Crystal Structures of the Catalytic Domain of a Novel Glycohydrolase Family 23 Chitinase from Ralstonia sp. A-471 Reveals a Unique Arrangement of the Catalytic Residues for Inverting Chitin Hydrolysis
| Autor: | Mitsuhiro Ueda, Shoko Shinya, Taro Tamada, Kazutaka Miyatake, Masami Nakazawa, Noriko Kawamoto, Tamo Fukamizo, Takao Arimori, Nobuo Okazaki |
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| Rok vydání: | 2013 |
| Předmět: |
Magnetic Resonance Spectroscopy
Glycoside Hydrolases Stereochemistry Dimer Molecular Sequence Data Chitin Ralstonia Crystallography X-Ray Biochemistry Substrate Specificity chemistry.chemical_compound Bacterial Proteins Catalytic Domain Hydrolase Animals Glycoside hydrolase Amino Acid Sequence Molecular Biology Peptide sequence Plant Proteins Sequence Homology Amino Acid biology Hydrolysis Chitinases Cell Biology biology.organism_classification Gadus morhua chemistry Protein Structure and Folding Mutation Chitinase Mutagenesis Site-Directed biology.protein Peptidoglycan |
| Zdroj: | Journal of Biological Chemistry. 288:18696-18706 |
| ISSN: | 0021-9258 |
| DOI: | 10.1074/jbc.m113.462135 |
| Popis: | Chitinase C from Ralstonia sp. A-471 (Ra-ChiC) has a catalytic domain sequence similar to goose-type (G-type) lysozymes and, unlike other chitinases, belongs to glycohydrolase (GH) family 23. Using NMR spectroscopy, however, Ra-ChiC was found to interact only with the chitin dimer but not with the peptidoglycan fragment. Here we report the crystal structures of wild-type, E141Q, and E162Q of the catalytic domain of Ra-ChiC with or without chitin oligosaccharides. Ra-ChiC has a substrate-binding site including a tunnel-shaped cavity, which determines the substrate specificity. Mutation analyses based on this structural information indicated that a highly conserved Glu-141 acts as a catalytic acid, and that Asp-226 located at the roof of the tunnel activates a water molecule as a catalytic base. The unique arrangement of the catalytic residues makes a clear contrast to the other GH23 members and also to inverting GH19 chitinases. |
| Databáze: | OpenAIRE |
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