PDBsum entry: 2bis

Transferase

PDB id: 2bis

Contents

Protein chains

440 a.a. *

Ligands

GLC ×2

DIO ×10

GOL ×7

UDP

* Residue conservation analysis

PDB id:

2bis

Name:

Transferase

Title:

Structure of glycogen synthase from pyrococcus abyssi

Structure:

Glga glycogen synthase. Chain: a, b, c. Engineered: yes

Source:

Pyrococcus abyssi. Organism_taxid: 29292. Expressed in: escherichia coli. Expression_system_taxid: 469008. Expression_system_variant: (de3)-ril.

Resolution:

2.80Å R-factor: 0.204 R-free: 0.266

Authors:

C.Horcajada,J.J.Guinovart,I.Fita,J.C.Ferrer

Key ref:

C.Horcajada et al. (2006). Crystal structure of an archaeal glycogen synthase: insights into oligomerization and substrate binding of eukaryotic glycogen synthases. J Biol Chem, 281, 2923-2931. PubMed id: 16319074 DOI: 10.1074/jbc.M507394200

Date:

25-Jan-05 Release date: 28-Nov-05

Protein chains

Q9V2J8  (Q9V2J8_PYRAB) -  GlgA glycogen synthase

Seq: 437 a.a.

Struc: 440 a.a.

 Gene Ontology (GO) functional annotation 

• Biological process: biosynthetic process (2 terms)
• Biochemical function: starch synthase activity (1 term)

DOI no: 10.1074/jbc.M507394200

J Biol Chem 281:2923-2931 (2006)

PubMed id: 16319074

Crystal structure of an archaeal glycogen synthase: insights into oligomerization and substrate binding of eukaryotic glycogen synthases.

C.Horcajada, J.J.Guinovart, I.Fita, J.C.Ferrer.

ABSTRACT

Glycogen and starch synthases are retaining glycosyltransferases that catalyze the transfer of glucosyl residues to the non-reducing end of a growing alpha-1,4-glucan chain, a central process of the carbon/energy metabolism present in almost all living organisms. The crystal structure of the glycogen synthase from Pyrococcus abyssi, the smallest known member of this family of enzymes, revealed that its subunits possess a fold common to other glycosyltransferases, a pair of beta/alpha/beta Rossmann fold-type domains with the catalytic site at their interface. Nevertheless, the archaeal enzyme presents an unprecedented homotrimeric molecular arrangement both in solution, as determined by analytical ultracentrifugation, and in the crystal. The C-domains are not involved in intersubunit interactions of the trimeric molecule, thus allowing for movements, likely required for catalysis, across the narrow hinge that connects the N- and C-domains. The radial disposition of the subunits confers on the molecule a distinct triangular shape, clearly visible with negative staining electron microscopy, in which the upper and lower faces present a sharp asymmetry. Comparison of bacterial and eukaryotic glycogen synthases, which use, respectively, ADP or UDP glucose as donor substrates, with the archaeal enzyme, which can utilize both molecules, allowed us to propose the residues that determine glucosyl donor specificity.

Selected figure(s)

Figure 3.
Oligomerization interactions. A, overall fold of PaGS (left panel) and AtGS (right panel) showing the distinct sequence elements responsible for the trimerization of PaGS (green) and dimerization of AtGS (red). B, stereographic view of the interaction of the C-terminal tail of one PaGS monomer (C atoms in green) with the complementary hydrophobic cavity of the neighboring subunit (C atoms in yellow). Atoms are shown red (O), blue (N). Only the first (Ile-429) and the last (Leu-437) amino acids of the C-terminal tail are labeled.

Figure 7.
Diagram representing the complex hydrogen bonding pattern involving His-151 of PaGS and a glucosyl residue at subsite -1 of the oligosaccharide substrate, modeled following the structure of the ternary complex of maltodextrin phosphorylase with maltohexaose and inorganic phosphate (27). Atoms are shown red (O), blue (N), purple (P), yellow (protein C), and green (oligosaccharide C).

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2006, 281, 2923-2931) copyright 2006.

Figures were selected by an automated process.