title: Acidophilic adaptations in the structure of Acetobacter aceti N5-carboxyaminoimidazole ribonucleotide mutase (PurE).
abstract: The crystal structure of Acetobacter aceti PurE was determined to a resolution of 1.55 A and is compared with the known structures of the class I PurEs from a mesophile, Escherichia coli, and a thermophile, Thermotoga maritima. Analyses of the general factors that increase protein stability are examined as potential explanations for the acid stability of A. aceti PurE. Increased inter-subunit hydrogen bonding and an increased number of arginine-containing salt bridges appear to account for the bulk of the increased acid stability. A chain of histidines linking two active sites is discussed in the context of the proton transfers catalyzed by the enzyme.
authors.affiliation: Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Ethan C
authors.initials: EC
authors.lastname: Settembre
authors.forename: Johnathan R
authors.initials: JR
authors.lastname: Chittuluru
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Mill
authors.forename: T Joseph
authors.initials: TJ
authors.lastname: Kappock
authors.forename: Steven E
authors.initials: SE
authors.lastname: Ealick
mesh_terms: D000091:Acetobacter / Q000201:enzymology*; D000595:Amino Acid Sequence; D001120:Arginine / Q000737:chemistry; D001665:Binding Sites; D018360:Crystallography, X-Ray / Q000379:methods; D004926:Escherichia coli / Q000201:enzymology; D006639:Histidine / Q000737:chemistry; D006860:Hydrogen Bonding; D019751:Intramolecular Transferases / Q000096:biosynthesis / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017510:Protein Folding; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D011522:Protons; D017386:Sequence Homology, Amino Acid; D020124:Thermotoga maritima / Q000201:enzymology
chemical_list: D011522:Protons; D006639:Histidine; D001120:Arginine; D019751:Intramolecular Transferases; C498062:N(5)-carboxyaminoimidazole ribonucletide mutase