1l2a | pdb_00001l2a

The Crystal Structure and Catalytic Mechanism of Cellobiohydrolase CelS, the Major Enzymatic Component of the Clostridium thermocellum cellulosome

spinqualitylabelsall models 1l2a, resolution 2.50Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1l2a is a 6 chain structure with sequence from Atcc 27405. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: BGC Related: 1l1y Gene: cels (ATCC 27405) Activity: Cellulase, with EC number 3.2.1.4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [GUNS_CLOTM] This enzyme catalyzes the endohydrolysis of 1,4-beta-glucosidic linkages in cellulose, lichenin and cereal beta-D-glucans. 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 Cellobiohydrolase CelS plays an important role in the cellulosome, an active cellulase system produced by the thermophilic anaerobe Clostridium thermocellum. The structures of the catalytic domain of CelS in complex with substrate (cellohexaose) and product (cellobiose) were determined at 2.5 and 2.4 A resolution, respectively. The protein folds into an (alpha/alpha)(6) barrel with a tunnel-shaped substrate-binding region. The conformation of the loops defining the tunnel is intrinsically stable in the absence of substrate, suggesting a model to account for the processive mode of action of family 48 cellobiohydrolases. Structural comparisons with other (alpha/alpha)(6) barrel glycosidases indicate that CelS and endoglucanase CelA, a sequence-unrelated family 8 glycosidase with a groove-shaped substrate-binding region, use the same catalytic machinery to hydrolyze the glycosidic linkage, despite a low sequence similarity and a different endo/exo mode of action. A remarkable feature of the mechanism is the absence, from CelS, of a carboxylic group acting as the base catalyst. The nearly identical arrangement of substrate and functionally important residues in the two active sites strongly suggests an evolutionary relationship between the cellobiohydrolase and endoglucanase families, which can therefore be classified into a new clan of glycoside hydrolases. The crystal structure and catalytic mechanism of cellobiohydrolase CelS, the major enzymatic component of the Clostridium thermocellum Cellulosome.,Guimaraes BG, Souchon H, Lytle BL, David Wu JH, Alzari PM J Mol Biol. 2002 Jul 12;320(3):587-96. PMID:12096911 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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