Dissecting the Multiple Roles of PqsE in Pseudomonas aeruginosa Virulence by Discovery of Small Tool Compounds

Pseudomonas aeruginosa uses quorum sensing (QS) as a cell-to-cell communication system to orchestrate the expression. of virulence determinants. The biosynthesis of the important Pseudomonas quinolone signal (PQS) requires the pqsABCDE operon., Here, PqsE acts, as,a. pathway specific thioesterase, but it also contributes to the regulation of bacterial virulence via an unknown mechanism. In this manuscript, we report the discovery.of PqSE inhibitors as tool compounds to gain further, insights into, its different functions. Differential, scanning fluorimetry (DSF) was used to screen a fragment library, and isothermal titration calorimetry (ITC) was employed as a secondary filter. As proven: by X-ray crystallography, hit molecules bound to the active Center inhibiting PqsE's thioesterase activity in cell-based and in:vitro assays. Notably) the ligands did not affect the levels of the PqsE regulated virulence factor pyocyanin. These findings indicate that the regtilatory function of PqsE is not linked to its, thioesterase activity and must be encoded outside of the active center. This study highlights the potential of fragment based screening for