Dataset Information

Expression of acrA and acrB Genes in Esherichia coli Mutants with or without marR or acrR Mutations.

ABSTRACT:

Objective(s)

The major antibiotic efflux pump of Esherichia coli is AcrAB-TolC. The first part of the pump, AcrAB, is encoded by acrAB operon. The expression of this operon can be kept elevated by overexpression of an activator, MarA following inactivation of MarR and AcrR repressors due to mutation in encoding genes, marR and acrR, respectively. The aims of this research were to use E. coli mutants with or without mutation in marR to search for the presence of possible mutation in acrR and to quantify the expression of acrAB.

Materials and methods

The DNA binding region of acrR gene in these mutants were amplified by PCR and sequenced. The relative expression of acrA and acrB were determined by real time PCR.

Results

RESULTS showed that W26 and C14 had the same mutation in acrR, but none of the mutants overexpressed acrA and acrB in comparison with wild type strain.

Conclusions

The effect of marR or acrR mutation on acrAB overexpression is dependent on levels of resistance to tetracycline and ciprofloxacin.

SUBMITTER: Pourahmad Jaktaji R

PROVIDER: S-EPMC3933802 | biostudies-literature | 2013 Dec

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Expression of acrA and acrB Genes in Esherichia coli Mutants with or without marR or acrR Mutations.

Pourahmad Jaktaji Razieh R Jazayeri Nasim N

Iranian journal of basic medical sciences 20131201 12

<h4>Objective(s)</h4>The major antibiotic efflux pump of Esherichia coli is AcrAB-TolC. The first part of the pump, AcrAB, is encoded by acrAB operon. The expression of this operon can be kept elevated by overexpression of an activator, MarA following inactivation of MarR and AcrR repressors due to mutation in encoding genes, marR and acrR, respectively. The aims of this research were to use E. coli mutants with or without mutation in marR to search for the presence of possible mutation in acrR ...[more]

PMID: 24570831

Similar Datasets

Project description:UnlabelledThe AcrAB-TolC system in Escherichia coli is an intrinsic RND-type multidrug efflux transporter that functions as a tripartite complex of the inner membrane transporter AcrB, the outer membrane channel TolC, and the adaptor protein AcrA. Although the crystal structures of each component of this system have been elucidated, the crystal structure of the whole complex has not been solved. The available crystal structures have shown that AcrB and TolC function as trimers, but the number of AcrA molecules in the complex is now under debate. Disulfide chemical cross-linking experiments have indicated that the stoichiometry of AcrB-AcrA-TolC is 1:1:1; on the other hand, recent cryo-electron microscopy images of AcrAB-TolC suggested a 1:2:1 stoichiometry. In this study, we constructed 1:1-fixed AcrB-AcrA fusion proteins using various linkers. Surprisingly, all the 1:1-fixed linker proteins showed drug export activity under both acrAB-deficient conditions and acrAB acrEF double-pump-knockout conditions regardless of the lengths of the linkers. Finally, we optimized a shorter linker lacking the conformational freedom imparted by the AcrB C terminus. These results suggest that a complex with equal amounts of AcrA and AcrB is sufficient for drug export function.ImportanceThe structure and stoichiometry of the RND-type multidrug exporter AcrB-AcrA-TolC complex are still under debate. Recently, electron microscopic images of the AcrB-AcrA-TolC complex have been reported, suggesting a 1:2:1 stoichiometry. However, we report here that the AcrB-AcrA 1:1 fusion protein is active for drug export under acrAB-deficient conditions and also under acrAB acrEF double-deficient conditions, which eliminate the aid of free AcrA and its close homolog AcrE, indicating that the AcrB-AcrA 1:1 stoichiometry is enough for drug export function. In addition, the AcrB-AcrA fusion protein can function without the aid of free AcrA. We believe that these results are very important for considering the structure and mechanism of AcrAB-TolC-mediated multidrug export.

Dataset Information

Expression of acrA and acrB Genes in Esherichia coli Mutants with or without marR or acrR Mutations.

Objective(s)

Materials and methods

Results

Conclusions

Publications

Expression of acrA and acrB Genes in Esherichia coli Mutants with or without marR or acrR Mutations.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets