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A novel Sec-independent periplasmic protein translocation pathway in Escherichia coli
被引:283
作者:
Santini, CL
Ize, B
Chanal, A
Müller, M
Giordano, G
Wu, LF
机构:
[1] Inst Biol Struct & Microbiol, UPR 9043 CNRS, Chim Bacterienne Lab, F-13402 Marseille 20, France
[2] Univ Freiburg, Inst Biochem & Mol Biol, D-79104 Freiburg, Germany
关键词:
metalloenzyme;
periplasm;
Sec system;
signal recognition particle;
twin-arginine motif;
D O I:
10.1093/emboj/17.1.101
中图分类号:
Q5 [生物化学];
Q7 [分子生物学];
学科分类号:
071010 ;
081704 ;
摘要:
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.
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页码:101 / 112
页数:12
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