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- Title
Regulation of the aceI multidrug efflux pump gene in Acinetobacter baumannii.
- Authors
Liu, Qi; Hassan, Karl A; Ashwood, Heather E; Gamage, Hasinika K A H; Li, Liping; Mabbutt, Bridget C; Paulsen, Ian T
- Abstract
<bold>Objectives: </bold>To investigate the function of AceR, a putative transcriptional regulator of the chlorhexidine efflux pump gene aceI in Acinetobacter baumannii.<bold>Methods: </bold>Chlorhexidine susceptibility and chlorhexidine induction of aceI gene expression were determined by MIC and quantitative real-time PCR, respectively, in A. baumannii WT and ΔaceR mutant strains. Recombinant AceR was prepared as both a full-length protein and as a truncated protein, AceR (86-299), i.e. AceRt, which has the DNA-binding domain deleted. The binding interaction of the purified AceR protein and its putative operator region was investigated by electrophoretic mobility shift assays and DNase I footprinting assays. The binding of AceRt with its putative ligand chlorhexidine was examined using surface plasmon resonance and tryptophan fluorescence quenching assays.<bold>Results: </bold>MIC determination assays indicated that the ΔaceI and ΔaceR mutant strains both showed lower resistance to chlorhexidine than the parental strain. Chlorhexidine-induced expression of aceI was abolished in a ΔaceR background. Electrophoretic mobility shift assays and DNase I footprinting assays demonstrated chlorhexidine-stimulated binding of AceR with two sites upstream of the putative aceI promoter. Surface plasmon resonance and tryptophan fluorescence quenching assays suggested that the purified ligand-binding domain of the AceR protein was able to bind with chlorhexidine with high affinity.<bold>Conclusions: </bold>This study provides strong evidence that AceR is an activator of aceI gene expression when challenged with chlorhexidine. This study is the first characterization, to our knowledge, of a regulator controlling expression of a PACE family multidrug efflux pump.
- Subjects
ACINETOBACTER baumannii; CHLORHEXIDINE; GENE expression; DRUG resistance; STAPHYLOCOCCUS aureus; THERAPEUTICS; ANTIBIOTICS; BACTERIAL proteins; COMPARATIVE studies; DISINFECTION &; disinfectants; DRUG resistance in microorganisms; GENES; RESEARCH methodology; MEDICAL cooperation; RESEARCH; EVALUATION research; GRAM-negative aerobic bacteria; MEMBRANE transport proteins; PHARMACODYNAMICS
- Publication
Journal of Antimicrobial Chemotherapy (JAC), 2018, Vol 73, Issue 6, p1492
- ISSN
0305-7453
- Publication type
journal article
- DOI
10.1093/jac/dky034