The mechanosensitive channel protein MscL is targeted by the SRP to the novel YidC membrane insertion pathway of Escherichia coli
The mechanosensitive channel protein MscL is targeted by the SRP to the novel YidC membrane insertion pathway of Escherichia coli
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DOI：
10.1016/j.jmb.2006.10.083
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发表时间：
2007-01-26
影响因子：
5.6
通讯作者：
Kuhn, Andreas
中科院分区：
文献类型：
--
作者：
Facey, Sandra J.;Neugebauer, Stella A.;Kuhn, Andreas
大肠杆菌内膜中的机械敏感通道MscL是当细胞暴露于低渗条件时参与稳态的同源五聚体复合物。急诊coli MscL，蛋白被合成为136个氨基酸残基的多肽，并使用细菌信号识别颗粒（SRP）进行膜靶向。蛋白质独立于Sec易位子插入膜中。Sec-组分中受影响的突变体能够进行MscL组装。易位的周质域检测使用膜不渗透，巯基特异性凝胶移位试剂。在位置68处的单个半胱氨酸残基的修饰指示其跨内膜的易位。从这些在体实验中，可以得出结论，电化学膜电位是不必要的MscL的膜插入。然而，膜插入酶YidC的耗竭抑制蛋白质跨膜的易位。我们在这里表明，YidC是必要的MscL蛋白的有效膜插入。YidC是最近鉴定的在细菌、线粒体和叶绿体中进化保守的膜插入途径的组分。(c)2006爱思唯尔有限公司保留所有权利。
The mechanosensitive channel MscL in the inner membrane of Escherichia coli is a homopentameric complex involved in homeostasis when cells are exposed to hypo-osmotic conditions. The E. coli MscL, protein is synthesized as a polypeptide of 136 amino acid residues and uses the bacterial signal recognition particle (SRP) for membrane targeting. The protein is inserted into the membrane independently of the Sec translocon. Mutants affected in the Sec-components are competent for MscL assembly. Translocation of the periplasmic domain was detected using a membrane-impermeant, sulfhydryl-specific gel-shift reagent. The modification of a single cysteine residue at position 68 indicated its translocation across the inner membrane. From these in vivo experiments, it is concluded that the electrical chemical membrane potential is not necessary for membrane insertion of MscL. However, depletion of the membrane insertase YidC inhibits translocation of the protein across the membrane. We show here that YidC is essential for efficient membrane insertion of the MscL protein. YidC is a component of a recently identified membrane insertion pathway that is evolutionarily conserved in bacteria, mitochondria and chloroplasts. (c) 2006 Elsevier Ltd. All rights reserved.