1dyo

Xylan-Binding Domain from CBM 22, formally x6b domain

spinqualitylabelsall models 1dyo, resolution 2.10Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1dyo is a 2 chain structure with sequence from Acetivibrio thermocellus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.1Å Ligands: CA, MSE Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function XYNY_ACETH 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 Many polysaccharide-degrading enzymes display a modular structure in which a catalytic module is attached to one or more noncatalytic modules. Several xylanases contain a module of previously unknown function (termed "X6" modules) that had been implicated in thermostability. We have investigated the properties of two such "thermostabilizing" modules, X6a and X6b from the Clostridium thermocellumxylanase Xyn10B. These modules, expressed either as discrete entities or as their natural fusions with the catalytic module, were assayed, and their capacity to bind various carbohydrates and potentiate hydrolytic activity was determined. The data showed that X6b, but not X6a, increased the activity of the enzyme against insoluble xylan and bound specifically to xylooligosaccharides and various xylans. In contrast, X6a exhibited no affinity for soluble or insoluble forms of xylan. Isothermal titration calorimetry revealed that the ligand-binding site of X6b accommodates approximately four xylose residues. The protein exhibited K(d) values in the low micromolar range for xylotetraose, xylopentaose, and xylohexaose; 24 microM for xylotriose; and 50 microM for xylobiose. Negative DeltaH and DeltaS values indicate that the interaction of X6b with xylooligosaccharides and xylan is driven by enthalpic forces. The three-dimensional structure of X6b has been solved by X-ray crystallography to a resolution of 2.1 A. The protein is a beta-sandwich that presents a tryptophan and two tyrosine residues on the walls of a shallow cleft that is likely to be the xylan-binding site. In view of the structural and carbohydrate-binding properties of X6b, it is proposed that this and related modules be re-assigned as family 22 carbohydrate-binding modules. The X6 "thermostabilizing" domains of xylanases are carbohydrate-binding modules: structure and biochemistry of the Clostridium thermocellum X6b domain.,Charnock SJ, Bolam DN, Turkenburg JP, Gilbert HJ, Ferreira LM, Davies GJ, Fontes CM Biochemistry. 2000 May 2;39(17):5013-21. PMID:10819965 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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