Membrane Curvature Affects the Formation of a-Hemolysin Nanopores
Membrane Curvature Affects the Formation of a-Hemolysin Nanopores
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DOI：
10.1021/acschembio.5b00107
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发表时间：
2015-07-01
影响因子：
4
通讯作者：
Yomo, Tetsuya
中科院分区：
文献类型：
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作者：
Fujii, Satoshi;Matsuura, Tornoald;Yomo, Tetsuya
膜蛋白在脂质膜内或在脂质膜上执行其功能，并且已知脂质组合物影响膜蛋白整合和活性。最近，膜曲率的几何方面被证明在膜蛋白的行为中起着重要的作用。已知某些膜蛋白能够感知膜的曲率，并优先与高度弯曲的膜结合。然而，尽管许多膜蛋白组装形成同源或杂合物并执行其生物学功能，膜蛋白组装对膜曲率的依赖性仍然难以捉摸。在这项研究中，我们分析了膜曲率对α-溶血素（AH）纳米孔形成的影响，α-溶血素是一种来源于金黄色葡萄球菌的毒性膜蛋白。AH蛋白作为单体与膜结合，组装形成七聚体，并形成纳米孔。通过同时测量结合到膜上的分子和膜上纳米孔的活性，我们确定了AH的纳米孔形成率。我们使用了不同大小的脂质体，并通过使用流式细胞术分析了对膜曲率的依赖性。结合正曲率和负曲率的结果，我们发现AH的纳米孔形成率是曲率敏感的，并且在平坦膜中比在弯曲膜中更高。此外，纳米孔形成率是几乎相同的或相对较高的膜与负曲率比那些具有正曲率。
Membrane proteins perform their functions within or on the lipid membrane, and lipid compositions are known to affect membrane protein integration and activity. Recently, the geometric aspect of membrane curvature was shown to play an important role in membrane protein behavior. Certain membrane proteins are known to sense the curvature of the membrane and to preferentially bind to highly curved membranes. However, although numerous membrane proteins assemble to form homo- or heterocomplexes and perform their biological functions, the dependence of membrane protein assembly on membrane curvature remains elusive. In this study, we analyzed the effect of the membrane curvature on the nanopore formation of a-hemolysin (AH), which is a toxic membrane protein derived from Staphylococcus aureus. The AH protein binds to the membrane as a monomer, assembles to form a heptamer, and forms a nanopore. By simultaneously measuring the molecules bound to the membrane and the activities of the nanopore on the membrane, we determined the nanopore formation ratio of AH. We used various sizes of liposomes and analyzed the dependence on the membrane curvature by using flow cytometry. Combining the results for positive and negative curvature, we found that the nanopore formation ratio of AH was curvature sensitive and was higher in a flat membrane than in a curved membrane. Furthermore, the nanopore formation ratio was almost identical or relatively higher in membranes with negative curvature than those with positive curvature.