Competitive Live-Cell Profiling Strategy for Discovering Inhibitors of the Quinolone Biosynthesis of Pseudomonas aeruginosa

Abstract

Quinolones of the human pathogenPseudomonas aeruginosaserve as antibacterial weapons and quorum sensing signals and coordinate the production of important virulence factors. A central enzyme for the biosynthesis of these quinolones is the synthetase PqsD. We developed an activity-based probe strategy that allows to screen for PqsD inhibitors in a cellular model system of live cells ofEscherichia colioverexpressing PqsD. This strategy allowed us to determine IC50values for PqsD inhibition directly in live cells. Our most potent inhibitors were derived from the anthranilic acid core of the native substrate and resulted in single-digit micromolar IC50values. The effectiveness of our approach was ultimately demonstrated inP. aeruginosaby the complete shutdown of the production of quinolone quorum sensing signals and quinoloneN-oxides and a considerable inhibition of the production of phenazine virulence factors.