title: Environmental salinity determines the specificity and need for Tat-dependent secretion of the YwbN protein in Bacillus subtilis.
abstract: Twin-arginine protein translocation (Tat) pathways are required for transport of folded proteins across bacterial, archaeal and chloroplast membranes. Recent studies indicate that Tat has evolved into a mainstream pathway for protein secretion in certain halophilic archaea, which thrive in highly saline environments. Here, we investigated the effects of environmental salinity on Tat-dependent protein secretion by the Gram-positive soil bacterium Bacillus subtilis, which encounters widely differing salt concentrations in its natural habitats. The results show that environmental salinity determines the specificity and need for Tat-dependent secretion of the Dyp-type peroxidase YwbN in B. subtilis. Under high salinity growth conditions, at least three Tat translocase subunits, namely TatAd, TatAy and TatCy, are involved in the secretion of YwbN. Yet, a significant level of Tat-independent YwbN secretion is also observed under these conditions. When B. subtilis is grown in medium with 1% NaCl or without NaCl, the secretion of YwbN depends strictly on the previously described "minimal Tat translocase" consisting of the TatAy and TatCy subunits. Notably, in medium without NaCl, both tatAyCy and ywbN mutants display significantly reduced exponential growth rates and severe cell lysis. This is due to a critical role of secreted YwbN in the acquisition of iron under these conditions. Taken together, our findings show that environmental conditions, such as salinity, can determine the specificity and need for the secretion of a bacterial Tat substrate.
authors.affiliation: Department of Medical Microbiology, University Medical Center Groningen and University of Groningen, Groningen, The Netherlands.
authors.forename: René
authors.initials: R
authors.lastname: van der Ploeg
authors.forename: Ulrike
authors.initials: U
authors.lastname: Mäder
authors.forename: Georg
authors.initials: G
authors.lastname: Homuth
authors.forename: Marc
authors.initials: M
authors.lastname: Schaffer
authors.forename: Emma L
authors.initials: EL
authors.lastname: Denham
authors.forename: Carmine G
authors.initials: CG
authors.lastname: Monteferrante
authors.forename: Marcus
authors.initials: M
authors.lastname: Miethke
authors.forename: Mohamed A
authors.initials: MA
authors.lastname: Marahiel
authors.forename: Colin R
authors.initials: CR
authors.lastname: Harwood
authors.forename: Theresa
authors.initials: T
authors.lastname: Winter
authors.forename: Michael
authors.initials: M
authors.lastname: Hecker
authors.forename: Haike
authors.initials: H
authors.lastname: Antelmann
authors.forename: Jan Maarten
authors.initials: JM
authors.lastname: van Dijl
mesh_terms: D001412:Bacillus subtilis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015152:Blotting, Northern; D004777:Environment; D015964:Gene Expression Regulation, Bacterial; D005816:Genetic Complementation Test; D007501:Iron / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000378:metabolism*; D010641:Phenotype; D010957:Plasmids / Q000235:genetics; D054712:Salinity; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D026901:Membrane Transport Proteins; D007501:Iron