1OH3

E78R mutant of a carbohydrate binding module family 29

1OH3 の概要

• エントリーDOI: 10.2210/pdb1oh3/pdb
• 関連するPDBエントリー: 1GWK 1GWL 1GWM
• 分子名称: NON-CATALYTIC PROTEIN 1, beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-alpha-D-glucopyranose (3 entities in total)
• 機能のキーワード: carbohydrate binding domain, glucomannan, cellohexaose, mannohexaose, cellulosome, ncp1
• 由来する生物種: PIROMYCES EQUI
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 33114.38

構造登録者

Nurizzo, D.,Gilbert, H.J.,Davies, G.J. (登録日: 2003-05-21, 公開日: 2004-05-27, 最終更新日: 2023-12-13)

主引用文献

Flint, J.,Nurizzo, D.,Harding, S.E.,Longman, E.,Davies, G.J.,Gilbert, H.J.,Bolam, D.N.
Ligand-Mediated Dimerization of a Carbohydrate -Binding Module Reveals a Novel Mechanism for Protein-Carbohydrate Recognition
J.Mol.Biol., 337:417-, 2004

PubMed Abstract: The structural and thermodynamic basis for carbohydrate-protein recognition is of considerable importance. NCP-1, which is a component of the Piromyces equi cellulase/hemicellulase complex, presents a provocative model for analyzing how structural and mutational changes can influence the ligand specificity of carbohydrate-binding proteins. NCP-1 contains two "family 29" carbohydrate-binding modules designated CBM29-1 and CBM29-2, respectively, that display unusually broad specificity; the proteins interact weakly with xylan, exhibit moderate affinity for cellulose and mannan, and bind tightly to the beta-1,4-linked glucose-mannose heteropolymer glucomannan. The crystal structure of CBM29-2 in complex with cellohexaose and mannohexaose identified key residues involved in ligand recognition. By exploiting this structural information and the broad specificity of CBM29-2, we have used this protein as a template to explore the evolutionary mechanisms that can lead to significant changes in ligand specificity. Here, we report the properties of the E78R mutant of CBM29-2, which displays ligand specificity that is different from that of wild-type CBM29-2; the protein retains significant affinity for cellulose but does not bind to mannan or glucomannan. Significantly, E78R exhibits a stoichiometry of 0.5 when binding to cellohexaose, and both calorimetry and ultracentrifugation show that the mutant protein displays ligand-mediated dimerization in solution. The three-dimensional structure of E78R in complex with cellohexaose reveals the intriguing molecular basis for this "dimeric" binding mode that involves the lamination of the oligosaccharide between two CBM molecules. The 2-fold screw axis of the ligand is mirrored in the orientation of the two protein domains with adjacent sugar rings stacking against the equivalent aromatic residues in the binding site of each protein molecule of the molecular sandwich. The sandwiching of an oligosaccharide chain between two protein modules, leading to ligand-induced formation of the binding site, represents a completely novel mechanism for protein-carbohydrate recognition that may mimic that displayed by naturally dimeric protein-carbohydrate interactions.

PubMed: 15003456
DOI: 10.1016/J.JMB.2003.12.081

実験手法

X-RAY DIFFRACTION (1.5 Å)