-!- Acyl-homoserine lactones (AHLs) are produced by a number of bacterial species and are used by them to regulate the expression of virulence genes in a process known as quorum-sensing. -!- Each bacterial cell has a basal level of AHL and, once the population density reaches a critical level, it triggers AHL-signaling which, in turn, initiates the expression of particular virulence genes. -!- Plants or animals capable of degrading AHLs would have a therapeutic advantage in avoiding bacterial infection as they could prevent AHL- signaling and the expression of virulence genes in quorum-sensing bacteria. -!- This quorum-quenching enzyme removes the fatty-acid side chain from the homoserine lactone ring of AHL-dependent quorum-sensing signal molecules. -!- It has broad specificity for AHLs with side changes ranging in length from 11 to 14 carbons. -!- Substituents at the 3'-position, as found in N-(3-oxododecanoyl)-L- homoserine lactone, do not affect this activity.