Expression of the AcrAB Components of the AcrAB-TolC Multidrug Efflux Pump of Yersinia enterocolitica Is Subject to Dual Regulation by OmpR

• Published in: PloS one Vol. 10; no. 4; p. e0124248
• Main Authors: Raczkowska, Adrianna, Trzos, Joanna, Lewandowska, Olga, Nieckarz, Marta, Brzostek, Katarzyna
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 20.04.2015; Public Library of Science (PLoS)
• Subjects: Antibiotics; Bacteria; Bacterial Proteins - metabolism; Base Sequence; beta-Galactosidase - metabolism; Bile salts; Binding Sites; Biofilms; Biology; Cell division; Deoxyribonucleic acid; DNA; Drug resistance; E coli; Ecological niches; Efflux; Electrophoresis, Polyacrylamide Gel; Electrophoretic mobility; Escherichia coli; Galactosidase; Gel electrophoresis; Gene expression; Gene Expression Regulation, Bacterial; Genes; Genes, MDR; Genes, Reporter; Genetic analysis; Genomes; Gram-negative bacteria; Green Fluorescent Proteins - metabolism; Kinases; Laboratories; Lac Operon; Mass spectrometry; Mass spectroscopy; Membrane proteins; Membrane Proteins - biosynthesis; Molecular Sequence Data; Niches; Operons; Organic chemistry; Plasmids - metabolism; Promoter Regions, Genetic; Promoters; Proteins; Reporter gene; RNA - metabolism; Salmonella; Salmonella enterica; Salts; Signal transduction; Sodium lauryl sulfate; Temperature; Trans-Activators - metabolism; Transcription; Yersinia enterocolitica; Yersinia enterocolitica - metabolism; Yttrium; β-Galactosidase; Poland
• DOI: 10.1371/journal.pone.0124248
• ISSN: 1932-6203

OmpR is a transcriptional regulator implicated in the control of various cellular processes and functions in Enterobacteriaceae. This study was undertaken to identify genes comprising the OmpR regulon in the human gastrointestinal pathogen Yersinia enterocolitica. Derivatives of an ompR-negative strain with random transposon insertions creating transcriptional fusions with the reporter gene lacZ were isolated. These were supplied with the wild-type ompR allele in trans and then screened for OmpR-dependent changes in β-galactosidase activity. Using this strategy, five insertions in genes/operons positively regulated by OmpR and two insertions in genes negatively regulated by this protein were identified. Genetic analysis of one of these fusion strains revealed that the gene acrR, encoding transcriptional repressor AcrR is negatively regulated by OmpR. Differential analysis of membrane proteins by SDS-PAGE followed by mass spectrometry identified the protein AcrB, a component of the AcrAB-TolC multidrug efflux pump, as being positively regulated by OmpR. Analysis of the activity of the acrR and acrAB promoters using gfp fusions confirmed their OmpR-dependent repression and activation, respectively. The identification of putative OmpR-binding sites and electrophoretic mobility shift assays confirmed that this regulator binds specifically to both promoter regions with different affinity. Examination of the activity of the acrR and acrAB promoters after the exposure of cells to different chemicals showed that bile salts can act as an OmpR-independent inducer. Taken together, our findings suggest that OmpR positively controls the expression of the AcrAB-TolC efflux pump involved in the adaptive response of Y. enterocolitica O:9 to different chemical stressors, thus conferring an advantage in particular ecological niches.