PMID:19244233
| Citation |
Sheng, F, Jia, X, Yep, A, Preiss, J and Geiger, JH (2009) The crystal structures of the open and catalytically competent closed conformation of Escherichia coli glycogen synthase. J. Biol. Chem. 284:17796-807 |
|---|---|
| Abstract |
Escherichia coli glycogen synthase (EcGS, EC 2.4.1.21) is a retaining glycosyltransferase (GT) that transfers glucose from adenosine diphosphate glucose to a glucan chain acceptor with retention of configuration at the anomeric carbon. EcGS belongs to the GT-B structural superfamily. Here we report several EcGS x-ray structures that together shed considerable light on the structure and function of these enzymes. The structure of the wild-type enzyme bound to ADP and glucose revealed a 15.2 degrees overall domain-domain closure and provided for the first time the structure of the catalytically active, closed conformation of a glycogen synthase. The main chain carbonyl group of His-161, Arg-300, and Lys-305 are suggested by the structure to act as critical catalytic residues in the transglycosylation. Glu-377, previously thought to be catalytic is found on the alpha-face of the glucose and plays an electrostatic role in the active site and as a glucose ring locator. This is also consistent with the structure of the EcGS(E377A)-ADP-HEPPSO complex where the glucose moiety is either absent or disordered in the active site. |
| Links |
PubMed PMC2719418 Online version:10.1074/jbc.M809804200 |
| Keywords |
Adenosine Diphosphate Glucose/metabolism; Binding Sites; Crystallography, X-Ray; Escherichia coli/enzymology; Glycogen Synthase/chemistry; Glycogen Synthase/metabolism; Models, Molecular; Protein Binding; Protein Structure, Tertiary |
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