Membrane topology and multimeric structure of a mechanosensitive channel protein of Escherichia coli
Membrane topology and multimeric structure of a mechanosensitive channel protein of Escherichia coli
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DOI：
10.1002/j.1460-2075.1996.tb00860.x
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发表时间：
1996-09-16
期刊：
影响因子：
11.4
通讯作者：
Kung, C
中科院分区：
文献类型：
--
作者：
Blount, P;Sukharev, SI;Kung, C
我们已经研究了膜拓扑结构和多聚体结构的机械敏感通道，MscL，我们以前分离和克隆大肠杆菌。我们已经将该15-kDa蛋白定位于内膜，并且通过PhoA融合，已经表明它含有两个跨膜结构域，其氨基和羧基末端均位于细胞质侧。56位的谷氨酸突变为组氨酸导致通道动力学的变化，其依赖于膜的周质侧而不是细胞质侧的pH，两个MscL亚基串联表达为单一多肽，形成功能通道，这为分子的这一部分的周质定位提供了额外的证据，表明每个亚基的跨膜结构域的数量为偶数（氨基和羧基末端在膜的同一侧），和偶数个亚基每个功能复合物，最后，交联研究表明，功能MscL复合物是一个同源六聚体。总之，这些数据都与我们提出并讨论的蛋白质结构域分配和拓扑模型一致。
We have studied the membrane topology and multimeric structure of a mechanosensitive channel, MscL, which we previously isolated and cloned from Escherichia coli. We have localized this 15-kDa protein to the inner membrane and, by PhoA fusion, have shown that it contains two transmembrane domains with both the amino and carboxyl termini on the cytoplasmic side, Mutation of the glutamate at position 56 to histidine led to changes in channel kinetics which were dependent upon the pH on the periplasmic, but not cytoplasmic side of the membrane, providing additional evidence for the periplasmic positioning of this part of the molecule, Tandems of two MscL subunits expressed as a single polypeptide formed functional channels, suggesting an even number of transmembrane domains per subunit (amino and carboxyl termini on the same side of the membrane), and an even number of subunits per functional complex, Finally, cross-linking studies suggest that the functional MscL complex is a homo-hexamer. In summary, these data are all consistent with a protein domain assignment and topological model which we propose and discuss.