1uy2

Binding sub-site dissection of a family 6 carbohydrate-binding module by X-ray crystallography and isothermal titration calorimetry

spinqualitylabelsall models 1uy2, resolution 1.70Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1uy2 is a 1 chain structure with sequence from Thermoclostridium stercorarium. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.7Å Ligands: CA, GOL, NA, PRD_900116, XYP Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function XYNA1_THEST Endoxylanase that degrades arabinoxylan and glucuronoxylan to xylobiose and xylotriose (in vitro). 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 The optimal ligands for many carbohydrate-binding proteins are often oligosaccharides comprising two, three, or more monosaccharide units. The binding affinity for these sugars is increased incrementally by contributions from binding subsites on the protein that accommodate the individual monosaccharide residues of the oligosaccharide. Here, we use CsCBM6-1, a xylan-specific type B carbohydrate-binding module (CBM) from Clostridium stercorarium falling into amino acid sequence family CBM6, as a model system to investigate the structural and thermodynamic contributions of binding subsites in this protein to carbohydrate recognition. The three-dimensional structures of uncomplexed CsCBM6-1 (at 1.8 A resolution) and bound to the oligosaccharides xylobiose, xylotriose, and xylotetraose (at 1.70 A, 1.89 A, and 1.69 A resolution, respectively) revealed the sequential occupation of four subsites within the binding site in the order of subsites 2, 3, 4 then 1. Overall, binding to all of the xylooligosaccharides tested was enthalpically favourable and entropically unfavourable, like most protein-carbohydrate interactions, with the primary subsites 2 and 3 providing the bulk of the free energy and enthalpy of binding. In contrast, the contributions to the changes in entropy of the non-primary subsites 1 and 4 to xylotriose and xylotetraose binding, respectively, were positive. This observation is remarkable, in that it shows that the 10-20-fold improvement in association constants for oligosaccharides longer than a disaccharide is facilitated by favourable entropic contributions from the non-primary binding subsites. Binding sub-site dissection of a carbohydrate-binding module reveals the contribution of entropy to oligosaccharide recognition at "non-primary" binding subsites.,Lammerts van Bueren A, Boraston AB J Mol Biol. 2004 Jul 16;340(4):869-79. PMID:15223327 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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