Chitinase, which catalyzes the hydrolysis of the β-1,4-acetyl-D-glucosamine linkages of the fungal cell wall polymer chitin, is involved in inducible plants defense system. By construction of cabbage (Brassica oleracea var.capitata) genomic library and screening the library with pRCH8, a probe of rice chitinase gene fragment, a chitinase genomic sequence was isolated. The complete nucleotide sequence of the putative cabbage chitinase gene (cabch29) was determined, with its longest open reading frame (ORF)encoding a polypeptide of 413 aa. This polypeptide consists of a 21 aa N-terminal signal peptide,two chitin-binding domains different from those of other classes of plant chitinases, and a catalytic domain. Homology analysis illustrated that this cabch29 gene has 58.8% identity at the nucleotide level with the pRCH8 ORF probe and has 50% identity at the amino acid level with the catalytic domains of chitinase from bean,maize and sugar beet. Meanwhile,several kinds of cis- elements,such as TAT.A box, CAAT box, GATA motif, ASF-1 binding site, wound-response elements and AATAAA, have also been discovered in the flanking region of cabch29 gene.
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