title: The multidrug ABC transporter BmrC/BmrD of Bacillus subtilis is regulated via a ribosome-mediated transcriptional attenuation mechanism.
abstract: Expression of particular drug transporters in response to antibiotic pressure is a critical element in the development of bacterial multidrug resistance, and represents a serious concern for human health. To obtain a better understanding of underlying regulatory mechanisms, we have dissected the transcriptional activation of the ATP-binding cassette (ABC) transporter BmrC/BmrD of the Gram-positive model bacterium Bacillus subtilis. By using promoter-GFP fusions and live cell array technology, we demonstrate a temporally controlled transcriptional activation of the bmrCD genes in response to antibiotics that target protein synthesis. Intriguingly, bmrCD expression only occurs during the late-exponential and stationary growth stages, irrespective of the timing of the antibiotic challenge. We show that this is due to tight transcriptional control by the transition state regulator AbrB. Moreover, our results show that the bmrCD genes are co-transcribed with bmrB (yheJ), a small open reading frame immediately upstream of bmrC that harbors three alternative stem-loop structures. These stem-loops are apparently crucial for antibiotic-induced bmrCD transcription. Importantly, the antibiotic-induced bmrCD expression requires translation of bmrB, which implies that BmrB serves as a regulatory leader peptide. Altogether, we demonstrate for the first time that a ribosome-mediated transcriptional attenuation mechanism can control the expression of a multidrug ABC transporter.
authors.affiliation: Department of Medical Microbiology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, P.O. box 30001, 9700 RB Groningen, the Netherlands.
authors.forename: Ewoud
authors.initials: E
authors.lastname: Reilman
authors.affiliation: Department of Medical Microbiology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, P.O. box 30001, 9700 RB Groningen, the Netherlands.
authors.forename: Ruben A T
authors.initials: RA
authors.lastname: Mars
authors.affiliation: Department of Medical Microbiology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, P.O. box 30001, 9700 RB Groningen, the Netherlands J.M.van.Dijl@med.umcg.nl.
authors.forename: Jan Maarten
authors.initials: JM
authors.lastname: van Dijl
authors.affiliation: Department of Medical Microbiology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, P.O. box 30001, 9700 RB Groningen, the Netherlands.
authors.forename: Emma L
authors.initials: EL
authors.lastname: Denham
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics* / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001412:Bacillus subtilis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D003062:Codon; D004268:DNA-Binding Proteins / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D009876:Operon; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000378:metabolism; D012270:Ribosomes / Q000187:drug effects / Q000502:physiology*; D013728:Terminator Regions, Genetic; D014157:Transcription Factors / Q000378:metabolism; D061806:Transcription Termination, Genetic; D015533:Transcriptional Activation
chemical_list: D018528:ATP-Binding Cassette Transporters; C060762:AbrB protein, Bacillus subtilis; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D003062:Codon; D004268:DNA-Binding Proteins; D012097:Repressor Proteins; D014157:Transcription Factors