CHARACTERIZATION OF CHITINASE-C FROM A MARINE BACTERIUM, ALTEROMONAS SP. STRAIN O-7, AND ITS CORRESPONDING GENE AND DOMAIN-STRUCTURE

One of the chitinase genes of Alteromonas so. strain O-7, the chitinas e C-encoding gene !(chiC), was cloned, and the nucleotide sequence was determined,,in open reading frame coded for a protein of 430 amino ac ids with a predicted molecular mass of 46,680 Da. Alignment of the ded uced amino acid sequence demonstrated that ChiC contained three functi onal domains, the N-terminal domain, a fibronectin type III-like domai n, and a catalytic domain, The N-terminal domain (59 amino acids) was similar to that found in the C-terminal extension of ChiA (50 amino ac ids) of this strain and furthermore showed significant sequence homolo gy to the regions found in several chitinases and cellulases. Thus, to evaluate the role of the domain, we constructed the hybrid gene that directs the synthesis of the fusion protein with glutathione S-transfe rase activity. Both the fusion protein and the N-terminal domain itsel f bound to chitin, indicating that the N-terminal domain of ChiC const itutes an independent chitin-binding domain.