title: Selective contribution of the twin-arginine translocation pathway to protein secretion in Bacillus subtilis.
abstract: The availability of the complete genome sequence of Bacillus subtilis has allowed the prediction of all exported proteins of this Gram-positive eubacterium. Recently, approximately 180 secretory and 114 lipoprotein signal peptides were predicted to direct protein export from the cytoplasm. Whereas most exported proteins appear to use the Sec pathway, 69 of these proteins could potentially use the Tat pathway, as their signal peptides contain RR- or KR-motifs. In the present studies, proteomic techniques were applied to verify how many extracellular B. subtilis proteins follow the Tat pathway. Strikingly, the extracellular accumulation of 13 proteins with potential RR/KR-signal peptides was Tat-independent, showing that their RR/KR-motifs are not recognized by the Tat machinery. In fact, only the phosphodiesterase PhoD was shown to be secreted in a strictly Tat-dependent manner. Sodium azide-inhibition of SecA strongly affected the extracellular appearance of de novo synthesized proteins, including the lipase LipA and two other proteins with predicted RR/KR-signal peptides. The SecA-dependent export of pre-LipA is particularly remarkable, because its RR-signal peptide conforms well to stringent criteria for the prediction of Tat-dependent export in Escherichia coli. Taken together, our observations show that the Tat pathway makes a highly selective contribution to the extracellular proteome of B. subtilis.
authors.affiliation: Department of Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, Kerklaan 30, 9751 NN Haren, The Netherlands.
authors.forename: Jan D H
authors.initials: JD
authors.lastname: Jongbloed
authors.forename: Haike
authors.initials: H
authors.lastname: Antelmann
authors.forename: Michael
authors.initials: M
authors.lastname: Hecker
authors.forename: Reindert
authors.initials: R
authors.lastname: Nijland
authors.forename: Sierd
authors.initials: S
authors.lastname: Bron
authors.forename: Ulla
authors.initials: U
authors.lastname: Airaksinen
authors.forename: Frens
authors.initials: F
authors.lastname: Pries
authors.forename: Wim J
authors.initials: WJ
authors.lastname: Quax
authors.forename: Jan Maarten
authors.initials: JM
authors.lastname: van Dijl
authors.forename: Peter G
authors.initials: PG
authors.lastname: Braun
mesh_terms: D000595:Amino Acid Sequence; D001120:Arginine / Q000378:metabolism*; D001412:Bacillus subtilis / Q000378:metabolism*; D015153:Blotting, Western; D002462:Cell Membrane / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004926:Escherichia coli / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D010455:Peptides / Q000737:chemistry; D010940:Plant Proteins / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D021382:Protein Sorting Signals; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D017386:Sequence Homology, Amino Acid; D019810:Sodium Azide / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D008565:Membrane Proteins; D010455:Peptides; D010940:Plant Proteins; D021382:Protein Sorting Signals; C432107:TatC protein, plant; D004247:DNA; D001120:Arginine; D019810:Sodium Azide