Characterization and functional analysis of a chitinase gene: Evidence of Ch-chit participates in the regulation of biomineralization in Crassostrea hongkongensis

Abstract Chitinase is a key enzyme in many organisms that functions as a defense against chitin-coated pathogens or as a digestive enzyme to hydrolyze dietary chitin. Chitin is also essential for the formation of organic frameworks, involves in various biological processes, including shell formation. However, the function of chitinase of Crassostrea hongkongensis has not yet been determined. In this study, we obtained a full Ch-chit sequence from C. hongkongensis. The full length of Ch-chit cDNA encoded a predicted 470-amino acid protein, contained a signal peptide, a Glyco 18 domain, a low complexity domain, and a transmembrane domain. Phylogenetic analysis showed that Ch-chit clustered with Chit3-lp of other bivalves. In different stages of larvae development, the expression of Ch-chit in the trochophore larvae was the highest and was significantly higher than that in other stages (P