Acidophilic adaptations in the structure of Acetobacter aceti N5-carboxyaminoimidazole ribonucleotide mutase (PurE).
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.
Settembre
Ethan C
EC
Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA.
Chittuluru
Johnathan R
JR
Mill
Christopher P
CP
Kappock
T Joseph
TJ
Ealick
Steven E
SE
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
D011522:Protons; D006639:Histidine; D001120:Arginine; D019751:Intramolecular Transferases; C498062:N(5)-carboxyaminoimidazole ribonucletide mutase