OBJECTIVES Multidrug efflux pumps mediate resistance to antibiotics and other toxic compounds. We studied the role of AcrAB-TolC, the main efflux pump in Escherichia coli, in regulating gene expression. METHODS Deletion mutants, an acrABp-lacZ fusion and reverse transcription-real-time quantitative PCR experiments were used to study the role of AcrAB-TolC and metabolism in regulating gene exp...

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...

Previously, we found that the quorum sensing transcription factor SdiA up-regulates AcrAB. Others found that a 4-quinolone was a quorum-sensing signal in Pseudomonas aeruginosa. In Escherichia coli, there are at least three multidrug transporters (AcrAB/TolC, MdfA, and NorE) that exude fluoroquinolones. Here, we show that DeltaacrAB, tolC210, or DeltanorE mutants have the same growth rate as WT...

A spontaneous mutant (M113) of Escherichia coli AG100 with an unstable multiple antibiotic resistance (Mar) phenotype was isolated in the presence of tetracycline. Two mutations were found: an insertion in the promoter of lon (lon3::IS186) that occurred first and a subsequent large tandem duplication, dupIS186, bearing the genes acrAB and extending from the lon3::IS186 to another IS186 present ...

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...

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 ...

About 10% of the nalidixic acid-resistant (Nal(r)) mutants in a transposition-induced library exhibited a growth factor requirement as the result of cysH, icdA, metE, or purB mutation. Resistance in all of these mutants required a functional AcrAB-TolC efflux pump, but the EmrAB-TolC pump played no obvious role. Transcription of acrAB was increased in each type of Nal(r) mutant. In the icdA and...

Growth of Escherichia coli is inhibited upon exposure to a large volume of a harmful solvent, and there is an inverse correlation between the degree of inhibition and the log P(OW) of the solvent, where P(OW) is the partition coefficient measured for the partition equilibrium established between the n-octanol and water phases. The AcrAB-TolC efflux pump system is involved in maintaining intrins...