title: A sensory complex consisting of an ATP-binding cassette transporter and a two-component regulatory system controls bacitracin resistance in Bacillus subtilis.
abstract: Resistance against antimicrobial peptides in many Firmicutes bacteria is mediated by detoxification systems that are composed of a two-component regulatory system (TCS) and an ATP-binding cassette (ABC) transporter. The histidine kinases of these systems depend entirely on the transporter for sensing of antimicrobial peptides, suggesting a novel mode of signal transduction where the transporter constitutes the actual sensor. The aim of this study was to investigate the molecular mechanisms of this unusual signaling pathway in more detail, using the bacitracin resistance system BceRS-BceAB of Bacillus subtilis as an example. To analyze the proposed communication between TCS and the ABC transporter, we characterized their interactions by bacterial two-hybrid analyses and could show that the permease BceB and the histidine kinase BceS interact directly. In vitro pulldown assays confirmed this interaction, which was found to be independent of bacitracin. Because it was unknown whether BceAB-type transporters could detect their substrate peptides directly or instead recognized the peptide-target complex in the cell envelope, we next analyzed substrate binding by the transport permease, BceB. Direct and specific binding of bacitracin by BceB was demonstrated by surface plasmon resonance spectroscopy. Finally, in vitro signal transduction assays indicated that complex formation with the transporter influenced the autophosphorylation activity of the histidine kinase. Taken together, our findings clearly show the existence of a sensory complex composed of TCS and ABC transporters and provide the first functional insights into the mechanisms of stimulus perception, signal transduction, and antimicrobial resistance employed by Bce-like detoxification systems.
authors.affiliation: From the Department of Biology I, Microbiology, and.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Dintner
authors.affiliation: From the Department of Biology I, Microbiology, and.
authors.forename: Ralf
authors.initials: R
authors.lastname: Heermann
authors.affiliation: From the Department of Biology I, Microbiology, and.
authors.forename: Chong
authors.initials: C
authors.lastname: Fang
authors.affiliation: From the Department of Biology I, Microbiology, and Munich Center for Integrated Protein Science, Ludwig-Maximilians-Universität München, 82152 Martinsried, Germany.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Jung
authors.affiliation: From the Department of Biology I, Microbiology, and susanne.gebhard@gmail.com.
authors.forename: Susanne
authors.initials: S
authors.lastname: Gebhard
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D000900:Anti-Bacterial Agents / Q000378:metabolism* / Q000494:pharmacology; D001412:Bacillus subtilis / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D001414:Bacitracin / Q000378:metabolism* / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D024881:Drug Resistance, Bacterial; D000071677:Histidine Kinase; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*
chemical_list: D018528:ATP-Binding Cassette Transporters; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D026901:Membrane Transport Proteins; D001414:Bacitracin; D011494:Protein Kinases; D000071677:Histidine Kinase
keywords: ABC Transporter; Antimicrobial Peptide (AMP); Bacitracin; Histidine Kinase; Membrane Protein; Protein-Protein Interaction