title: Structural determinants of the high thermal stability of SsoPox from the hyperthermophilic archaeon Sulfolobus solfataricus.
abstract: Organophosphates (OPs) constitute the largest class of insecticides used worldwide and certain of them are potent nerve agents. Consequently, enzymes degrading OPs are of paramount interest, as they could be used as bioscavengers and biodecontaminants. Looking for a stable OPs catalyst, able to support industrial process constraints, a hyperthermophilic phosphotriesterase (PTE) (SsoPox) was isolated from the archaeon Sulfolobus solfataricus and was found to be highly thermostable. The solved 3D structure revealed that SsoPox is a noncovalent dimer, with lactonase activity against "quorum sensing signals", and therefore could represent also a potential weapon against certain pathogens. The structural basis of the high thermostability of SsoPox has been investigated by performing a careful comparison between its structure and that of two mesophilic PTEs from Pseudomonas diminuta and Agrobacterium radiobacter. In addition, the conformational stability of SsoPox against the denaturing action of temperature and GuHCl has been determined by means of circular dichroism and fluorescence measurements. The data suggest that the two fundamental differences between SsoPox and the mesophilic counterparts are: (a) a larger number of surface salt bridges, also involved in complex networks; (b) a tighter quaternary structure due to an optimization of the interactions at the interface between the two monomers.
authors.affiliation: Dipartimento di Chimica Paolo Corradini, Università di Napoli Federico II, Via Cintia, 80126, Naples, Italy.
authors.forename: Pompea
authors.initials: P
authors.lastname: Del Vecchio
authors.forename: Mikael
authors.initials: M
authors.lastname: Elias
authors.forename: Luigia
authors.initials: L
authors.lastname: Merone
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Graziano
authors.forename: Jérôme
authors.initials: J
authors.lastname: Dupuy
authors.forename: Luigi
authors.initials: L
authors.lastname: Mandrich
authors.forename: Paola
authors.initials: P
authors.lastname: Carullo
authors.forename: Bertrand
authors.initials: B
authors.lastname: Fournier
authors.forename: Daniel
authors.initials: D
authors.lastname: Rochu
authors.forename: Mosè
authors.initials: M
authors.lastname: Rossi
authors.forename: Patrick
authors.initials: P
authors.lastname: Masson
authors.forename: Eric
authors.initials: E
authors.lastname: Chabriere
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Manco
mesh_terms: D019843:Archaeal Proteins / Q000737:chemistry*; D002942:Circular Dichroism; D008958:Models, Molecular; D011487:Protein Conformation; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D055672:Static Electricity; D048229:Sulfolobus solfataricus / Q000737:chemistry*
chemical_list: D019843:Archaeal Proteins