle
Membrane protein dynamics in different environments: simulation study of the outer membrane protein X in a lipid bilayer and in a micelle
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DOI：
10.1007/s00249-010-0626-7
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发表时间：
2011-01-01
影响因子：
2
通讯作者：
van Gunsteren, Wilfred F.
中科院分区：
文献类型：
--
作者：
Choutko, Alexandra;Glaettli, Alice;van Gunsteren, Wilfred F.
来自大肠杆菌的细菌外膜蛋白 OmpX 嵌入磷脂双层并作为蛋白质胶束聚集体时，已通过分子动力学模拟进行了研究。根据膜蛋白的结构和动态特性分析了所得的模拟轨迹。与实验观察结果一致，嵌入亲脂相的β-桶区具有最高的相对稳定性，而细胞外突出的β-片层（OmpX 的独特结构特征，据称在细胞粘附和侵袭中发挥重要作用）显示出较大的结构波动。此外，我们还研究了水渗透到β-桶蛋白核心的情况，该蛋白包含紧密的盐桥和氢键网络，因此不太可能出现大量的水通量。双层和胶束系统之间的差异在于桶的长度及其在脂质环境内的位置，以及蛋白质与脂质/水界面附近脂质的亲水部分的相互作用。这些变化表明胶束和其他去污剂环境可能无法提供完全类似膜的环境来促进 OmpX 采用生理构象状态。
The bacterial outer membrane protein OmpX from Escherichia coli has been investigated by molecular dynamics simulations when embedded in a phospholipid bilayer and as a protein-micelle aggregate. The resulting simulation trajectories were analysed in terms of structural and dynamic properties of the membrane protein. In agreement with experimental observations, highest relative stability was found for the beta-barrel region that is embedded in the lipophilic phase, whereas an extracellular protruding beta-sheet, which is a unique structural feature of OmpX that supposedly plays an important role in cell adhesion and invasion, shows larger structure fluctuations. Additionally, we investigated water permeation into the core of the beta-barrel protein, which contains a tight salt-bridge and hydrogen-bond network, so that extensive water flux is unlikely. Differences between the bilayer and the micellar system were observed in the length of the barrel and its position inside the lipid environment, and in the protein interactions with the hydrophilic part of the lipids near the lipid/water interface. Those variations suggest that micelles and other detergent environments might not offer a wholly membrane-like milieu to promote adoption of the physiological conformational state by OmpX.