The complete amino acid sequence of yam (Dioscorea japonica) chitinase. A newly identified acidic class I chitinase.
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.
Araki
T
T
Department of Biochemistry, School of Agriculture, Kyushu Tokai University, Japan.
Funatsu
J
J
Kuramoto
M
M
Konno
H
H
Torikata
T
T
D000595:Amino Acid Sequence; D002688:Chitinases / Q000235:genetics*; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D014675:Vegetables / Q000201:enzymology*
D002688:Chitinases