The AcrAB-TolC efflux pump plays an intrinsic role in resistance to hydrophobic solvents in Escherichia coli. E. coli OST5500 is hypersensitive to solvents due to inactivation of the acrB gene by insertion of IS30. Suppressor mutants showing high solvent resistance were isolated from OST5500. These mutants produced high levels of AcrE and AcrF proteins, which were not produced in OST5500, and i...

26 Control of membrane permeability is a key step in regulating the intracellular 27 concentration of antibiotics. Efflux pumps confer innate resistance to a wide 28 range of toxic compounds such as antibiotics, dyes, detergents and 29 disinfectants in members of the Enterobacteriaceae. The AcrAB-TolC efflux 30 pump is involved in multidrug resistance in E. cloacae. However, the underlying 31 m...

Members of the resistance-nodulation-division (RND) family of efflux pumps, such as AcrAB-TolC of Escherichia coli, play major roles in multidrug resistance (MDR) in Gram-negative bacteria. A strategy for combating MDR is to develop efflux pump inhibitors (EPIs) for use in combination with an antibacterial agent. Here, we describe MBX2319, a novel pyranopyridine EPI with potent activity against...

AcrAB-TolC is a major efflux pump in Escherichia coli. It was reported that tolC is overexpressed and involves in improving the organic solvent tolerance level in Escherichia colimarR mutants that are resistant to several antibiotics, such as ciprofloxacin. Low and intermediate levels resistance did not improve organic solvent tolerance. Thus, it was decided to measure tolC expression and organ...

The efflux pump AcrAB is important in the antibiotic resistance and virulence of several pathogenic bacteria. We report that deletion of the Yersinia pestis AcrAB-TolC homolog leads to increased susceptibility to diverse substrates, including, though unlike in Escherichia coli, the aminoglycosides. Neither is the Y. pestis pump affected by the efflux pump inhibitor phenylalanine-arginine beta-n...

OBJECTIVES The transcriptional activator RamA regulates production of the multidrug resistance efflux AcrAB-TolC system in several Enterobacteriaceae. This study investigated factors that lead to increased expression of ramA. METHODS In order to monitor changes in ramA expression, the promoter region of ramA was fused to a gfp gene encoding an unstable green fluorescence protein (GFP) on the ...

Background: Multidrug-resistant efflux pumps are one of the most significant methods by which bacteria can evade effects numerous antimicrobials. The aim this study was to determine prevalence multidrug-resistant MDR, extremely drug-resistant XDR, and pan-drug-resistant PDR K. pneumoniae phenotypes in clinical isolates, as well examine detection pump genes ompK35, ompK36, tolC, acrAB strains.&#...

AcrAB exports some beta-lactam antibiotics in the periplasm out of cells via an outer-membrane channel, TolC. It has been reported that eight drug transporters in Escherichia coli cooperate with TolC. In this study, the roles of the drug exporters of E. coli in beta-lactam resistance were examined. We found that five of five resistance-nodulation-cell division-type drug exporters confer beta-la...

Carbon Storage Regulator A (CsrA) is an RNA binding protein that acts as a global regulator of diverse genes. Using a combination of genetics and biochemistry we show that CsrA binds directly to the 5' end of the transcript encoding AcrAB. Deletion of csrA or mutagenesis of the CsrA binding sites reduced production of both AcrA and AcrB. Nucleotide substitutions at the 5' UTR of acrA mRNA that ...

UNLABELLED Bacteria use multidrug efflux pumps to export drugs and toxic compounds out of the cell. One of the most important efflux pumps in Escherichia coli is the AcrAB-TolC system. Small regulatory RNAs (sRNAs) are known to be major posttranscriptional regulators that can enhance or repress translation by binding to the 5' untranslated region (UTR) of mRNA targets with the help of a chapero...