PMID:15033495
| Citation |
Yep, A, Ballicora, MA and Preiss, J (2004) The active site of the Escherichia coli glycogen synthase is similar to the active site of retaining GT-B glycosyltransferases. Biochem. Biophys. Res. Commun. 316:960-6 |
|---|---|
| Abstract |
Bacterial glycogen synthases transfer a glucosyl unit, retaining the anomeric configuration, from ADP-glucose to the non-reducing end of glycogen. We modeled the Escherichia coli glycogen synthase based on three glycosyltransferases with a GT-B fold. Comparison between the model and the structure of the active site of crystallized retaining GT-B glycosyltransferases identified conserved residues with the same topology. To confirm the importance of these residues predicted by the model, we studied them in E. coli glycogen synthase by site-directed mutagenesis. Mutations D137A, R300A, K305A, and H161A decreased the specific activity 8100-, 2600-, 1200-, and 710-fold, respectively. None of these mutations increased the Km for glycogen and only H161A and R300A had a higher Km for ADP-Glc of 11- and 8-fold, respectively. These residues were essential, validating the model that shows a strong similarity between the active site of E. coli glycogen synthase and the other retaining GT-B glycosyltransferases known to date. |
| Links |
PubMed Online version:10.1016/j.bbrc.2004.02.136 |
| Keywords |
Alanine/chemistry; Binding Sites; Crystallography, X-Ray; DNA Mutational Analysis; Escherichia coli/enzymology; Glycogen Synthase/chemistry; Glycosyltransferases/chemistry; Kinetics; Models, Molecular; Mutagenesis, Site-Directed; Mutation; Plasmids/metabolism; Protein Conformation; Protein Folding; Protein Structure, Secondary; Protein Structure, Tertiary |
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