title: Identification of regions important for resistance and signalling within the antimicrobial peptide transporter BceAB of Bacillus subtilis.
abstract: In the low-G+C-content Gram-positive bacteria, resistance to antimicrobial peptides is often mediated by so-called resistance modules. These consist of a two-component system and an ATP-binding cassette transporter and are characterized by an unusual mode of signal transduction where the transporter acts as a sensor of antimicrobial peptides, because the histidine kinase alone cannot detect the substrates directly. Thus, the transporters fulfill a dual function as sensors and detoxification systems to confer resistance, but the mechanistic details of these processes are unknown. The paradigm and best-understood example for this is the BceRS-BceAB module of Bacillus subtilis, which mediates resistance to bacitracin, mersacidin, and actagardine. Using a random mutagenesis approach, we here show that mutations that affect specific functions of the transporter BceAB are primarily found in the C-terminal region of the permease, BceB, particularly in the eighth transmembrane helix. Further, we show that while signaling and resistance are functionally interconnected, several mutations could be identified that strongly affected one activity of the transporter but had only minor effects on the other. Thus, a partial genetic separation of the two properties could be achieved by single amino acid replacements, providing first insights into the signaling mechanism of these unusual modules.
authors.affiliation: Ludwig-Maximilians-Universität München, Department Biology I, Microbiology, Martinsried, Germany.
authors.forename: Felix
authors.initials: F
authors.lastname: Kallenberg
authors.forename: Sebastian
authors.initials: S
authors.lastname: Dintner
authors.forename: Roland
authors.initials: R
authors.lastname: Schmitz
authors.forename: Susanne
authors.initials: S
authors.lastname: Gebhard
mesh_terms: D000900:Anti-Bacterial Agents / Q000378:metabolism*; D023181:Antimicrobial Cationic Peptides / Q000378:metabolism*; D001412:Bacillus subtilis / Q000235:genetics / Q000378:metabolism*; D001414:Bacitracin / Q000378:metabolism; D001430:Bacteriocins / Q000378:metabolism; D001693:Biological Transport, Active; D004252:DNA Mutational Analysis; D024881:Drug Resistance, Bacterial; D015964:Gene Expression Regulation, Bacterial; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D016296:Mutagenesis; D010455:Peptides / Q000378:metabolism; D021381:Protein Transport; D015398:Signal Transduction
chemical_list: D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D001430:Bacteriocins; D026901:Membrane Transport Proteins; D010455:Peptides; C069959:mersacidin; D001414:Bacitracin; C012993:gardimycin