mvaT mutation modifies the expression of the Pseudomonas aeruginosa multidrug efflux operon mexEF-oprN

FEMS Microbiol Lett. 2006 Feb;255(2):247-54. doi: 10.1111/j.1574-6968.2005.00075.x.


Pseudomonas aeruginosa carries several multidrug efflux operons, including mexEF-oprN, that contribute to its resistance to multiple antibiotics. mvaT affects the expression of several P. aeruginosa genes. In this study, we show that the mvaT mutant PAODeltamvaT is more resistant than its parent PAO1 strain to chloramphenicol and norfloxacin but more sensitive to imipenem; yet both were less resistant to chloramphenicol, norfloxacin, and imipenem than 'typical'nfxC-type mutants. Neither strain carries the deletion described for nfxC-type mutants in mexT, the mexEF-oprN regulatory gene. Expression of mexEF-oprN is increased by five- to sixfold in PAODeltamvaT, while the expression of oprD is reduced by approximately twofold. mvaT mutation had no effect on the expression of other multidrug resistance operons, although it increased the expression of several ATP-binding cassette transporter genes. We show that mvaT mutation does not affect mexEF-oprN expression through mexT or mexS. We also explored several other potential mechanisms.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Anti-Bacterial Agents / pharmacology*
  • Bacterial Outer Membrane Proteins / genetics
  • Bacterial Outer Membrane Proteins / metabolism*
  • Bacterial Proteins / genetics*
  • Drug Resistance, Multiple, Bacterial*
  • Gene Expression Regulation, Bacterial*
  • Humans
  • Membrane Transport Proteins / genetics
  • Membrane Transport Proteins / metabolism
  • Microbial Sensitivity Tests
  • Mutation*
  • Oligonucleotide Array Sequence Analysis
  • Operon*
  • Pseudomonas aeruginosa / drug effects*
  • Pseudomonas aeruginosa / genetics
  • Trans-Activators / genetics*


  • Anti-Bacterial Agents
  • Bacterial Outer Membrane Proteins
  • Bacterial Proteins
  • Membrane Transport Proteins
  • MvaT protein, Pseudomonas
  • OprN protein, Pseudomonas aeruginosa
  • Trans-Activators