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204 a.a.
_ZN
Key reference
DOI no: 10.1111/j.1742-4658.2006.05487.x FEBS J 273:4889-4900 (2006) PubMed id: 17010167
Crystal structure and enzymatic properties of a bacterial family 19 chitinase reveal differences from plant enzymes. I.A.Hoell, B.Dalhus, E.B.Heggset, S.I.Aspmo, V.G.Eijsink. ABSTRACT
We describe the cloning, overexpression, purification, characterization and crystal structure of chitinase G, a single-domain family 19 chitinase from the Gram-positive bacterium Streptomyces coelicolor A3(2). Although chitinase G was not capable of releasing 4-methylumbelliferyl from artificial chitooligosaccharide substrates, it was capable of degrading longer chitooligosaccharides at rates similar to those observed for other chitinases. The enzyme was also capable of degrading a colored colloidal chitin substrate (carboxymethyl-chitin-remazol-brilliant violet) and a small, presumably amorphous, subfraction of alpha-chitin and beta-chitin, but was not capable of degrading crystalline chitin completely. The crystal structures of chitinase G and a related Streptomyces chitinase, chitinase C [Kezuka Y, Ohishi M, Itoh Y, Watanabe J, Mitsutomi M, Watanabe T & Nonaka T (2006) J Mol Biol358, 472-484], showed that these bacterial family 19 chitinases lack several loops that extend the substrate-binding grooves in family 19 chitinases from plants. In accordance with these structural features, detailed analysis of the degradation of chitooligosaccharides by chitinase G showed that the enzyme has only four subsites (- 2 to + 2), as opposed to six (- 3 to + 3) for plant enzymes. The most prominent structural difference leading to reduced size of the substrate-binding groove is the deletion of a 13-residue loop between the two putatively catalytic glutamates. The importance of these two residues for catalysis was confirmed by a site-directed mutagenesis study.
Literature references that cite this PDB file's key reference
PubMed id Reference
19143844 M.E.Lacombe-Harvey, T.Fukamizo, J.Gagnon, M.G.Ghinet, N.Dennhart, T.Letzel, and R.Brzezinski (2009).
Accessory active site residues of Streptomyces sp. N174 chitosanase: variations on a common theme in the lysozyme superfamily.FEBS J, 276, 857-869.
19629717 W.Ubhayasekera, R.Rawat, S.W.Ho, M.Wiweger, S.Von Arnold, M.L.Chye, and S.L.Mowbray (2009).
The first crystal structures of a family 19 class IV chitinase: the enzyme from Norway spruce.Plant Mol Biol, 71, 277-289.
18214468 Y.Honda, H.Taniguchi, and M.Kitaoka (2008).
A reducing-end-acting chitinase from Vibrio proteolyticus belonging to glycoside hydrolase family 19.Appl Microbiol Biotechnol, 78, 627-634.
17608716 W.Ubhayasekera, C.M.Tang, S.W.Ho, G.Berglund, T.Bergfors, M.L.Chye, and S.L.Mowbray (2007).
Crystal structures of a family 19 chitinase from Brassica juncea show flexibility of binding cleft loops.FEBS J, 274, 3695-3703.
PDB codes: 2z37 2z38 2z39 The most recent references are shown first. Citation data come partly from CiteXplore and partly from an automated harvesting procedure. Note that this is likely to be only a partial list as not all journals are covered by either method. However, we are continually building up the citation data so more and more references will be included with time. Where a reference describes a PDB structure, the PDB codes are shown on the right.
