title: A comparative infrared spectroscopic study of glycoside hydrolases from extremophilic archaea revealed different molecular mechanisms of adaptation to high temperatures.
abstract: The identification of the determinants of protein thermal stabilization is often pursued by comparing enzymes from hyperthermophiles with their mesophilic counterparts while direct structural comparisons among proteins and enzymes from hyperthermophiles are rather uncommon. Here, oligomeric beta-glycosidases from the hyperthermophilic archaea Sulfolobus solfataricus (Ss beta-gly), Thermosphaera aggregans (Ta beta-gly), and Pyrococcus furiosus (Pf beta-gly), have been compared. Studies of FTIR spectroscopy and kinetics of thermal inactivation showed that the three enzymes had similar secondary structure composition, but Ss beta-gly and Ta beta-gly (temperatures of melting 98.1 and 98.4 degrees C, respectively) were less stable than Pf beta-gly, which maintained its secondary structure even at 99.5 degrees C. The thermal denaturation of Pf beta-gly, followed in the presence of SDS, suggested that this enzyme is stabilized by hydrophobic interactions. A detailed inspection of the 3D-structures of these enzymes supported the experimental results: Ss beta-gly and Ta beta-gly are stabilized by a combination of ion-pairs networks and intrasubunit S-S bridges while the increased stability of Pf beta-gly resides in a more compact protein core. The different strategies of protein stabilization give experimental support to recent theories on thermophilic adaptation and suggest that different stabilization strategies could have been adopted among archaea.
authors.affiliation: Institute of Biochemistry, Università Politecnica delle Marche, Via Ranieri, 60131 Ancona, Italy.
authors.forename: Alessio
authors.initials: A
authors.lastname: Ausili
authors.forename: Beatrice
authors.initials: B
authors.lastname: Cobucci-Ponzano
authors.forename: Barbara
authors.initials: B
authors.lastname: Di Lauro
authors.forename: Rossana
authors.initials: R
authors.lastname: D'Avino
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Perugino
authors.forename: Enrico
authors.initials: E
authors.lastname: Bertoli
authors.forename: Andrea
authors.initials: A
authors.lastname: Scirè
authors.forename: Mosè
authors.initials: M
authors.lastname: Rossi
authors.forename: Fabio
authors.initials: F
authors.lastname: Tanfani
authors.forename: Marco
authors.initials: M
authors.lastname: Moracci
mesh_terms: D000220:Adaptation, Biological; D019295:Computational Biology; D019620:Desulfurococcaceae / Q000201:enzymology*; D006026:Glycoside Hydrolases / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D011489:Protein Denaturation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D020027:Pyrococcus furiosus / Q000201:enzymology*; D013055:Spectrophotometry, Infrared; D048229:Sulfolobus solfataricus / Q000201:enzymology*; D013696:Temperature
chemical_list: D006026:Glycoside Hydrolases