The Pseudomonas Quinolone Signal (PQS)

Pseudomonas aeruginosa is an opportunistichuman pathogen that routinely appears near the top ofpublic health threat lists worldwide. P. aeruginosa causes in-fections by secreting a wealth of exceptionally active exo-products, leading to tissue damage. The synthesis of manyof these virulence factors is now known to be under the con-trol of the quorum sensing (QS) system.

Over the last15 years, the Pseudomonas quinolone signal (PQS) has beenfound to play a crucial role in QS by linking the two seg-ments (las and rhl) of the P. aeruginosa N-acylhomoserinelactone-dependent QS signaling pathways. Herein, we pres-ent the discovery and elucidation of PQS signaling froma historical perspective, and also outline some of the out-standing research questions that still need to be addressed.Finally, we show how a better understanding of the bio-chemistry underpinning this pathway is leading to the devel-opment of new antimicrobial interventions with clear thera-peutic potential.