Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2001 May;45(5):1550-2.
doi: 10.1128/AAC.45.5.1550-1552.2001.

Absence of mutations in marRAB or soxRS in acrB-overexpressing fluoroquinolone-resistant clinical and veterinary isolates of Escherichia coli

M A Webber  1 , L J Piddock
Affiliations

Absence of mutations in marRAB or soxRS in acrB-overexpressing fluoroquinolone-resistant clinical and veterinary isolates of Escherichia coli

M A Webber et al. Antimicrob Agents Chemother. 2001 May.

Abstract

The amount of acrB, marA, and soxS mRNA was determined in 36 fluoroquinolone-resistant E. coli from humans and animals, 27 of which displayed a multiple-resistance phenotype. acrB mRNA was elevated in 11 of 36 strains. A mutation at codon 45 (Arg-->Cys) in acrR was found in 6 of these 11 strains. Ten of the 36 isolates appeared to overexpress soxS, and five appeared to overexpress marA. A number of mutations were found in the marR and soxR repressor genes, correlating with greater amounts of marA and soxS mRNA, respectively.

PubMed Disclaimer

Figures

FIG. 1
FIG. 1
Overproduction of acrB. The strains that overproduced acrB mRNA (I87, I94, I238, I241, I244, I245, I254 and I279) gave brighter bands than AG102 (which constitutively overexpresses marA mRNA), indicating that they produced more acrB than a Mar mutant strain.
FIG. 2
FIG. 2
Overproduction of soxS. The strains that overproduced soxS mRNA gave intensities of the transcript similar to that of the positive control strain, JTG1078 (Sox +ve). The soxS transcript was barely detectable in wild-type strains (e.g., I113).
See this image and copyright information in PMC

References

    1. Alekshun M N, Levy S B. Regulation of chromosomally mediated multiple antibiotic resistance: the mar regulon. Antimicrob Agents Chemother. 1997;41:2067–2075. - PMC - PubMed
    1. Amabile-Cuevas C F, Demple B. Molecular characterization of the soxRS genes of Escherichia coli: two genes control a superoxide stress regulon. Nucleic Acids Res. 1991;19:4479–4484. - PMC - PubMed
    1. Ariza R R, Li Z, Ringstad N, Demple B. Activation of multiple antibiotic resistance and binding of stress-inducible promoters by Escherichia coli Rob protein. J Bacteriol. 1995;177:1655–1661. - PMC - PubMed
    1. Barbosa T M, Levy S B. Differential expression of over 60 chromosomal genes in Escherichia coli by constitutive expression of MarA. J Bacteriol. 2000;182:3467–3474. - PMC - PubMed
    1. Bennik H J M, Pomposiello P J, Thorne D F, Demple B. Defining a rob regulon in Escherichia coli by using transposon mutagenesis. J Bacteriol. 2000;182:3794–3801. - PMC - PubMed

LinkOut - more resources