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PDBsum entry 3w6c
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References listed in PDB file
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Key reference
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Title
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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.
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Authors
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T.Arimori,
N.Kawamoto,
S.Shinya,
N.Okazaki,
M.Nakazawa,
K.Miyatake,
T.Fukamizo,
M.Ueda,
T.Tamada.
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Ref.
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J Biol Chem, 2013,
288,
18696-18706.
[DOI no: ]
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PubMed id
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Abstract
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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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