A structurally unrelated mimic of a Pseudomonas aeruginosa acyl-homoserine lactone quorum-sensing signal.

The pathogenic bacterium Pseudomonas aeruginosa uses acyl-homoserine lactone quorum-sensing signals to coordinate the expression of a battery of virulence genes in a cascade of regulatory events. The quorum-sensing signal that triggers the cascade is N-3-oxo-dodecanoyl homoserine lactone (3OC12-HSL), which interacts with two signal receptor-transcription factors, LasR and QscR. This signal is base labile, and it is degraded by mammalian PON lactonases. We have identified a structurally unrelated triphenyl mimic of 3OC12-HSL that is base-insensitive and PON-resistant. The triphenyl mimic seems to interact specifically with LasR but not with QscR. In silico analysis suggests that the mimic fits into the 3OC12-HSL-binding site of LasR and makes key contacts with LasR. The triphenyl mimic is an excellent scaffold for developing quorum-sensing inhibitors, and its stability and potency make it ideal for biotechnology uses such as heterologous gene expression.