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.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Aminoglycosides / pharmacology
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Anti-Bacterial Agents / pharmacology
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Bacterial Proteins / chemistry
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Bacterial Proteins / genetics*
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Bacterial Proteins / isolation & purification
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Bacterial Proteins / metabolism*
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Base Sequence
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DNA, Bacterial / metabolism
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DNA, Intergenic / metabolism*
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Dimerization
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Drug Resistance, Multiple, Bacterial / genetics*
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Electrophoretic Mobility Shift Assay
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Gene Expression Regulation, Bacterial*
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Molecular Sequence Data
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Operon
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Protein Binding
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Pseudomonas aeruginosa / drug effects*
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Pseudomonas aeruginosa / genetics*
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Pseudomonas aeruginosa / metabolism
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Repressor Proteins / genetics
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Repressor Proteins / metabolism
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Transcription, Genetic
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Two-Hybrid System Techniques
Substances
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Aminoglycosides
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Anti-Bacterial Agents
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Bacterial Proteins
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DNA, Bacterial
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DNA, Intergenic
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MexXY protein, Pseudomonas aeruginosa
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MexZ protein, Pseudomonas aeruginosa
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Repressor Proteins