Effects of Verapamil and Two Bisbenzylisoquinolines, Curine and Guattegaumerine Extracted from on the Inhibition of ABC Transporters from .

The biological effects of alkaloids, curine, guattegaumerine, and verapamil, on were investigated. These molecules did not inhibit growth but increased the sensitivity of this bacterium to carbenicillin, novobiocin, and erythromycin. The results of another study indicate that curine and guattegaumerine were competitors of verapamil and acted as inhibitors of eukaryotic ABCB1 efflux pump. A BLAST-P carried out between a bacterial MDR transporter LmrA from , a human MDR1/P-glycoprotein (ABCB1), and ABC proteins of highlighted five potential candidates that have this bacterium. A study on the sensitivity to carbenicillin in the presence of verapamil allowed us to identify the product of gene PA1113 as the ABC transporter involved in the influx of carbenicillin. Similarly, novobiocin transport performed in the presence of verapamil and a docking analysis highlighted protein MsbA (Lipid A flippase, gene PA4997) as a potential candidate in novobiocin efflux. MsbA has previously been identified as a multidrug transporter in , and as MsbA presented 76% identity with MsbA, it is possible that novobiocin efflux involves this ABC transporter, accounting for about 30% of the bacterium resistance to this antibiotic.