Molecular cloning of a genomic DNA encoding yam class IV chitinase.
Genomic DNA for a class IV chitinase was cloned from yam (Dioscorea opposita Thunb) leaves and sequenced. The deduced amino acid sequence shows 50 to 59% identity to class IV chitinases from other plants. The yam chitinase, however, has an additional sequence of 8 amino acids (a C-terminal extension) following the cysteine that was reported as the last amino acid for other class IV chitinases; this extension is perhaps involved in subcellular localization. A homology model based on the structure of a class II chitinase from barley was used as an aid to interpreting the available data. The analysis suggests that the class IV enzyme recognizes an even shorter segment of the substrate than class I or II enzymes. This observation might help to explain why class IV enzymes are better suited to attack against pathogen cell walls.
Laboratory of Biochemistry, Department of Biological Science, Faculty of Agriculture, Yamaguchi University, Yamaguchi 753-8515, Japan.
Takuji
T
Mitsunaga
Minoru
M
Iwase
Wimal
W
Ubhayasekera
Sherry L
SL
Mowbray
Daizo
D
Koga
D000595:Amino Acid Sequence; D001483:Base Sequence; D002384:Catalysis; D002688:Chitinases / Q000737:chemistry / Q000145:classification / Q000235:genetics*; D003001:Cloning, Molecular; D027742:Dioscorea / Q000201:enzymology* / Q000235:genetics; D017343:Genes, Plant; D008958:Models, Molecular; D008969:Molecular Sequence Data; D018515:Plant Leaves / Q000201:enzymology / Q000235:genetics; D017434:Protein Structure, Tertiary; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment
D002688:Chitinases