A genetic platform to investigate the functions of bacterial drug efflux pumps.

Efflux pumps are a serious challenge for the development of antibacterial agents. Overcoming efflux requires an in-depth understanding of efflux pump functions, specificities and the development of inhibitors. However, the complexities of efflux networks have limited such studies. To address these challenges, we generated Efflux KnockOut-35 (EKO-35), a highly susceptible Escherichia coli strain lacking 35 efflux pumps. We demonstrate the use of this strain by constructing an efflux platform comprising EKO-35 strains individually producing efflux pumps forming tripartite complexes with TolC. This platform was profiled against a curated diverse compound collection, which enabled us to define physicochemical properties that contribute to transport. We also show the E. coli drug efflux network is conditionally essential for growth, and that the platform can be used to investigate efflux pump inhibitor specificities and efflux pump interplay. We believe EKO-35 and the efflux platform will have widespread application for the study of drug efflux.