title: Transcriptional regulation of mexR, the repressor of Pseudomonas aeruginosa mexAB-oprM multidrug efflux pump.
abstract: The transcription start site of mexR, encoding the repressor of the Pseudomonas aeruginosa mexAB-oprM multidrug efflux pump, has been determined by S1 mapping. One signal corresponding to a single promoter has been found, whereas three major signals were observed for the mexA messenger. Further analysis demonstrated that mexA has just one promoter that overlaps with the mexR promoter, with the other two signals observed by S1 probably being the consequence of RNA processing. Transcription of mexR and mexA from the aforementioned promoters is regulated by MexR. We show that bacterial growth phase affects expression of these promoters as well. mexR expression was higher at the exponential growth phase and declined afterwards, whereas mexA expression was triggered at the onset of the stationary growth phase. A model for the regulation of mexR and mexA expression, which includes an analysis of the interplay between both promoters, is proposed.
authors.affiliation: Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología (CSIC), Campus Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049, Spain.
authors.forename: Patricia
authors.initials: P
authors.lastname: Sánchez
authors.forename: Fernando
authors.initials: F
authors.lastname: Rojo
authors.forename: José L
authors.initials: JL
authors.lastname: Martínez
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D024901:Drug Resistance, Multiple, Bacterial; D015964:Gene Expression Regulation, Bacterial; D026901:Membrane Transport Proteins; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D011550:Pseudomonas aeruginosa / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D026901:Membrane Transport Proteins; C118598:MexA protein, Pseudomonas aeruginosa; C118597:MexB protein, Pseudomonas aeruginosa; C423620:MexR protein, Pseudomonas aeruginosa; C402263:OprM protein, Pseudomonas aeruginosa; D012097:Repressor Proteins