Oligosaccharide Binding in Escherichia coli Glycogen Synthase

Journal Article · Wed Nov 17 04:00:00 EST 2010 · Biochemistry-US

DOI:https://doi.org/10.1021/bi900916t· OSTI ID:1006203

Sheng, Fang; Yep, Alejandra; Feng, Lei; Preiss, Jack; Geiger, James H

Glycogen/starch synthase elongates glucan chains and is the key enzyme in the synthesis of glycogen in bacteria and starch in plants. Cocrystallization of Escherichia coli wild-type glycogen synthase (GS) with substrate ADPGlc and the glucan acceptor mimic HEPPSO produced a closed form of GS and suggests that domain-domain closure accompanies glycogen synthesis. Cocrystallization of the inactive GS mutant E377A with substrate ADPGlc and oligosaccharide results in the first oligosaccharide-bound glycogen synthase structure. Four bound oligosaccharides are observed, one in the interdomain cleft (G6a) and three on the N-terminal domain surface (G6b, G6c, and G6d). 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 GS. The surface-bound oligosaccharides G6c and G6d have less interaction with enzyme and exhibit a more curled, helixlike structural arrangement. The observation that oligosaccharides bind only to the N-terminal domain of GS suggests that glycogen in vivo probably binds to only one side of the enzyme to ensure unencumbered interdomain movement, which is required for efficient, continuous glucan-chain synthesis.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: USDOE
• OSTI ID: 1006203
• Journal Information: Biochemistry-US, Journal Name: Biochemistry-US Journal Issue: (42) ; 10, 2009 Vol. 48; ISSN 0006-2960; ISSN BICHAW
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
99 GENERAL AND MISCELLANEOUS
BACTERIA
CHAINS
CLOSURES
ENZYMES
ESCHERICHIA COLI
GLYCOGEN
IN VIVO
LINERS
MUTANTS
OLIGOSACCHARIDES
RESIDUES
STARCH
SUBSTRATES
SYNTHESIS