title: Crystal structure and structural stability of acylphosphatase from hyperthermophilic archaeon Pyrococcus horikoshii OT3.
abstract: To elucidate the structural basis for the high stability of acylphosphatase (AcP) from Pyrococcus horikoshii OT3, we determined its crystal structure at 1.72 A resolution. P. horikoshii AcP possesses high stability despite its approximately 30% sequence identity with eukaryotic enzymes that have moderate thermostability. The overall fold of P. horikoshii AcP was very similar to the structures of eukaryotic counterparts. The crystal structure of P. horikoshii AcP shows the same fold betaalphabetabetaalphabeta topology and the conserved putative catalytic residues as observed in eukaryotic enzymes. Comparison with the crystal structure of bovine common-type AcP and that of D. melanogaster AcP (AcPDro2) as representative of eukaryotic AcP revealed some significant characteristics in P. horikoshii AcP that likely play important roles in structural stability: (1) shortening of the flexible N-terminal region and long loop; (2) an increased number of ion pairs on the protein surface; (3) stabilization of the loop structure by hydrogen bonds. In P. horikoshii AcP, two ion pair networks were observed one located in the loop structure positioned near the C-terminus, and other on the beta-sheet. The importance of ion pairs for structural stability was confirmed by site-directed mutation and denaturation induced by guanidium chloride.
authors.affiliation: Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Japan.
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Miyazono
authors.forename: Yoriko
authors.initials: Y
authors.lastname: Sawano
authors.forename: Masaru
authors.initials: M
authors.lastname: Tanokura
mesh_terms: D017766:Acid Anhydride Hydrolases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002417:Cattle; D017124:Conserved Sequence; D018360:Crystallography, X-Ray; D004331:Drosophila melanogaster; D004795:Enzyme Stability / Q000187:drug effects; D019791:Guanidine / Q000494:pharmacology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011188:Potassium / Q000737:chemistry; D011489:Protein Denaturation / Q000187:drug effects; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D043902:Pyrococcus horikoshii / Q000201:enzymology* / Q000235:genetics; D016415:Sequence Alignment; D000097024:Acylphosphatase
chemical_list: D017766:Acid Anhydride Hydrolases; D019791:Guanidine; D011188:Potassium; D000097024:Acylphosphatase