PMID:12603203
| Citation |
McMillen, L, Beacham, IR and Burns, DM (2003) Cobalt activation of Escherichia coli 5'-nucleotidase is due to zinc ion displacement at only one of two metal-ion-binding sites. Biochem. J. 372:625-30 |
|---|---|
| Abstract |
Escherichia coli 5'-nucleotidase activity is stimulated 30- to 50-fold in vitro by the addition of Co(2+). Seven residues from conserved sequence motifs implicated in the catalytic and metal-ion-binding sites of E. coli 5'-nucleotidase (Asp(41), His(43), Asp(84), His(117), Glu(118), His(217) and His(252)) were selected for modification using site-directed mutagenesis of the cloned ushA gene. On the basis of comparative studies between the resultant mutant proteins and the wild-type enzyme, a model is proposed for E. coli 5'-nucleotidase in which a Co(2+) ion may displace the Zn(2+) ion at only one of two metal-ion-binding sites; the other metal-ion-binding site retains the Zn(2+) ion already present. The studies reported herein suggest that displacement occurs at the metal-ion-binding site consisting of residues Asp(84), Asn(116), His(217) and His(252), leading to the observed increase in 5'-nucleotidase activity. |
| Links |
PubMed PMC1223400 Online version:10.1042/BJ20021800 |
| Keywords |
5'-Nucleotidase/metabolism; Amino Acid Substitution; Binding Sites; Catalysis; Cobalt/pharmacology; DNA Primers/chemistry; Enzyme Activation/drug effects; Escherichia coli/enzymology; Escherichia coli Proteins; Kinetics; Metals/analysis; Metals/metabolism; Models, Biological; Mutagenesis, Site-Directed; Phosphoric Diester Hydrolases/genetics; Phosphoric Diester Hydrolases/metabolism; Polymerase Chain Reaction; Structure-Activity Relationship; Zinc/metabolism |
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