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...

AcrAB-TolC is the major multidrug efflux system in Enterobacteriaceae recognizing structurally unrelated molecules including antibiotics, dyes, and detergents. Additionally, in Escherichia coli it mediates resistance to bile salts. In the plant pathogen Erwinia amylovora AcrAB-TolC is required for virulence and phytoalexin resistance. Exchange analysis of AcrAB-TolC was conducted by complementi...

The TolC protein of Escherichia coli, through its interaction with AcrA and AcrB, is thought to form a continuous protein channel that expels inhibitors from the cell. Consequently, tolC null mutations display a hypersensitive phenotype. Here we report the isolation and characterization of tolC missense mutations that direct the synthesis of mutant TolC proteins partially disabled in their effl...

In bacterial drug resistance and virulence pumps, an inner membrane (IM) transporter and periplasmic adaptor recruit an outer membrane (OM) trimeric TolC exit duct that projects an α-helical tunnel across the periplasm. The TolC periplasmic entrance is closed by densely packed α-helical coiled coils, inner H7/H8, and outer H3/H4, constrained by a hydrogen bond network. On recruitment, these coi...

A study examining the influence of TolC on AcrA, AcrR, and MarR1 mutants indicates that functional TolC is required for the operation of the AcrAB efflux system and for the expression of the Mar phenotype. That the effect of TolC on the AcrAB pump is not regulatory in nature is shown by studies measuring the influence of a tolC::Tn10 insertion mutation on the expression of an acrA::lacZ reporte...

Development of fluoroquinolone resistance can involve several mechanisms that include chromosomal mutations in genes ( gyrAB and parCE ) encoding the target bacterial topoisomerase enzymes, increased expression AcrAB-TolC efflux system, acquisition transmissible quinolone-resistance genes. In this study, 176 Salmonella isolates from animals with a broad range ciprofloxacin MICs were collected t...

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...

Bacteria such as Escherichia coli and Pseudomonas aeruginosa expel antibiotics and other inhibitors via tripartite multidrug efflux pumps spanning the inner and outer membranes and the intervening periplasmic space. A key event in pump assembly is the recruitment of an outer membrane-anchored TolC exit duct by the adaptor protein of a cognate inner membrane translocase, establishing a contiguou...

The Hly translocator complex of Escherichia coli catalyzes type I secretion of the toxin hemolysin A (HlyA). In this complex, HlyB is an inner membrane ABC (ATP Binding Cassette)-type transporter, TolC is an outer membrane channel protein, and HlyD is a periplasmic adaptor anchored in the inner membrane that bridges HlyB to TolC. This tripartite organization is reminiscent of that of drug efflu...