Carbohydrate binding module recognition of xyloglucan defined by polar contacts with branching xyloses and CH-Π interactions.

Engineering of novel carbohydrate-binding proteins that can be utilized in various biochemical and biotechnical applications would benefit from a deeper understanding of the biochemical interactions that determine protein-carbohydrate specificity. In an effort to understand further the basis for specificity we present the crystal structure of the multi-specific carbohydrate-binding module (CBM) X-2 L110F bound to a branched oligomer of xyloglucan (XXXG). X-2 L110F is an engineered CBM that can recognize xyloglucan, xylans and β-glucans. The structural observations of the present study compared with previously reported structures of X-2 L110F in complex with linear oligomers, show that the π-surface of a phenylalanine, F110, allows for interactions with hydrogen atoms on both linear (xylopentaose and cellopentaose) and branched ligands (XXXG). Furthermore, X-2 L110F is shown to have a relatively flexible binding cleft, as illustrated in binding to XXXG. This branched ligand requires a set of reorientations of protein side chains Q72, N31, and R142, although these residues have previously been determined as important for binding to xylose oligomers by mediating polar contacts. The loss of these polar contacts is compensated for in binding to XXXG by polar interactions mediated by other protein residues, T74, R115, and Y149, which interact mainly with the branching xyloses of the xyloglucan oligomer. Taken together, the present study illustrates in structural detail how CH-π interactions can influence binding specificity and that flexibility is a key feature for the multi-specificity displayed by X-2 L110F, allowing for the accommodation of branched ligands.

von Schantz L ，Håkansson M ，Logan DT ，Nordberg-Karlsson E ，Ohlin M ... -  《-》

Structural basis for carbohydrate-binding specificity--a comparative assessment of two engineered carbohydrate-binding modules.

von Schantz L ，Håkansson M ，Logan DT ，Walse B ，Osterlin J ，Nordberg-Karlsson E ，Ohlin M ... -  《-》

Neutron crystallographic studies reveal hydrogen bond and water-mediated interactions between a carbohydrate-binding module and its bound carbohydrate ligand.

Fisher SZ ，von Schantz L ，Håkansson M ，Logan DT ，Ohlin M ... -  《-》

Crystallization, neutron data collection, initial structure refinement and analysis of a xyloglucan heptamer bound to an engineered carbohydrate-binding module from xylanase.

Ohlin M ，von Schantz L ，Schrader TE ，Ostermann A ，Logan DT ，Fisher SZ ... -  《Acta Crystallographica Section F-Structural Biology Communications》

Xyloglucan is recognized by carbohydrate-binding modules that interact with beta-glucan chains.

Najmudin S ，Guerreiro CI ，Carvalho AL ，Prates JA ，Correia MA ，Alves VD ，Ferreira LM ，Romão MJ ，Gilbert HJ ，Bolam DN ，Fontes CM ... -  《JOURNAL OF BIOLOGICAL CHEMISTRY》