Catalyzes the deacylation of acyl-homoserine lactone (AHL or acyl-HSL), releasing homoserine lactone (HSL) and the corresponding fatty acid. Possesses a specificity for the degradation of long-chain acyl-HSLs (side chains of 11 to 14 carbons in length). Degrades 3-oxo-C12-HSL, one of the two main AHL signal molecules of P.aeruginosa, and thereby functions as a quorum quencher, inhibiting the las quorum-sensing system. Therefore, may enable P.aeruginosa to modulate its own quorum-sensing-dependent pathogenic potential. Also appears to be required for pyoverdin biosynthesis. an N-acyl-L-homoserine lactone + H2O = a carboxylate + L-homoserine lactone Heterodimer of an alpha subunit and a beta subunit processed from the same precursor. Up-regulated under iron starvation conditions. A variable cleavage site between the alpha-subunit and the spacer peptide was observed: Ala-194 may be a part of the alpha-subunit or the spacer peptide. This step of the maturation process may not be very specific. AHL-mediated signaling mediates quorum sensing in many species of Proteobacteria, regulating hundreds of genes, including many that code for extracellular virulence factors. Belongs to the peptidase S45 family.