title: X-ray structure of the first `extremo-α-carbonic anhydrase', a dimeric enzyme from the thermophilic bacterium Sulfurihydrogenibium yellowstonense YO3AOP1.
abstract: SspCA, a novel `extremo-α-carbonic anhydrase' isolated from the thermophilic bacterium Sulfurihydrogenibium yellowstonense YO3AOP1, is an efficient catalyst for the hydration of CO2 and presents exceptional thermostability. Indeed, SspCA retains a high catalytic activity even after being heated to 343-373 K for several hours. Here, the crystallographic structure of this α-carbonic anhydrase (α-CA) is reported and the factors responsible for its function at high temperature are elucidated. In particular, the study suggests that increased structural compactness, together with an increased number of charged residues on the protein surface and a greater number of ionic networks, seem to be the key factors involved in the higher thermostability of this enzyme with respect to its mesophilic homologues. These findings are of extreme importance, since they provide a structural basis for the understanding of the mechanisms responsible for thermal stability in the α-CA family for the first time. The data obtained offer a tool that can be exploited to engineer α-CAs in order to obtain enzymes with enhanced thermostability for use in the harsh conditions of the CO2 capture and sequestration processes.
authors.affiliation: Istituto di Biostrutture e Bioimmagini - CNR, Via Mezzocannone 16, 80134 Napoli, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Di Fiore
authors.forename: Clemente
authors.initials: C
authors.lastname: Capasso
authors.forename: Viviana
authors.initials: V
authors.lastname: De Luca
authors.forename: Simona Maria
authors.initials: SM
authors.lastname: Monti
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Carginale
authors.forename: Claudiu T
authors.initials: CT
authors.lastname: Supuran
authors.forename: Andrea
authors.initials: A
authors.lastname: Scozzafava
authors.forename: Carlo
authors.initials: C
authors.lastname: Pedone
authors.forename: Mosè
authors.initials: M
authors.lastname: Rossi
authors.forename: Giuseppina
authors.initials: G
authors.lastname: De Simone
mesh_terms: D001105:Archaea / Q000201:enzymology* / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism*; D002256:Carbonic Anhydrases / Q000737:chemistry* / Q000378:metabolism; D002384:Catalysis; D002942:Circular Dichroism; D018360:Crystallography, X-Ray; D007700:Kinetics; D008958:Models, Molecular
chemical_list: D002245:Carbon Dioxide; D002256:Carbonic Anhydrases
keywords: Sulfurihydrogenibium yellowstonense YO3AOP1; thermostability; α-carbonic anhydrases