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. 2002 Aug;184(15):4308-12.
doi: 10.1128/JB.184.15.4308-4312.2002.

The mexR repressor of the mexAB-oprM multidrug efflux operon in Pseudomonas aeruginosa: characterization of mutations compromising activity

Lateef Adewoye  1 , Ainsley Sutherland, Ramakrishnan Srikumar, Keith Poole
Affiliations

The mexR repressor of the mexAB-oprM multidrug efflux operon in Pseudomonas aeruginosa: characterization of mutations compromising activity

Lateef Adewoye et al. J Bacteriol. 2002 Aug.

Abstract

Mutations in mexR yield a multidrug resistance phenotype in nalB mutants of Pseudomonas aeruginosa as a result of derepression of the mexAB-oprM multidrug efflux operon. MexR produced by several nalB strains carried single amino acid changes that compromised MexR stability or its ability to dimerize. Changes at residues L95 and R21, however, produced a stable MexR protein capable of dimerization and, thus, likely compromised DNA binding.

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Figures

FIG. 1.
FIG. 1.
Expression of MexR in nalB mutants of P. aeruginosa. Soluble extracts of MexAB-OprM hyperexpressing multidrug-resistant strains of P. aeruginosa carrying mutations in mexR (and their parental strains) were electrophoresed on sodium dodecyl sulfate-polyacrylamide (15% [wt/vol]) gels and immunoblotted using antibodies to MexR. Lane 1, P. aeruginosa PAO1 strain K767 (MexRWT); lane 2, strain K1454 (nalC); lane 3, OCR1 (MexRR70W); lane 4, P. aeruginosa PAO503 (MexRWT); lane 5, K1655 (MexRR83H); lane 6, K1656 (MexRR83H); lane 7, K1657 (MexRR91H); lane 8, K1658 (MexRL13M); lane 9, K1647 (MexRA110T); lane 10, K1646 (MexRR59C); lane 11, K1648 (MexRG58E); lane 12, K1649 (MexRL95F); lane 13, K1651 (MexRT69I); lane 14, K1652 (MexRR21W); lane 15, K1653 (MexRL80P); lane 16, K1654 (MexRR70W); lane 17, P. aeruginosa PAO1 strain H103 (MexRWT); lane 18, K1462 (MexRL57R); lane 19, K1463 (MexRT130P). The impact of the nalB mutation on MexR in each strain is indicated in parentheses, with the exception of K1455, which is a nalC strain that hyperproduces MexAB-OprM as a result of an unknown mutation. The gel as presented is a composite assembled from lanes of the same gel.
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