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Nishitani Y, Horiuchi A, Aslam M, Kanai T, Atomi H, Miki K. Crystal structures of an archaeal chitinase ChiD and its ligand complexes. Glycobiology 2018; 28:418-426. [PMID: 29800365 DOI: 10.1093/glycob/cwy024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 03/20/2018] [Indexed: 11/13/2022] Open
Abstract
Chitinase D (designated as Pc-ChiD) was found in a hyperthermophilic archaeon, Pyrococcus chitonophagus (previously described as Thermococcus chitonophagus), that was isolated from media containing only chitin as carbon source. Pc-ChiD displays chitinase activity and is thermostable at temperatures up to 95°C, suggesting its potential for industrial use. Pc-ChiD has a secretion signal peptide and two chitin-binding domains (ChBDs) in the N-terminal domain. However, the C-terminal domain shares no sequence similarity with previously identified saccharide-degrading enzymes and does not contain the DXDXE motif conserved in the glycoside hydrolase (GH) 18 family chitinases. To elucidate its overall structure and reaction mechanism, we determined the first crystal structures of Pc-ChiD, both in the ligand-free form and in complexes with substrates. Structure analyses revealed that the C-terminal domain of Pc-ChiD, Pc-ChiD(ΔBD), consists of a third putative substrate-binding domain, which cannot be predicted from the amino acid sequence, and a catalytic domain structurally similar to that found in not the GH18 family but the GH23 family. Based on the similarity with GH23 family chitinase, the catalytic residues of Pc-ChiD were predicted and confirmed by mutagenesis analyses. Moreover, the specific C-terminal 100 residues of Pc-ChiD are important to fix the putative substrate-binding domain next to the catalytic domain, contributing to the structure stability as well as the long chitin chain binding. Our findings reveal the structure of a unique archaeal chitinase that is distinct from previously known members of the GH23 family.
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Affiliation(s)
- Yuichi Nishitani
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Ayumi Horiuchi
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Mehwish Aslam
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Tamotsu Kanai
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan.,JST, CREST, Gobancho 7, Chiyoda-ku, Tokyo 102-0076, Japan
| | - Haruyuki Atomi
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan.,JST, CREST, Gobancho 7, Chiyoda-ku, Tokyo 102-0076, Japan
| | - Kunio Miki
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.,JST, CREST, Gobancho 7, Chiyoda-ku, Tokyo 102-0076, Japan
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Arimori T, Kawamoto N, Shinya S, Okazaki N, Nakazawa M, Miyatake K, Fukamizo T, Ueda M, Tamada T. 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. J Biol Chem 2013; 288:18696-706. [PMID: 23658014 DOI: 10.1074/jbc.m113.462135] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
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.
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Affiliation(s)
- Takao Arimori
- Quantum Beam Science Directorate, Japan Atomic Energy Agency, 2-4 Shirakata-Shirane, Tokai, Ibaraki 319-1195, Japan
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Einspahr H, Weiss MS. Crystals on the cover 2012. Acta Crystallogr Sect F Struct Biol Cryst Commun 2012; 68:1. [PMID: 22232160 PMCID: PMC3253823 DOI: 10.1107/s1744309111053759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2011] [Accepted: 12/23/2011] [Indexed: 11/10/2022]
Abstract
Editorial.
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Affiliation(s)
| | - Manfred S. Weiss
- Helmholtz-Zentrum Berlin für Materialien und Energie, Macromolecular Crystallography (BESSY-MX), Albert-Einstein-Strasse 15, D-12489 Berlin, Germany
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