Antibiotic resistance: multidrug efflux proteins, a common transport mechanism?
Astbury Centre for Structural Molecular Biology, School of Biochemistry and Microbiology, University of Leeds, LS2 9JT, UK.Natural Product Reports (impact factor: 9.79). 09/2005; 22(4):439-51. DOI:10.1039/b413734p pp.439-51
Article: A genomic strategy for cloning, expressing and purifying efflux proteins of the major facilitator superfamily.[show abstract] [hide abstract]
ABSTRACT: A genomic strategy for the overexpression of bacterial multidrug and antibiotic resistance membrane efflux proteins in Escherichia coli is described. Expression is amplified so that the encoded proteins from a range of Gram-positive and Gram-negative bacteria comprise 5% to 35% of E. coli inner membrane protein. Depending upon their topology, proteins are produced with RGS(His)(6)-tag or a Strep-tag at the C terminus. These tags facilitate the purification of the overexpressed proteins in milligram quantities for structural studies. The strategy is illustrated for the bicyclomycin resistance efflux protein, Bcr, of E. coli.Journal of Antimicrobial Chemotherapy 07/2007; 59(6):1265-70. · 5.07 Impact Factor
Article: Pharmacophore-based strategy for the development of general and specific scFv biosensors for abused antibiotics.[show abstract] [hide abstract]
ABSTRACT: We developed fluorescent biosensor systems that are either general or selective to fluoroquinolone antibiotics by using a single-chain variable-fragment (scFv) as a recognition element. The selectivity of these biosensors to fluoroquinolone antibiotics was rationally tuned through the structural modification on the pharmacophore of fluoroquinolone antibiotics and the subsequent selection of scFv receptor modules against these antibiotics-based antigens using phage display. The resulting A2 and F9 scFv's bound to their representative antigen with a moderate affinity (K(D) in micromolar range as determined by surface plasmon resonance). A2 is a specific binder for enrofloxacin and did not cross-react with other fluoroquinolone antibiotics including structurally similar ciprofloxacin, while F9 is a general fluoroquinolone binder that likely bound to the antigen at the common pyridone-carboxylic acid pharmacophore. These scFv-based receptors were successfully applied to the development of one-step fluorescent biosensor which can detect fluoroquinolone antibiotics at concentrations below the level suggested in animal drug application guidelines. The strategy described in this report can be applied to developing convenient field biosensors that can qualitatively detect overused/misused antibiotics in the livestock drinking water.Bioconjugate Chemistry 01/2011; 22(1):88-94. · 4.93 Impact Factor
Article: Evaluation of the effects of galbanic acid from Ferula szowitsiana and conferol from F. badrakema, as modulators of multi-drug resistance in clinical isolates of Escherichia coli and Staphylococcus aureus.[show abstract] [hide abstract]
ABSTRACT: Galbanic acid, a sesquiterpene coumarin from Ferula szowitsiana, and conferol, another sesquiterpene coumarin from F. badrakema, were evaluated for their effects on the reversal of multi-drug resistance in clinical isolates of Staphylococcus aureus and Escherichia coli, respectively. Neither galbanic acid (up to 1000 μg/ml) nor conferol (up to 400 μg/ml) by itself shows any antibacterial activities against tested strains. The minimum inhibitory concentrations (MICs) of ciprofloxacin and tetracycline were determined using macrodilution technique in the presence and absence of sub-inhibitory concentrations of galbanic acid (31.25-1000 μg/ml) or conferol (50-400 μg/ml), however they caused no change in MICs of the antibiotics. Galbanic acid did not show any inhibitory effect on efflux phenomenon of E. coli. This can be related to the outer membrane of gram-negative bacteria which is impermeable to lipophilic compounds or another mechanism rather than efflux responsible for resistance in tested E. coli strains. An inhibitory effect of conferol on the efflux was compared with verapamil as a positive control. Because efflux is the only known mechanism of resistance to ethidium bromide (model efflux substrate) and verapamil reduced MIC of ethidium bromide, efflux mechanism can be considered as one of the resistance mechanisms in tested S. aureus strains. Conferol, however, did not enhance the antibiotic efficacy mediated by inhibiting efflux pumps in bacteria.Research in pharmaceutical sciences 01/2010; 5(1):21-8.
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