Cloning and sequencing of the gene encoding chitinase ChiA from Xanthomonas sp. strain AK and some properties of ChiA

The chiA gene encoding chitinase A was cloned into Escherichia coli from Xa nthomonas sp. strain AK and its nucleotide sequence was determined. The str uctural gene consists of 1788 bp encoding 596 amino acids with a predicted molecular weight of 62,122. The deduced ChiA is a modular enzyme composed o f an N-terminal signal peptide and four domains in the following order: a c hitin-binding domain, two fibronectin type III domains, and a family 18 cat alytic domain. ChiA purified from the recombinant E. coli had temperature a nd pH optima at 35 degrees C and 4.5, respectively. The K-m and V-max value s for colloidal chitin were estimated to be 1.8 mg/ml and 8.7 mu mol/min/mg , respectively.