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PMID: 10515918 Published · ppublish English Journal Article Research Support, Non-U.S. Gov't

Characterization of MexT, the regulator of the MexE-MexF-OprN multidrug efflux system of Pseudomonas aeruginosa.

Journal of bacteriology ·Vol. 181 ·No. 20 ·1999-10-00 ·Pages 6300-5

Köhler T, Epp SF, Curty LK, Pechère JC

Abstract

We investigated the regulation of the MexEF-OprN multidrug efflux system of Pseudomonas aeruginosa, which is overexpressed in nfxC-type mutants and confers resistance to quinolones, chloramphenicol and trimethoprim. Sequencing of the DNA region upstream of the mexEF-oprN operon revealed the presence of an open reading frame (ORF) of 304 amino acids encoding a LysR-type transcriptional activator, termed MexT. By using T7-polymerase, a 34-kDa protein was expressed in Escherichia coli from a plasmid carrying the mexT gene. Expression of a mexE::lacZ fusion was 10-fold higher in nfxC-type mutants than in the wild-type strain; however, transcription of mexT as well as the mexT DNA region was unchanged. Located adjacent to mexT but transcribed in opposite direction, the beginning of an ORF termed qrh (quinone oxidoreductase homologue) was identified. Expression of a qrh::lacZ fusion was also found to be activated by MexT. Further, we present evidence for coregulation at the transcriptional and the posttranscriptional level between the MexEF-OprN efflux system and the OprD porin responsible for cross-resistance of nfxC-type mutants to carbapenem antibiotics.

MeSH Terms
4-Quinolones Anti-Infective Agents/metabolism Bacterial Outer Membrane Proteins/biosynthesis,genetics Biological Transport, Active Carbapenems/metabolism Chloramphenicol/metabolism Cloning, Molecular Drug Resistance, Multiple/genetics Gene Expression Regulation, Bacterial Genes, Bacterial Molecular Sequence Data Mutation Operon Phenotype Porins/biosynthesis Pseudomonas aeruginosa/genetics RNA Processing, Post-Transcriptional Sequence Analysis, DNA Transcription, Genetic Trimethoprim/metabolism
Chemicals
4-Quinolones Anti-Infective Agents Bacterial Outer Membrane Proteins Carbapenems OprN protein, Pseudomonas aeruginosa Porins OprD protein, Pseudomonas aeruginosa Chloramphenicol Trimethoprim
Authors & Affiliations
4 authors, click to expand affiliations / ORCID
Köhler T
Department of Genetics, Centre Médical Universitaire, Geneva, Switzerland. [email protected]
Epp S F
Curty L K
Pechère J C
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Article Info
Journal
Journal of bacteriology
Abbr.
J Bacteriol
ISSN
0021-9193
DOI
10.1128/JB.181.20.6300-6305.1999
Email
[email protected]
Published
1999-10-00
Pages
6300-5
Language
English
Region
United States
NLM ID
2985120R
PMCID
PMC103763
Subset
IM
Databases
GENBANK
AJ007825
External Links
PubMed source DOI: 10.1128/JB.181.20.6300-6305.1999 PMC Full Text View journal details
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