Characterization and roles of lysozyme in molluscs

Lysozyme can hydrolyse the β-1.4-glycosidic linkage between the N-acetylmuramic (NAM) and N-acetylglucosamine (NAG). The three major categories of lysozymes in molluscs are Goose-type, Chicken-type and Invertebrate-type lysozymes. The function of lysozymes is served as an innate immune protection against exogenous microbial invasion. The tyoical c-, g- and i-type mollusc lysozymes are secreting type, have signal peptide and eight, six and fourteen cysteine residues, respectively. The c- and g-type lysozymes are highly expressed in hepatopancreas, hemocytes and gills, and weakly expressed in foot and goand tissues of muscle. The i-type lysozyme gene is high expression in different tissues. The three type lysozymes exhibit antibacterial and digestive activity, and i-type lyaozyme also has antifungi activity. Furthermore, this review includes current knowledge regarding to the genomic structure, tissue distribution of mollusc lysozyme, the antimicrobial function and mechanism. The evolution of three type lysozymes in molluscs is also discussed. These lysozymes research may help to understand the basic knowledge and to use it in the production of molluscs.