1E5C

Internal xylan binding domain from C. fimi Xyn10A, R262G mutant

1E5C の概要

• エントリーDOI: 10.2210/pdb1e5c/pdb
• 関連するPDBエントリー: 1E5B 1XBD 2XBD
• NMR情報: BMRB: 4623
• 分子名称: XYLANASE D (1 entity in total)
• 機能のキーワード: hydrolase, xylan binding domain, xylanase, beta-sheet
• 由来する生物種: CELLULOMONAS FIMI
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 8687.27

構造登録者

Simpson, P.J.,Hefang, X.,Bolam, D.N.,Gilbert, H.J.,Williamson, M.P. (登録日: 2000-07-24, 公開日: 2001-05-25, 最終更新日: 2024-11-13)

主引用文献

Simpson, P.J.,Hefang, X.,Bolam, D.N.,Gilbert, H.J.,Williamson, M.P.
The Structural Basis for the Ligand Specificity of Family 2 Carbohydrate Binding Nodules
J.Biol.Chem., 275:41137-, 2000

PubMed Abstract: 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.

PubMed: 10973978
DOI: 10.1074/JBC.M006948200

実験手法

SOLUTION NMR