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. 1998 Nov;180(22):6072-5.
doi: 10.1128/JB.180.22.6072-6075.1998.

The Escherichia coli cmlA gene encodes the multidrug efflux pump Cmr/MdfA and is responsible for isopropyl-beta-D-thiogalactopyranoside exclusion and spectinomycin sensitivity

C Bohn  1 , P Bouloc
Affiliations

The Escherichia coli cmlA gene encodes the multidrug efflux pump Cmr/MdfA and is responsible for isopropyl-beta-D-thiogalactopyranoside exclusion and spectinomycin sensitivity

C Bohn et al. J Bacteriol. 1998 Nov.

Abstract

Expression of cloned genes from isopropyl-beta-D-thiogalactopyranoside (IPTG)-regulated promoters is lowered when the Escherichia coli CmlA/Cmr/MdfA efflux pump is overexpressed, probably due to IPTG exclusion from the cytoplasm. The previously reported cmlA1 mutation confers a similar phenotype. cmlA1 contains an IS30 insertion upstream of cmr/mdfA, which creates a putative promoter. CmlA overproduction also causes spectinomycin hypersensitivity.

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Figures

FIG. 1
FIG. 1
The cmlA1 mutation is due to IS30 transposition upstream of the cmlA (cmr/mdfA) gene. The sequence generated by the insertion creates a putative ς70 promoter as indicated in the expanded region of the IS30-cmlA junction.
FIG. 2
FIG. 2
Kinetics of endogenous β-galactosidase specific activities of strains PhB1010 (parental strain) (closed circle), PhB1011 (cmlA1) (open circle), PhB1010/pBR322 (closed square), and PhB1010/pBRCMLA (open square) after addition (at time zero) of 5 × 10−5 M IPTG to broth. β-Galactosidase was assayed according to Miller (20).
See this image and copyright information in PMC

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