3rsz | pdb_00003rsz

Maltodextran bound basal state conformation of yeast glycogen synthase isoform 2

spinqualitylabelsall models 3rsz, resolution 3.01Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3rsz is a 6 chain structure with sequence from Atcc 18824. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: GLC, SO4 NonStd Res: UNK Related: 3naz, 3nch, 3o3c Gene: GSY2, L8479.8, YLR258W (ATCC 18824) Activity: Glycogen(starch) synthase, with EC number 2.4.1.11 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [GYS2_YEAST] Transfers the glycosyl residue from UDP-Glc to the non-reducing end of alpha-1,4-glucan. Is believed to regulate the synthesis of glycogen. Publication Abstract from PubMed Glycogen synthase is a rate-limiting enzyme in the biosynthesis of glycogen and has an essential role in glucose homeostasis. The three-dimensional structures of yeast glycogen synthase (Gsy2p) complexed with maltooctaose identified four conserved maltodextrin-binding sites distributed across the surface of the enzyme. Site-1 is positioned on the N-terminal domain, site-2 and site-3 are present on the C-terminal domain, and site-4 is located in an interdomain cleft adjacent to the active site. Mutation of these surface sites decreased glycogen binding and catalytic efficiency toward glycogen. Mutations within site-1 and site-2 reduced the V(max)/S(0.5) for glycogen by 40- and 70-fold, respectively. Combined mutation of site-1 and site-2 decreased the V(max)/S(0.5) for glycogen by >3000-fold. Consistent with the in vitro data, glycogen accumulation in glycogen synthase-deficient yeast cells (Deltagsy1-gsy2) transformed with the site-1, site-2, combined site-1/site-2, or site-4 mutant form of Gsy2p was decreased by up to 40-fold. In contrast to the glycogen results, the ability to utilize maltooctaose as an in vitro substrate was unaffected in the site-2 mutant, moderately affected in the site-1 mutant, and almost completely abolished in the site-4 mutant. These data show that the ability to utilize maltooctaose as a substrate can be independent of the ability to utilize glycogen. Our data support the hypothesis that site-1 and site-2 provide a "toehold mechanism," keeping glycogen synthase tightly associated with the glycogen particle, whereas site-4 is more closely associated with positioning of the nonreducing end during catalysis. Multiple Glycogen-binding Sites in Eukaryotic Glycogen Synthase Are Required for High Catalytic Efficiency toward Glycogen.,Baskaran S, Chikwana VM, Contreras CJ, Davis KD, Wilson WA, Depaoli-Roach AA, Roach PJ, Hurley TD J Biol Chem. 2011 Sep 30;286(39):33999-4006. Epub 2011 Aug 11. PMID:21835915 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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