title: Identification and characterization of a bacitracin resistance network in Enterococcus faecalis.
abstract: Resistance of Enterococcus faecalis against antimicrobial peptides, both of host origin and produced by other bacteria of the gut microflora, is likely to be an important factor in the bacterium's success as an intestinal commensal. The aim of this study was to identify proteins with a role in resistance against the model antimicrobial peptide bacitracin. Proteome analysis of bacitracin-treated and untreated cells showed that bacitracin stress induced the expression of cell wall-biosynthetic proteins and caused metabolic rearrangements. Among the proteins with increased production, an ATP-binding cassette (ABC) transporter with similarity to known peptide antibiotic resistance systems was identified and shown to mediate resistance against bacitracin. Expression of the transporter was dependent on a two-component regulatory system and a second ABC transporter, which were identified by genome analysis. Both resistance and the regulatory pathway could be functionally transferred to Bacillus subtilis, proving the function and sufficiency of these components for bacitracin resistance. Our data therefore show that the two ABC transporters and the two-component system form a resistance network against antimicrobial peptides in E. faecalis, where one transporter acts as the sensor that activates the TCS to induce production of the second transporter, which mediates the actual resistance.
authors.affiliation: Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Martinsried, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Gebhard
authors.forename: Chong
authors.initials: C
authors.lastname: Fang
authors.forename: Aishath
authors.initials: A
authors.lastname: Shaaly
authors.forename: David J
authors.initials: DJ
authors.lastname: Leslie
authors.forename: Marion R
authors.initials: MR
authors.lastname: Weimar
authors.forename: Falk
authors.initials: F
authors.lastname: Kalamorz
authors.forename: Alan
authors.initials: A
authors.lastname: Carne
authors.forename: Gregory M
authors.initials: GM
authors.lastname: Cook
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000502:physiology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001414:Bacitracin / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D013293:Enterococcus faecalis / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D015964:Gene Expression Regulation, Bacterial; D008826:Microbial Sensitivity Tests; D011401:Promoter Regions, Genetic / Q000235:genetics; D020543:Proteome
chemical_list: D018528:ATP-Binding Cassette Transporters; D000900:Anti-Bacterial Agents; D020543:Proteome; D001414:Bacitracin