title: MexZ-mediated regulation of mexXY multidrug efflux pump expression in Pseudomonas aeruginosa by binding on the mexZ-mexX intergenic DNA.
abstract: MexZ is a transcriptional regulator of the mexXY multidrug transporter operon, which confers aminoglycoside resistance on Pseudomonas aeruginosa. Highly purified MexZ showed direct binding with a specific site of the mexZ-mexX intergenic DNA when probed by a gel retardation assay. Both in vitro chemical cross-linking experiments and an in vivo two-hybrid expression system showed that the active form of MexZ, which is capable of binding the intergenic DNA, appeared to be a dimer. These results explain the mechanism by which MexZ represses transcription of the mexXY operon, but do not explain the substrate-induced hyperproduction of MexXY. The presence of inducer antibiotic in the gel-retardation assay mixture failed to detect altered MexZ-probe DNA interaction suggesting the possible involvement of an additional regulator.
authors.affiliation: Department of Molecular Life Science, Tokai University School of Medicine, 145 Shimokasuya, Isehara-shi, Kanagawa-ken 259-1193, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Matsuo
authors.forename: Shima
authors.initials: S
authors.lastname: Eda
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Gotoh
authors.forename: Eisaku
authors.initials: E
authors.lastname: Yoshihara
authors.forename: Taiji
authors.initials: T
authors.lastname: Nakae
mesh_terms: D000595:Amino Acid Sequence; D000617:Aminoglycosides / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D001483:Base Sequence; D004269:DNA, Bacterial / Q000378:metabolism; D021901:DNA, Intergenic / Q000378:metabolism*; D019281:Dimerization; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D024202:Electrophoretic Mobility Shift Assay; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D009876:Operon; D011485:Protein Binding; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000235:genetics* / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D020798:Two-Hybrid System Techniques
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D021901:DNA, Intergenic; C402791:MexXY protein, Pseudomonas aeruginosa; C402792:MexZ protein, Pseudomonas aeruginosa; D012097:Repressor Proteins