The Burkholderia pseudomallei BpeAB-OprB efflux pump: expression and impact on quorum sensing and virulence.
BpeAB-OprB is a multidrug efflux pump of the bacterial pathogen Burkholderia pseudomallei and is responsible for conferring antimicrobial resistance to aminoglycosides and macrolides. Expression of bpeAB-oprB is inducible by its substrate erythromycin and upon entry into stationary phase. BpeR, a member of the TetR family, functions as a repressor of the bpeAB-oprB operon. bpeR expression was similarly induced at stationary phase but lagged behind the induction of bpeAB-oprB expression. The induction of bpeAB-oprB expression could be advanced to the early exponential phase by exogenous addition of the B. pseudomallei autoinducers N-octanoyl-homoserine lactone (C8HSL) and N-decanoyl-homoserine lactone (C10HSL), suggesting that the bpeAB-oprB operon may be quorum regulated. On the other hand, acyl-homoserine lactone (acyl-HSL) production was undetectable in the bpeAB-null mutant and strains which overexpress bpeR. The failure of these strains to produce acyl-HSLs seemed to be at the level of synthesis of acyl-HSLs, as growth-phase-dependent expression of the autoinducer synthase BpsI was abolished in the bpeAB-null mutant. bpsI expression remained growth phase dependent in the bpeR mutant which had functional BpeAB-OprB. BpeAB-OprB function is likewise necessary for optimal production of quorum-sensing-controlled virulence factors such as siderophore and phospholipase C and for biofilm formation. Cell invasion and cytotoxicity towards human lung epithelial (A549) and human macrophage (THP-1) cells were also significantly attenuated in both the bpeAB mutant and bpeR-overexpressing strains, thus suggesting the possibility of attenuating B. pseudomallei virulence using inhibitors of the BpeAB-OprB efflux pump.
Department of Biochemistry, National University of Singapore.
Ying Ying
YY
Chan
Kim Lee
KL
Chua
D001425:Bacterial Outer Membrane Proteins / Q000235:genetics* / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D016957:Burkholderia pseudomallei / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity*; D017931:DNA Primers; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D004917:Erythromycin / Q000494:pharmacology; D005839:Gentamicins / Q000494:pharmacology; D007700:Kinetics; D026901:Membrane Transport Proteins / Q000235:genetics* / Q000378:metabolism*; D008826:Microbial Sensitivity Tests; D016296:Mutagenesis; D033903:Periplasmic Proteins / Q000235:genetics* / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013307:Streptomycin / Q000494:pharmacology; D014774:Virulence / Q000235:genetics
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; C485375:BpeA protein, Burkholderia pseudomallei; C485376:BpeB protein, Burkholderia pseudomallei; D017931:DNA Primers; D005839:Gentamicins; D026901:Membrane Transport Proteins; C485377:OprB protein, Burkholderia pseudomallei; D033903:Periplasmic Proteins; D011994:Recombinant Proteins; D004917:Erythromycin; D013307:Streptomycin