Cloning and sequence analysis of the gene encoding a thermostable chitinase from Streptomyces thermoviolaceus OPC-520.

The gene (chi40) encoding a thermostable chitinase from Streptomyces thermoviolaceus OPC-520 was cloned in Escherichia coli JM109 using pUC18. The nucleotide (nt) sequence of chi40 has been determined. A single open reading frame (ORF) encoded a protein consisting of 414 amino acids (aa) with a M(r) of 43,838. The deduced aa sequence of the cloned chitinase (Chi40) showed striking homology (74%) with Chi63 from Streptomyces plicatus. Comparison with other chitinases revealed that Chi40 contained the two conserved regions common to microbial and plant chitinases. Furthermore, the putative promoter region of chi40, which might be involved in the repression and induction of such catabolite-controlled genes, was detected by the DNA sequence alignments.