cocrystallization of the inactive glycogen synthase mutant E377A with substrate ADPGlc and cocrystallization of wild-type glycogen synthase with substrate ADPGlc and the glucan acceptor mimic 4-(2-hydroxyethyl)piperazine-1-(2-hydroxypropane)sulfonic acid, i.e. HEPPSO produces a closed form of glycogen synthase and suggests that domain-domain closure accompanies glycogen synthesis. Four bound oligosaccharides are observed, G6a in the interdomain cleft and G6b, G6c, and G6d on the N-terminal domain surface. Extending from the center of the enzyme to the interdomain cleft opening, G6a mostly interacts with the highly conserved N-terminal domain residues lining the cleft of glycogen synthase. The surface-bound oligosaccharides G6c and G6d have less interaction with enzyme and exhibit a more curled, helixlike structural arrangement |
Escherichia coli |