3wnn

D308A mutant of Bacillus circulans T-3040 cycloisomaltooligosaccharide glucanotransferase complexed with isomaltooctaose

spinqualitylabelsall models 3wnn, resolution 2.25Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3wnn is a 2 chain structure with sequence from Niallia circulans. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.25Å Ligands: BGC, CA, GLC, MES, NA, SO4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function CTA1_NIACI Produces cycloisomaltooligosaccharide from dextran containing 7, 8 or 9 glucose units. The enzyme is specific for (1->6)-alpha-D-glucans (dextrans) and, without activity toward (1->4)-alpha-D-glucans, such as amylose. It also has no activity on oligosaccharides, such as amylopectin and pullulan, containing (1->6)-alpha-D-glucosidic linkages at branch points. Publication Abstract from PubMed Bacillus circulans T-3040 cycloisomaltooligosaccharide glucanotransferase belongs to the glycoside hydrolase family 66 and catalyzes an intramolecular transglucosylation reaction that produces cycloisomaltooligosaccharides from dextran. The crystal structure of the core fragment from Ser-39 to Met-738 of B. circulans T-3040 cycloisomaltooligosaccharide glucanotransferase, devoid of its N-terminal signal peptide and C-terminal nonconserved regions, was determined. The structural model contained one catalytic (beta/alpha)8-barrel domain and three beta-domains. Domain N with an immunoglobulin-like beta-sandwich fold was attached to the N terminus; domain C with a Greek key beta-sandwich fold was located at the C terminus, and a carbohydrate-binding module family 35 (CBM35) beta-jellyroll domain B was inserted between the 7th beta-strand and the 7th alpha-helix of the catalytic domain A. The structures of the inactive catalytic nucleophile mutant enzyme complexed with isomaltohexaose, isomaltoheptaose, isomaltooctaose, and cycloisomaltooctaose revealed that the ligands bound in the catalytic cleft and the sugar-binding site of CBM35. Of these, isomaltooctaose bound in the catalytic site extended to the second sugar-binding site of CBM35, which acted as subsite -8, representing the enzyme.substrate complex when the enzyme produces cycloisomaltooctaose. The isomaltoheptaose and cycloisomaltooctaose bound in the catalytic cleft with a circular structure around Met-310, representing the enzyme.product complex. These structures collectively indicated that CBM35 functions in determining the size of the product, causing the predominant production of cycloisomaltooctaose by the enzyme. The canonical sugar-binding site of CBM35 bound the mid-part of isomaltooligosaccharides, indicating that the original function involved substrate binding required for efficient catalysis. Structural elucidation of the cyclization mechanism of alpha-1,6-glucan by Bacillus circulans T-3040 cycloisomaltooligosaccharide glucanotransferase.,Suzuki N, Fujimoto Z, Kim YM, Momma M, Kishine N, Suzuki R, Suzuki S, Kitamura S, Kobayashi M, Kimura A, Funane K J Biol Chem. 2014 Apr 25;289(17):12040-51. doi: 10.1074/jbc.M114.547992. Epub, 2014 Mar 10. PMID:24616103 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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