Influence of tat mutations on the ribose-binding protein translocation in Escherichia coli.
Proteins are exported across the bacterial cytoplasmic membrane either as unfolded precursors via the Sec machinery or in folded conformation via the Tat system. The ribose-binding protein (RBP) of Escherichia coli is a Sec-pathway substrate. Intriguingly, it exhibits fast folding kinetics and its export is independent of SecB, a general chaperone protein dedicated for protein secretion. In this study, we found that the quantity of RBP was significantly reduced in the periplasm of tat mutants, which was restored by in trans expression of the tatABC genes. Pulse-chase experiments showed that significant amount of wild-type RBP was processed in a secY mutant in the presence of azide (SecA inhibitor), whereas the processing of a slow folding RBP derivative was almost completely blocked under the same conditions. These results would suggest that under the Sec-defective conditions the export of a portion of folded RBP could be rescued by the Tat system.
Pradel
Nathalie
N
Laboratoire de Chimie Bactérienne, UPR9043, Institut de Biologie Structurale et Microbiologie, CNRS, 31 chemin Joseph Aiguier, F-13402 20, Marseille cedex, France.
Santini
Claire-Lise
CL
Ye
Chang-Yun
CY
Fevat
Léna
L
Gérard
Fabien
F
Alami
Meriem
M
Wu
Long-Fei
LF
D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D033902:Periplasmic Binding Proteins / Q000378:metabolism*; D017510:Protein Folding; D021381:Protein Transport / Q000502:physiology*; D000069816:SEC Translocation Channels; D000081416:SecA Proteins
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D033902:Periplasmic Binding Proteins; C028003:RbsB protein, E coli; D000069816:SEC Translocation Channels; C408585:twin-arginine translocase complex, E coli; D000251:Adenosine Triphosphatases; D000081416:SecA Proteins