A novel Sec-independent periplasmic protein translocation pathway in Escherichia coli
A novel Sec-independent periplasmic protein translocation pathway in Escherichia coli
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DOI：
10.1093/emboj/17.1.101
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发表时间：
1998-01-02
期刊：
影响因子：
11.4
通讯作者：
Wu, LF
中科院分区：
文献类型：
--
作者：
Santini, CL;Ize, B;Wu, LF
大肠杆菌的三甲胺N-氧化物(TMAO)还原酶是一种可溶性周质钼酶，该酶的前体具有可裂解的N端信号序列，其中含有双精氨酸蛾，通过使用在钼辅因子生物合成的不同步骤中存在缺陷的各种moa、mob和mod突变体，我们证明在细胞质中获得钼辅因子是钼辅因子易位的先决条件。 TMAO还原酶，TMAO还原酶前体的激活和易位是翻译后过程，并且激活与易位是可解离的，TMAO还原酶的输出主要由质子动力驱动，而叠氮化钠对输出的影响有限。最有趣的观察是TMAO还原酶穿过细胞质膜的易位与SecY、SecE、SecA和SecB 蛋白。 Ffh（大肠杆菌信号识别颗粒的核心成分）的耗尽似乎对 TMAO 还原酶的输出有轻微影响。这些结果强烈表明，钼酶 TMAO 还原酶易位到周质中使用的机制与一般蛋白质易位根本不同。
The trimethylamine N-oxide (TMAO) reductase of Escherichia coli is a soluble periplasmic molybdoenzyme, The precursor of this enzyme possesses a cleavable N-terminal signal sequence which contains a twin-arginine moth, By using various moa, mob and mod mutants defective in different steps of molybdocofactor biosynthesis, we demonstrate that acquisition of the molybdocofactor in the cytoplasm is a prerequisite for the translocation of the TMAO reductase, The activation and translocation of the TMAO reductase precursor are post-translational processes, and activation is dissociable from translocation, The export of the TMAO reductase is driven mainly by the proton motive force, whereas sodium azide exhibits a limited effect on the export, The most intriguing observation is that translocation of the TMAO reductase across the cytoplasmic membrane is independent of the SecY, SecE, SecA and SecB proteins. Depletion of Ffh, a core component of the signal recognition particle of E. coli, appears to have a slight effect on the export of the TMAO reductase, These results strongly suggest that the translocation of the molybdoenzyme TMAO reductase into the periplasm uses a mechanism fundamentally different from general protein translocation.