A Coculture-Based Approach for Screening Campaigns Aimed at Identifying Novel Pseudomonas aeruginosa Quorum Sensing Inhibitors.

Quorum sensing (QS) is recognized as a promising target for the identification of anti-virulence drugs hampering Pseudomonas aeruginosa adaptability to the host environment and pathogenicity. Consequently, a number of studies in the last decade focused on the identification of small molecules or proteins with anti-QS activity, mainly targeting the las QS system, which is based on N-3-oxododecanoyl-homoserine lactone (3OC-HSL) as signal molecule. Different experimental approaches have been successfully used to identify QS blockers interfering with the activity/stability of the 3OC-HSL receptor LasR, with the functionality of the 3OC-HSL synthase LasI, or with the stability/bioavailability of the 3OC-HSL signal molecule itself.Here we describe the use of a high-throughput screening system for the identification of novel las QS inhibitors based on the cocultivation of P. aeruginosa wild type and the P. aeruginosa-derived biosensor strain PA14-R3, in which light emission relies on the ability of the wild type strain to synthesize 3OC-HSL and of the biosensor strain to perceive this signal molecule. With respect to other screening systems, this method has the advantage of being cost-effective and allowing the identification of compounds targeting, besides 3OC-HSL reception, any cellular process critical for the functionality of the las QS system, including 3OC-HSL synthesis and secretion.