2zq0

Crystal structure of SusB complexed with acarbose

spinqualitylabelsall models 2zq0, resolution 1.60Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2zq0 is a 2 chain structure with sequence from Bacteroides thetaiotaomicron. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: ACR, CA Related: 2d73 Gene: SusB, BT_3703 (Bacteroides thetaiotaomicron) Activity: Alpha-glucosidase, with EC number 3.2.1.20 Resources: FirstGlance, OCA, RCSB, PDBsum Function [P71094_BACTN] Glucoamylase that hydrolyzes alpha-1,4-glucosidic linkages, alpha-1,6-, alpha-1,3- and alpha-1,2-glucosidic linkages during starch degradation. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed SusB, an 84-kDa alpha-glucoside hydrolase involved in the starch utilization system (sus) of Bacteroides thetaiotaomicron, belongs to glycoside hydrolase (GH) family 97. We have determined the enzymatic characteristics and the crystal structures in free and acarbose-bound form at 1.6A resolution. SusB hydrolyzes the alpha-glucosidic linkage, with inversion of anomeric configuration liberating the beta-anomer of glucose as the reaction product. The substrate specificity of SusB, hydrolyzing not only alpha-1,4-glucosidic linkages but also alpha-1,6-, alpha-1,3-, and alpha-1,2-glucosidic linkages, is clearly different from other well known glucoamylases belonging to GH15. The structure of SusB was solved by the single-wavelength anomalous diffraction method with sulfur atoms as anomalous scatterers using an in-house x-ray source. SusB includes three domains as follows: the N-terminal, catalytic, and C-terminal domains. The structure of the SusB-acarbose complex shows a constellation of carboxyl groups at the catalytic center; Glu532 is positioned to provide protonic assistance to leaving group departure, with Glu439 and Glu508 both positioned to provide base-catalyzed assistance for inverting nucleophilic attack by water. A structural comparison with other glycoside hydrolases revealed significant similarity between the catalytic domain of SusB and those of alpha-retaining glycoside hydrolases belonging to GH27, -36, and -31 despite the differences in catalytic mechanism. SusB and the other retaining enzymes appear to have diverged from a common ancestor and individually acquired the functional carboxyl groups during the process of evolution. Furthermore, sequence comparison of the active site based on the structure of SusB indicated that GH97 included both retaining and inverting enzymes. Structural and functional analysis of a glycoside hydrolase family 97 enzyme from Bacteroides thetaiotaomicron.,Kitamura M, Okuyama M, Tanzawa F, Mori H, Kitago Y, Watanabe N, Kimura A, Tanaka I, Yao M J Biol Chem. 2008 Dec 26;283(52):36328-37. Epub 2008 Nov 3. PMID:18981178 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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