The twin-arginine translocation pathway is a major route of protein export in Streptomyces coelicolor

Abstract

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-⌽-⌽ ''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 polymerdegrading 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.Protein transport ͉ secondary metabolism ͉ Tat pathway ͉ twin arginine signal peptide ͉ proteome

A novel phospholipase B from Streptomyces sp. NA684 – purification, characterization, gene cloning, extracellular production and prediction of the catalytic residues

“…The signal peptide sequence of PLB 684 is composed of 30 amino acid residues prior to the N-terminus, as determined by the protein sequencer. PLB 684 should be secreted via the secretory pathway (Sec-system secretion) because the signal peptide sequence of PLB 684 includes no R-R-x-φ-φ 'twin-arginine' amino acid motif that represents a distinct motif of secreting proteins via the translocation pathway [47,48]. The transcription start sites of many Streptomyces genes have been defined [49,50].…”

Phosphate control of phoA, phoC and phoD gene expression in Streptomyces coelicolor reveals significant differences in binding of PhoP to their promoter regions

“…Their N-terminal regions contain the conserved twin-arginine motif defined as R-R-X-W-W, where W represents a hydrophobic amino acid (Berks, 1996). Using the TatP algorithm (Bendtsen et al, 2005) for prediction of proteins exported via the Tat pathway we identified a clear Tat motif in PhoC, with the sequence GAAARHLGRRRFLTVTAA (amino acids 23-40), nearly identical to the Tat motif RAAARSLGRRRFLTVTGA (amino acids 27-44) predicted for PhoA (Widdick et al, 2006), suggesting that PhoC might be secreted via the Tat pathway.…”

“…PhoA (SCO2286) and PhoD (SCO2068) were shown to be secreted via the twin arginine translocation (Tat) pathway, a major route for protein secretion in Streptomyces, (Widdick et al, 2006). Their N-terminal regions contain the conserved twin-arginine motif defined as R-R-X-W-W, where W represents a hydrophobic amino acid (Berks, 1996).…”

Lipoprotein biogenesis in Gram-positive bacteria: knowing when to hold ‘em, knowing when to fold ‘em

“…In the high Guanine+Cytosine branch of Gram-positive bacteria known as actinomycetes, Tat is also apparently required for the translocation of lipoproteins, including the BlaC b-lactamase putative lipoprotein of Mycobacterium tuberculosis when it is expressed in M. smegmatis [16] and four putative lipoproteins in the model actinomycete, Streptomyces coelicolor [17]. Bioinformatic analysis indicates that Tat translocation of lipoproteins is widespread in the genus Streptomyces with up to 20% of putative lipoproteins being exported via Tat in the four currently sequenced Streptomyces species (M.I.H and I.C.S, unpublished).…”