Structural determinants of the high thermal stability of SsoPox from the hyperthermophilic archaeon Sulfolobus solfataricus.
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.
Del Vecchio
Pompea
P
Dipartimento di Chimica Paolo Corradini, Università di Napoli Federico II, Via Cintia, 80126, Naples, Italy.
Elias
Mikael
M
Merone
Luigia
L
Graziano
Giuseppe
G
Dupuy
Jérôme
J
Mandrich
Luigi
L
Carullo
Paola
P
Fournier
Bertrand
B
Rochu
Daniel
D
Rossi
Mosè
M
Masson
Patrick
P
Chabriere
Eric
E
Manco
Giuseppe
G
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*
D019843:Archaeal Proteins