title: Characterisation of the organophosphate hydrolase catalytic activity of SsoPox.
abstract: SsoPox is a lactonase endowed with promiscuous phosphotriesterase activity isolated from Sulfolobus solfataricus that belongs to the Phosphotriesterase-Like Lactonase family. Because of its intrinsic thermal stability, SsoPox is seen as an appealing candidate as a bioscavenger for organophosphorus compounds. A comprehensive kinetic characterisation of SsoPox has been performed with various phosphotriesters (insecticides) and phosphodiesters (nerve agent analogues) as substrates. We show that SsoPox is active for a broad range of OPs and remains active under denaturing conditions. In addition, its OP hydrolase activity is highly stimulated by anionic detergent at ambient temperature and exhibits catalytic efficiencies as high as k(cat)/K(M) of 10(5) M(-1)s(-1) against a nerve agent analogue. The structure of SsoPox bound to the phosphotriester fensulfothion reveals an unexpected and non-productive binding mode. This feature suggests that SsoPox's active site is sub-optimal for phosphotriester binding, which depends not only upon shape but also on localised charge of the ligand.
authors.affiliation: URMITE UMR CNRS-IRD 6236, IFR48, Faculté de Médecine et de Pharmacie, Université de la Méditerranée, Marseille, France.
authors.forename: Julien
authors.initials: J
authors.lastname: Hiblot
authors.forename: Guillaume
authors.initials: G
authors.lastname: Gotthard
authors.forename: Eric
authors.initials: E
authors.lastname: Chabriere
authors.forename: Mikael
authors.initials: M
authors.lastname: Elias
mesh_terms: D001665:Binding Sites; D055162:Biocatalysis; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D003902:Detergents / Q000737:chemistry; D007700:Kinetics; D062105:Molecular Docking Simulation; D009943:Organophosphorus Compounds / Q000737:chemistry / Q000378:metabolism; D009946:Organothiophosphorus Compounds / Q000737:chemistry; D010261:Paraoxon / Q000737:chemistry / Q000378:metabolism; D010744:Phosphoric Monoester Hydrolases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D048229:Sulfolobus solfataricus / Q000201:enzymology
chemical_list: D003902:Detergents; D009943:Organophosphorus Compounds; D009946:Organothiophosphorus Compounds; C045290:phosphorylphosphatase; D010744:Phosphoric Monoester Hydrolases; D010261:Paraoxon; C073264:fensulfothion