Characterization of a Phosphotriesterase-Like Lactonase from Sulfolobus solfataricus and Its Immobilization for Disruption of Quorum Sensing

SsoPox, a bifunctional enzyme with organophosphate hydrolase andN -acyl homoserine lactonase activities from the hyperthermophilic archaeonSulfolobus solfataricus , was overexpressed and purified from recombinantPseudomonas putida KT2440 with a yield of 9.4 mg of protein per liter of culture. The enzyme has a preference forN -acyl homoserine lactones (AHLs) with acyl chain lengths of at least 8 carbon atoms, mainly due to lowerKm values for these substrates. The highest specificity constant obtained was forN -3-oxo-decanoyl homoserine lactone (k cat /Km = 5.5 × 103 M−1 ·s−1 ), but SsoPox can also degradeN -butyryl homoserine lactone (C4 -HSL) andN -oxo-dodecanoyl homoserine lactone (oxo-C12 -HSL), which are important for quorum sensing in ourPseudomonas aeruginosa model system. WhenP. aeruginosa PAO1 cultures were grown in the presence of SsoPox-immobilized membranes, the production of C4 -HSL- and oxo-C12 -HSL-regulated virulence factors, elastase, protease, and pyocyanin were significantly reduced. This is the first demonstration that immobilized quorum-quenching enzymes can be used to attenuate the production of virulence factors controlled by quorum-sensing signals.