While P-glycoprotein (Pgp) is the most studied protein involved in resistance to anti-cancer drugs, its mechanism of action is still under debate. Studies of Pgp have used cell lines selected with chemotherapeutics which may have developed many mechanisms of resistance. To eliminate the confounding effects of drug selection on understanding the action of Pgp, we studied cells transiently transf...

AcrAB-TolC is a major efflux pump in Escherichia coli. It was reported that tolC is overexpressed and involves in improving the organic solvent tolerance level in Escherichia coli marR mutants that are resistant to several antibiotics, such as ciprofloxacin. Low and intermediate levels resistance did not improve organic solvent tolerance. Thus, in this descriptive-experimental study it was deci...

Overexpression of MDR1 efflux pump is a major mechanism contributing to drug resistance in Candida albicans, the most common human fungal pathogen. To elucidate the regulatory pathway of drug resistance, we have identified a negative regulator of MDR1 and named it Regulator of Efflux Pump 1 (REP1). Overexpression of REP1 in Saccharomyces cerevisiae increased susceptibility to fluconazole. Furth...

The Na(+)-K(+) pump in the erythrocytes of a mordibly obese patient shows a unique constellation of functional abnormalities. The number of pump units, measured by [(3)H]ouabain binding to intact cells, as well as the enzymatic activity of the (Na(+)-K(+))-dependent ATPase in erythrocyte membranes were found to be markedly increased compared with control cells (18-fold and 14-fold, respectively...

Reduced susceptibility of Listeria monocytogenes to benzalkonium chloride (BC), a quaternary ammonium compound widely used in food processing and hospital environments, is a growing public health and food safety concern. The minimal inhibitory concentration of BC on 392 L. monocytogenes strains from Switzerland (CH) and Finland (FIN) was determined. Within this strain collection, benzalkonium c...

Brain capillary endothelial cells play an important role in ion homeostasis of the brain through the transendothelial transport of Na and K. Since little is known about the regulation of ion transport in these cells, we determined the effect of extracellular potassium concentration ([K]o) on the kinetics of the Na,K-pump in isolated cerebral microvessels using both K uptake and Na efflux as mea...

Copper is an essential nutrient for all aerobic organisms but is toxic in excess. At the host-pathogen interface, macrophages respond to bacterial infection by copper-dependent killing mechanisms, whereas the invading bacteria are thought to counter with an up-regulation of copper transporters and efflux pumps. The tripartite efflux pump CusCBA and its metallochaperone CusF are vital to the det...

The objective of this study was to explore the molecular epidemiology and the genetic support of clinical multidrug resistant (MDR) Acinetobacter baumannii (A. baumannii) isolates in an ICU ward of a comprehensive hospital. A total of 102 non-duplicate drug-resistant A. baumannii isolates were identified and 93 (91.1%) of them were MDR strains. Molecular analysis demonstrated that carbapenemase...

Efflux pumps are membrane transporters that actively extrude various substrates, leading to multidrug resistance (MDR). In this study, we have designed a new test that allows investigating the assembly of the MexA-MexB-OprM efflux pump from the Gram negative bacteria Pseudomonas aeruginosa. The method relies on the streptavidin-mediated pull-down of OprM proteoliposomes upon interaction with Me...

Fluconazole (FLC) remains the antifungal drug of choice for non-life-threatening Candida infections, but drug-resistant strains have been isolated during long-term therapy with azoles. Drug efflux, mediated by plasma membrane transporters, is a major resistance mechanism, and clinically significant resistance in Candida albicans is accompanied by increased transcription of the genes CDR1 and CD...