title: The complete amino acid sequence of yam (Dioscorea japonica) chitinase. A newly identified acidic class I chitinase.
abstract: The complete amino acid sequence of acidic chitinase from yam (Dioscorea japonica) aerial tubers was determined. The protein is composed of a single polypeptide chain of 250 amino acid residues and has a calculated molecular mass of 27,890 Da. There is an NH2-terminal domain, a hinge region, and a main structure, typical for class I chitinases (Shinshi, H., Neuhaus, J.-M., Ryals, J., and Meins, F., Jr. (1990) Plant Mol. Biol. 14, 357-368). We have obtained the first evidence for an acidic class I chitinase. Comparison with sequences of other class I chitinases revealed approximately 40% sequence similarity, a value lower than that for other class I chitinases (70-80%). We assume that there is a local conformational change in the molecule; cysteine residues that probably form disulfide bonds are completely conserved, with the exception of Cys-178. The difference in structure between this chitinase and other basic class I chitinases suggests that acidic and basic isoforms should be grouped into subclasses; this protein is an ethylene- or a pathogen-independent chitinase produced by a gene that is inherent in the tuber.
authors.affiliation: Department of Biochemistry, School of Agriculture, Kyushu Tokai University, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Araki
authors.forename: J
authors.initials: J
authors.lastname: Funatsu
authors.forename: M
authors.initials: M
authors.lastname: Kuramoto
authors.forename: H
authors.initials: H
authors.lastname: Konno
authors.forename: T
authors.initials: T
authors.lastname: Torikata
mesh_terms: D000595:Amino Acid Sequence; D002688:Chitinases / Q000235:genetics*; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D014675:Vegetables / Q000201:enzymology*
chemical_list: D002688:Chitinases