Molecular cloning, characterization and expression analysis of a chymotrypsin-like serine protease from kuruma shrimp Marsupenaeus japonicus

The mRNA encoding chymotrypsin-like serine protease (Mj-chy) from a kuruma shrimp Marsupenaeus japonicus hepatopancreas was identified as a peptidoglycan-inducible gene by 5'-end serial analysis of gene expression. The transcript of Mj-chy consists of a 816-nucleotide open reading frame encoding 271 amino acids, including a signal peptide of 17 amino acids and a trypsin-like serine protease domain of 219 amino acids. Like most serine proteases, Mj-chy has a catalytic triad consisting of histidine, aspartic acid and serine, and six cysteine residues forming three disulfide bridges. In a phylogenetic analysis, the trypsin-like serine protease domain clustered with invertebrate chymotrypsins and was closely related to chymotrypsin-like serine protease from Chinese shrimp Fenneropenaeus chinensis and chymotrypsin BI from Pacific white shrimp Litopenaeus vannamei. Mj-chy was detected in the hepatopancreas, stomach and intestine, and exhibited increased expression in defense-related tissues (i.e., hemocytes, lymphoid organ and hepatopancreas) after peptidoglycan stimulation.