Lipid-protein interactions as determinants of membrane protein structure and function.
Lipid-protein interactions as determinants of membrane protein structure and function.
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DOI：
10.1042/bst0390767
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发表时间：
2011-06
影响因子：
3.9
通讯作者：
Bogdanov M
中科院分区：
文献类型：
--
作者：
Dowhan W;Bogdanov M
为了确定脂质环境如何影响膜蛋白的结构和功能，培养出了可以改变正常磷脂组成或可以引入外源脂类的大肠杆菌菌株。研究了乳糖渗透酶(Lacy)的性质与脂质环境的关系。在缺乏PE(磷脂酰乙醇胺)的膜中组装Lacy导致N-末端6-TM(跨膜区)螺旋束方向错误，失去了能量依赖的上行运输和保留了能量无关的下行运输。装配后PE的引入导致TMS的近乎自然定向和上行运输的恢复。没有净电荷的外来脂质可以替代PE支持天然的Lacy拓扑结构，但上行运输的恢复依赖于天然拓扑结构和暴露于溶剂的结构域的正确折叠。在没有中性脂类的情况下，增加花边计数器细胞质暴露表面的正电荷密度使TM取向错误，表明这些结构域与膜双层表面之间的电荷相互作用是TM取向的决定因素。因此，膜蛋白的组织或重组是在初始组装过程中或插入后通过蛋白质与脂环境之间的直接相互作用来确定的，这影响了相反带电残基作为不依赖于转位子的拓扑信号的拓扑发生能力。
To determine how the lipid environment affects membrane protein structure and function, strains of Escherichia coli were developed in which normal phospholipid composition can be altered or foreign lipids can be introduced. The properties of LacY (lactose permease) were investigated as a function of lipid environment. Assembly of LacY in membranes lacking PE (phosphatidylethanolamine) results in misorientation of the N-terminal six-TM (transmembrane domain) helical bundle with loss of energy-dependent uphill transport and retention of energy-independent downhill transport. Post-assembly introduction of PE results in nearly native orientation of TMs and restoration of uphill transport. Foreign lipids with no net charge can substitute for PE in supporting native LacY topology, but restoration of uphill transport is dependent on native topology and the proper folding of a solvent-exposed domain. Increasing the positive charge density of the cytoplasmically exposed surface of LacY counters TM misorientation in the absence of neutral lipids, demonstrating that charge interactions between these domains and the surface of the membrane bilayer are determinants of TM orientation. Therefore membrane protein organization or reorganization is determined either during initial assembly or post-insertionally through direct interactions between the protein and the lipid environment, which affects the topogenic potency of opposing charged residues as topological signals independent of the translocon.