A subset of bacterial inner membrane proteins integrated by the twin-arginine translocase
A subset of bacterial inner membrane proteins integrated by the twin-arginine translocase
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DOI：
10.1046/j.1365-2958.2003.03642.x
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发表时间：
2003-09-01
影响因子：
3.6
通讯作者：
Sargent, F
中科院分区：
文献类型：
--
作者：
Hatzixanthis, K;Palmer, T;Sargent, F
一组细菌输出的蛋白质是用含有SRRxFLK“双精氨酸”氨基酸基序的N-末端信号肽合成的。携带双精氨酸信号肽的蛋白质在转录后被靶向双精氨酸易位（达特）系统，该系统将折叠的底物转运穿过内膜。在大肠杆菌中，大多数完整的内膜蛋白通过SRP/FtsY、SecYEG移位酶和YidC指导的共翻译过程组装。在这项工作中，我们定义了一类新的完整的膜蛋白组装的Tat依赖的机制。我们发现，至少有五个E。大肠杆菌达特底物蛋白含有疏水C-末端跨膜螺旋（或“C-尾”）。所鉴定的跨膜C-尾和专门Tat依赖性报告蛋白TorA和SufI之间的融合使得所得嵌合体膜结合。嵌合体的输出连接的信号肽加工和膜整合被证明是Tat依赖性和YidC独立性的。有人提出，达特系统的蛋白质膜整合机制与
A group of bacterial exported proteins are synthesized with N-terminal signal peptides containing a SRRxFLK 'twin-arginine' amino acid motif. Proteins bearing twin-arginine signal peptides are targeted post-translationally to the twin-arginine translocation (Tat) system which transports folded substrates across the inner membrane. In Escherichia coli, most integral inner membrane proteins are assembled by a co-translational process directed by SRP/FtsY, the SecYEG translocase, and YidC. In this work we define a novel class of integral membrane proteins assembled by a Tat-dependent mechanism. We show that at least five E. coli Tat substrate proteins contain hydrophobic C-terminal transmembrane helices (or 'C-tails'). Fusions between the identified transmembrane C-tails and the exclusively Tat-dependent reporter proteins TorA and SufI render the resultant chimeras membrane-bound. Export-linked signal peptide processing and membrane integration of the chimeras is shown to be both Tat-dependent and YidC-independent. It is proposed that the mechanism of membrane integration of proteins by the Tat system is fundamentally distinct from