The Pseudomonas Quinolone Signal (PQS)

Pseudomonas aeruginosa is an opportunistic human pathogen that routinely appears near the top of public health threat lists worldwide. P. aeruginosa causes infections by secreting a wealth of exceptionally active exoproducts, leading to tissue damage. The synthesis of many of these virulence factors is now known to be under the control of the quorum sensing (QS) system. Over the last 15 years, the Pseudomonas quinolone signal (PQS) has been found to play a crucial role in QS by linking the two segments (las and rhl) of the P. aeruginosa N-acylhomoserine lactone-dependent QS signaling pathways. Herein, we present the discovery and elucidation of PQS signaling from a historical perspective, and also outline some of the outstanding research questions that still need to be addressed. Finally, we show how a better understanding of the biochemistry underpinning this pathway is leading to the development of new antimicrobial interventions with clear therapeutic potential.