tetracycline and phenylalanine-arginine-beta-naphthylamide

Multidrug efflux pumps confer resistance to their bacterial hosts by pumping out a diverse range of compounds, including most antibiotics. Being more familiar with the details of functional dynamics and conformations of these types of pumps could help in discovering approaches to stop them functioning properly. Computational approaches, particularly conventional molecular dynamics simulations followed by diverse post simulation analysis, are powerful methods that help researchers by opening a new window to study phenomena that are not detectable in as much detail in vitro or in vivo as they are in silico. In this study, accelerated molecular dynamics simulations were applied to study the dynamics of AcrB efflux pump transporters in interaction with PAβN and tetracycline as an inhibitor and a substrate, respectively, to compare the differences in the dynamics and consequently the mechanism of action of the pump. The different dynamics for PAβN -bound form of AcrB compared to the TET-bound form is likely to affect the rotating mechanism typically observed for AcrB transporter. This shows the dynamics of the active AcrB transporter is different in a substrate-bound state compared to an inhibitor-bound state. This advances our knowledge and helps to unravel the mechanism of tripartite efflux pumps.

Topics: Anti-Bacterial Agents; Bacterial Proteins; Binding Sites; Dipeptides; Escherichia coli Proteins; Klebsiella pneumoniae; Membrane Transport Proteins; Molecular Dynamics Simulation; Multidrug Resistance-Associated Proteins; Sequence Homology, Amino Acid; Substrate Specificity; Tetracycline

We investigated the involvement of the CmeABC efflux pump in acquired resistance of Campylobacter jejuni to macrolides and tetracycline. Inactivation of the cmeB gene had no effect on macrolide resistance when all copies of the target gene carried an A2074C mutation. In contrast, the CmeABC pump significantly contributed to macrolide resistance when two or three copies of the 23S rRNA had an A2075G transition. Inactivation of the cmeB gene led to restoration of tetracycline susceptibility in the isolates examined. Complete susceptibility to tetracycline or macrolides, however, was not restored when phenylalanine-arginine beta-naphthylamide was used. These data confirm contribution of the CmeABC efflux pump to acquired resistance of Campylobacter jejuni to tetracycline and macrolides.

Topics: Anti-Bacterial Agents; ATP-Binding Cassette Transporters; Campylobacter jejuni; Clarithromycin; Culture Media; Dipeptides; DNA, Bacterial; Drug Resistance, Bacterial; Erythromycin; Macrolides; Microbial Sensitivity Tests; RNA, Ribosomal, 23S; Tetracycline Resistance