Escherichia coli tatC mutations that suppress defective twin-arginine transporter signal peptides.
Escherichia coli tatC mutations that suppress defective twin-arginine transporter signal peptides.
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DOI：
10.1016/j.jmb.2007.09.050
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发表时间：
2007-11
影响因子：
5.6
通讯作者：
Eva-Maria Strauch;G. Georgiou
中科院分区：
文献类型：
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作者：
Eva-Maria Strauch;G. Georgiou
体外研究表明，TatBC复合物作为信号肽的受体，通过双精氨酸易位（Tat）途径输出。用两种赖氨酸替代标志性的双精氨酸二肽，消除了所有生物体中生理底物的输出。我们报道了抑制突变的分离和特性，这些突变允许输出ssTor(KK)-GFP-SsrA三方融合。我们在TatC的第一个细胞质环中发现了两个氨基酸抑制突变。此外，第一个细胞质环中的另外两个氨基酸表现出上位性抑制。令人惊讶的是，我们还发现了一个抑制突变，预计位于TatC的第二质周环内，该区域预计不会与信号肽直接相互作用。抑制基因突变允许天然大肠杆菌Tat底物三甲胺n-氧化物还原酶输出，其信号序列中有双赖氨酸替代。细胞质抑制突变导致SDS敏感性和部分丝化，表明原底物的Tat输出受损。
In vitro studies have suggested that the TatBC complex serves as the receptor for signal peptides targeted for export via the twin-arginine translocation (Tat) pathway. Substitution of the hallmark twin-arginine dipeptide with two lysines abrogates export of physiological substrates in all organisms. We report the isolation and characterization of suppressor mutations that allow export of an ssTor(KK)-GFP-SsrA tripartite fusion. We identified two amino acid suppressor mutations in the first cytoplasmic loop of TatC. In addition, two other amino acids in the first cytoplasmic loop exhibit epistatic suppression. Surprisingly, we also identified a suppressor mutation predicted to lie within the second periplasmic loop of TatC, a region that is not expected to interact directly with the signal peptide. The suppressor mutations allowed export of the native Esherichia coli Tat substrate trimethylamine N-oxide reductase with a twin-lysine substitution in its signal sequence. The cytoplasmic suppressor mutations conferred SDS sensitivity and partial filamentation, indicating that Tat export of authentic substrates was impaired.