The twin-arginine translocation pathway is a major route of protein export in Streptomyces coelicolor.
The twin-arginine translocation (Tat) pathway is a protein transport system for the export of folded proteins. Substrate proteins are targeted to the Tat translocase by N-terminal signal peptides harboring a distinctive R-R-x-Phi-Phi "twin-arginine" amino acid motif. Using a combination of proteomic techniques, the protein contents from the cell wall of the model Gram-positive bacterium Streptomyces coelicolor were identified and compared with that of mutant strains defective in Tat transport. The proteomic experiments pointed to 43 potentially Tat-dependent extracellular proteins. Of these, 25 were verified as bearing bona fide Tat-targeting signal peptides after independent screening with a facile, rapid, and sensitive reporter assay. The identified Tat substrates, among others, include polymer-degrading enzymes, phosphatases, and binding proteins as well as enzymes involved in secondary metabolism. Moreover, in addition to predicted extracellular substrates, putative lipoproteins were shown to be Tat-dependent. This work provides strong experimental evidence that the Tat system is used as a major general export pathway in Streptomyces.
Widdick
David A
DA
Department of Molecular Microbiology, John Innes Centre, Norwich NR4 7UH, United Kingdom.
Dilks
Kieran
K
Chandra
Govind
G
Bottrill
Andrew
A
Naldrett
Mike
M
Pohlschröder
Mechthild
M
Palmer
Tracy
T
D001120:Arginine / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins; D006026:Glycoside Hydrolases / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D021382:Protein Sorting Signals; D021381:Protein Transport / Q000502:physiology*; D040901:Proteomics / Q000379:methods; D048372:Streptomyces coelicolor / Q000166:cytology / Q000378:metabolism*
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D021382:Protein Sorting Signals; C408585:twin-arginine translocase complex, E coli; D001120:Arginine; D006026:Glycoside Hydrolases; C019624:agarase