title: A new member of the tripartite multidrug efflux pumps, MexVW-OprM, in Pseudomonas aeruginosa.
abstract: OBJECTIVE
  Multidrug efflux pumps are thought to be involved in mediating multidrug resistance in Pseudomonas aeruginosa. Here we aim to characterize hitherto uncharacterized multidrug efflux pumps from P. aeruginosa.
  
  
  METHODS
  We isolated a mutant, YM442, which showed elevated resistance to several antimicrobial agents from P. aeruginosa YM44 lacking four major multidrug efflux pumps, MexAB, MexCD-OprJ, MexEF-OprN and MexXY. We cloned genes responsible for the resistance from chromosomal DNA of YM442 using YM44 as host.
  
  
  RESULTS
  We designated the genes mexVW. Introduction of a recombinant plasmid pTAJ2 carrying the mexVW into YM44 cells conferred resistance to fluoroquinolones, tetracycline, chloramphenicol, erythromycin, ethidium bromide and acriflavine. Elevated ethidium bromide extrusion was observed with cells of YM442 and of YM44/pTAJ2. An outer membrane protein OprM was able to cooperate with MexVW. Elevated expression of the mexV gene was observed with YM442 compared with YM44.
  
  
  CONCLUSIONS
  MexV (membrane fusion protein)-MexW (RND-type membrane protein)-OprM is a tripartite multidrug efflux pump. It is suggested that other outer membrane component(s) could cooperate with MexVW.
authors.affiliation: Department of Microbiology, Faculty of Pharmaceutical Sciences, Okayama University, Tsushima, Okayama, 700-8530, Japan.
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.forename: Takehiko
authors.initials: T
authors.lastname: Mima
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Komori
authors.forename: Yuji
authors.initials: Y
authors.lastname: Morita
authors.forename: Teruo
authors.initials: T
authors.lastname: Kuroda
authors.forename: Tohru
authors.initials: T
authors.lastname: Mizushima
authors.forename: Tomofusa
authors.initials: T
authors.lastname: Tsuchiya
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D024901:Drug Resistance, Multiple, Bacterial / Q000502:physiology*; D004996:Ethidium / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D001425:Bacterial Outer Membrane Proteins; D026901:Membrane Transport Proteins; C402263:OprM protein, Pseudomonas aeruginosa; D004996:Ethidium