Isolation of cDNA encoding a putative chitinase precursor in the kuruma prawn Penaeus japonicus

Amino acid sequences of chitinases have been determined in insects, plants, yeast, and bacteria, but not in crustaceans. We searched for chitinase-encoding cDNA in the kuruma prawn Penaeus japonicus by polymerase chain reaction (PCR) amplification of hepatopancreas cDNA using degenerate oligonucleotide primers derived from the two conserved regions of known chitinases. Using a PCR product as a probe, a cDNA clone was isolated. This clone contains an open reading frame for a protein (named Pjchi-1) of 572 amino acids that exhibits sequence similarities to known chitinases, especially to a chitinase from the tobacco hornworm Manduca sexta. Transcription of the mRNA was detected in the hepatopancreas but not in epidermal tissues.