8HJ6
Crystal structure of barley exohydrolase isoform ExoI E220A mutant
Summary for 8HJ6
| Entry DOI | 10.2210/pdb8hj6/pdb |
| Descriptor | Glyco_hydro_3 domain-containing protein, 2-acetamido-2-deoxy-beta-D-glucopyranose, PENTAETHYLENE GLYCOL, ... (7 entities in total) |
| Functional Keywords | barley exohydrolasei, hydrolase, enzyme function |
| Biological source | Hordeum vulgare |
| Total number of polymer chains | 1 |
| Total formula weight | 68444.40 |
| Authors | Luang, S.,Streltsov, V.A.,Hrmova, M. (deposition date: 2022-11-22, release date: 2024-12-25, Last modification date: 2025-05-21) |
| Primary citation | Luang, S.,Fernandez-Luengo, X.,Streltsov, V.A.,Marechal, J.D.,Masgrau, L.,Hrmova, M. The structure and dynamics of water molecule networks underlie catalytic efficiency in a glycoside exo-hydrolase. Commun Biol, 8:729-729, 2025 Cited by PubMed Abstract: Glycoside hydrolases break glycosidic bonds by transferring a water molecule onto the glycosidic oxygen of carbohydrates, but on the nanoscale, the dynamics of water molecules remains unclear. We investigate the role of the non-nucleophilic E220 glutamate, essential for maintaining the water molecule network in a family 3 β-D-glucan glucohydrolase, but not involved directly in catalysis. Kinetic data disclose that the E220A mutant retains substrate poly-specificity but has drastically reduced catalytic efficiency compared to the wild-type. High-resolution structures in-complex with a hydrolytic product and a mechanism-based inhibitor reveal that in wild-type, the concatenated water molecules near acid/base E491 and neighbouring N219 and E220 form a harmonised network. In contrast, in the E220A mutant, this network is uncoordinated. Computational models of covalent complexes show that water flux through the wild-type protein correlates with high catalytic efficiency dissimilar to E220A, where this correlation is lost. Ancestral sequence reconstructions of family 3 enzymes divulge the evolutionary conservation of residues participating in water molecule networks, which underlie substrate-product-assisted processivity. Our findings provide a blueprint for the dynamics of catalysis mediated by hydrolytic enzymes, which could inspire bioengineering to create a sustainable bio-economy. PubMed: 40348901DOI: 10.1038/s42003-025-08113-9 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (1.79 Å) |
Structure validation
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