Truncation analysis of TatA and TatB defines the minimal functional units required for protein translocation
Truncation analysis of TatA and TatB defines the minimal functional units required for protein translocation
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DOI：
10.1128/jb.184.21.5871-5879.2002
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发表时间：
2002-11-01
影响因子：
3.2
通讯作者：
Palmer, T
中科院分区：
文献类型：
--
作者：
Lee, PA;Buchanan, G;Palmer, T
TatA和TatB蛋白是大肠杆菌中双精氨酸蛋白易位途径的重要组成部分。TatA蛋白的C-末端截短分析显示，缩短40个氨基酸的质粒表达的TatA蛋白仍然完全能够支持蛋白质易位。TatB的类似截短分析表明，TatB的最后30个残基是功能性的。用TatB进行的进一步缺失实验表明，从其C末端去除甚至70个残基仍然允许显著的运输。这些结果意味着TatA和TatB的跨膜和两亲性螺旋区域对于它们的功能是至关重要的，但是C-末端结构域对于达特转运活性不是必需的。包含与TatB的两亲性和C-末端结构域融合的TatA的N-末端区域的嵌合蛋白在其中缺失tatA或tatB（但不是两者）的野生型拷贝的菌株中支持低水平的达特活性。
The TatA and TatB proteins are essential components of the twin arginine protein translocation pathway in Escherichia coli. C-terminal truncation analysis of the TatA protein revealed that a plasmid-expressed TatA protein shortened by 40 amino acids is still fully competent to support protein translocation. Similar truncation analysis of TatB indicated that the final 30 residues of TatB are dispensable for function. Further deletion experiments with TatB indicated that removal of even 70 residues from its C terminus still allowed significant transport. These results imply that the transmembrane and amphipathic helical regions of TatA and TatB are critical for their function but that the C-terminal domains are not essential for Tat transport activity. A chimeric protein comprising the N-terminal region of TatA fused to the amphipathic and C-terminal domains of TatB supports a low level of Tat activity in a strain in which the wild-type copy of either tatA or tatB (but not both) is deleted.