Competition between Sec- and TAT-dependent protein translocation in Escherichia coli
Competition between Sec- and TAT-dependent protein translocation in Escherichia coli
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DOI：
10.1093/emboj/18.11.2982
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发表时间：
1999-06-01
期刊：
影响因子：
11.4
通讯作者：
von Heijne, G
中科院分区：
文献类型：
--
作者：
Cristóbal, S;de Gier, JW;von Heijne, G
近年来，在细菌和叶绿体中发现了一条新的蛋白质转运途径--双精氨酸转运（达特）途径。为了研究可能的竞争之间的达特-和良好的特点，在大肠杆菌中的Sec translocon依赖的途径，我们已经融合的TorA TAT靶向信号肽的Sec依赖的内膜蛋白前导肽酶（Lep）。我们发现Lep的可溶性周质P2结构域被TorA信号肽重新路由到达特通路中，相反，全长TorA-Lep融合蛋白没有重新路由到达特通路中，这表明Lep中的Sec靶向信号可以覆盖TorA信号肽中的TAT靶向信息。我们还表明，TorA信号肽可以通过增加其h-区的疏水性转化为Sec-靶向信号肽。因此，除了双精氨酸基序之外，信号肽的总体疏水性在达特与Sec靶向中起重要作用。这与统计数据一致，该统计数据显示TAT-靶向信号肽通常具有比Sec-靶向信号肽更少的疏水性h-区。
Recently, a new protein translocation pathway, the twin-arginine translocation (TAT) pathway, has been identified in both bacteria and chloroplasts. To study the possible competition between the TAT- and the well-characterized Sec translocon-dependent pathways in Escherichia coli, we have fused the TorA TAT-targeting signal peptide to the Sec-dependent inner membrane protein leader peptidase (Lep). We find that the soluble, periplasmic P2 domain from Lep is re-routed by the TorA signal peptide into the TAT pathway, In contrast, the full-length TorA-Lep fusion protein is not re-routed into the TAT pathway, suggesting that Sec-targeting signals in Lep can override TAT-targeting information in the TorA signal peptide. We also show that the TorA signal peptide can be converted into a Sec-targeting signal peptide by increasing the hydrophobicity of its h-region, Thus, beyond the twin-arginine motif, the overall hydrophobicity of the signal peptide plays an important role in TAT versus Sec targeting, This is consistent with statistical data showing that TAT-targeting signal peptides in general have less hydrophobic h-regions than Sec-targeting signal peptides.