5H4R
the complex of Glycoside Hydrolase 5 Lichenase from Caldicellulosiruptor sp. F32 E188Q mutant and cellotetraose
Summary for 5H4R
| Entry DOI | 10.2210/pdb5h4r/pdb |
| Related | 4X0V |
| Related PRD ID | PRD_900011 |
| Descriptor | Beta-1,3-1,4-glucanase, beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose, GLYCEROL, ... (4 entities in total) |
| Functional Keywords | glycoside hydrolase 5 lichenase, hydrolase |
| Biological source | Caldicellulosiruptor sp. F32 |
| Total number of polymer chains | 1 |
| Total formula weight | 46640.73 |
| Authors | |
| Primary citation | Meng, D.D.,Liu, X.,Dong, S.,Wang, Y.F.,Ma, X.Q.,Zhou, H.,Wang, X.,Yao, L.S.,Feng, Y.,Li, F.L. Structural insights into the substrate specificity of a glycoside hydrolase family 5 lichenase from Caldicellulosiruptor sp. F32 Biochem. J., 474:3373-3389, 2017 Cited by PubMed Abstract: Glycoside hydrolase (GH) family 5 is one of the largest GH families with various GH activities including lichenase, but the structural basis of the GH5 lichenase activity is still unknown. A novel thermostable lichenase F32EG5 belonging to GH5 was identified from an extremely thermophilic bacterium sp. F32. F32EG5 is a bi-functional cellulose and a lichenan-degrading enzyme, and exhibited a high activity on β-1,3-1,4-glucan but side activity on cellulose. Thin-layer chromatography and NMR analyses indicated that F32EG5 cleaved the β-1,4 linkage or the β-1,3 linkage while a 4--substitued glucose residue linked to a glucose residue through a β-1,3 linkage, which is completely different from extensively studied GH16 lichenase that catalyses strict endo-hydrolysis of the β-1,4-glycosidic linkage adjacent to a 3--substitued glucose residue in the mixed-linked β-glucans. The crystal structure of F32EG5 was determined to 2.8 Å resolution, and the crystal structure of the complex of F32EG5 E193Q mutant and cellotetraose was determined to 1.7 Å resolution, which revealed that the exit subsites of substrate-binding sites contribute to both thermostability and substrate specificity of F32EG5. The sugar chain showed a sharp bend in the complex structure, suggesting that a substrate cleft fitting to the bent sugar chains in lichenan is a common feature of GH5 lichenases. The mechanism of thermostability and substrate selectivity of F32EG5 was further demonstrated by molecular dynamics simulation and site-directed mutagenesis. These results provide biochemical and structural insights into thermostability and substrate selectivity of GH5 lichenases, which have potential in industrial processes. PubMed: 28838949DOI: 10.1042/BCJ20170328 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (1.70310440144 Å) |
Structure validation
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