1e5c | pdb_00001e5c

INTERNAL XYLAN BINDING DOMAIN FROM C. FIMI XYN10A, R262G MUTANT

spinqualitylabelsall models 1e5c, 5 NMR models Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1e5c is a 1 chain structure with sequence from Cellulomonas fimi. Full experimental information is available from OCA. For a guided tour on the structure components use FirstGlance. Related: 2xbd, 1xbd, 1e5b Activity: Endo-1,4-beta-xylanase, with EC number 3.2.1.8 Resources: FirstGlance, OCA, RCSB, PDBsum 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 interactions of proteins with polysaccharides play a key role in the microbial hydrolysis of cellulose and xylan, the most abundant organic molecules in the biosphere, and are thus pivotal to the recycling of photosynthetically fixed carbon. Enzymes that attack these recalcitrant polymers have a modular structure comprising catalytic modules and non-catalytic carbohydrate-binding modules (CBMs). The largest prokaryotic CBM family, CBM2, contains members that bind cellulose (CBM2a) and xylan (CBM2b), respectively. A possible explanation for the different ligand specificity of CBM2b is that one of the surface tryptophans involved in the protein-carbohydrate interaction is rotated by 90 degrees compared with its position in CBM2a (thus matching the structure of the binding site to the helical secondary structure of xylan), which may be promoted by a single amino acid difference between the two families. Here we show that by mutation of this single residue (Arg-262-->Gly), a CBM2b xylan-binding module completely loses its affinity for xylan and becomes a cellulose-binding module. The structural effect of the mutation has been revealed using NMR spectroscopy, which confirms that Trp-259 rotates 90 degrees to lie flat against the protein surface. Except for this one residue, the mutation only results in minor changes to the structure. The mutated protein interacts with cellulose using the same residues that the wild-type CBM2b uses to interact with xylan, suggesting that the recognition is of the secondary structure of the polysaccharide rather than any specific recognition of the absence or presence of functional groups. The structural basis for the ligand specificity of family 2 carbohydrate-binding modules.,Simpson PJ, Xie H, Bolam DN, Gilbert HJ, Williamson MP J Biol Chem. 2000 Dec 29;275(52):41137-42. PMID:10973978 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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