Abstract
Chitinase A of Streptomyces cyaneus SP-27 or chitinase I of Bacillus circulans KA-304 showed the protoplast-forming activity when combined with α-1,3-glucanase of B. circulans KA-304.
The gene of chitinase A was cloned. It consisted of 903 nucleotides encoding 301 amino acid residues, including a putative signal peptide (35 amino acid residues). The deduced N-terminal moiety of chitinase A showed sequence homology with the chitin-binding domain of chitinase F from Streptomyces coelicolor and chitinase 30 from Streptomyces olivaceoviridisis. The C-terminal moiety also showed high sequence similarity to the catalytic domain of several Streptomyces family 19 chitinases as well as that of chitinase I of B. circulans KA-304.
Recombinant chitinase A was expressed in Escherichia coli Rosetta-gami B (DE 3). The properties of the recombinant enzyme were almost the same as those of chitinase A purified from a culture filtrate of S. cyaneus SP-27. The recombinant enzyme was superior to B. circulans KA-304 chitinase I not only in respect to protoplast forming activity in a mixture containing α-1,3-glucanase, but also to antifungal activity and powder chitin-hydrolyzing activity.
