Molecular cloning and characterization of cDNA of penaeidin-like antimicrobial peptide from tiger shrimp (Penaeus monodon).

We report the molecular cloning and characterization of a penaeidin-like antimicrobial peptide (AMP) complementary DNA from the hemocytes of tiger shrimp (Penaeus monodoni). A tiger shrimp AMP cDNA containing the entire coding region of the peptide, determined by rapid amplification of cDNA 5' and 3' ends and polymerase chain reaction of the messenger RNA isolated from hemocytes of the shrimp, is 683 bp in length with an open reading frame of 222 bp. The deduced amino acid sequence of this antimicrobial peptide consists of 55 amino acid residues of the mature peptide and a signal peptide of 19 amino acid residues. The mature peptide contains a proline-rich domain at the N terminus and 6 cysteine residues at the C terminus, and it shares less than 50% amino acid sequence identity with the mature penaeidins of Litopenaeus vannamei. To demonstrate the bactericidal activity of this peptide, a synthetic peptide was prepared according to the amino acid sequence deduced from the cDNA of tiger shrimp penaeidin-like AMP. By the minimal inhibitory concentration MIC assay, the synthetic peptide was shown to exert bactericidal activity against Escherichia coli, Vibrio harveyi, Vibrio alginolyticu, and Aerococcus viridans. It also inhibited the growth of 2 filamentous fungi, Fusarium pisi and Fusarium oxysporum. Tiger shrimp penaeidin-like AMP mRNA was detected in hemocytes, gills, intestines, eyestalks, hepatopancreas, and muscles of the tiger shrimp by reverse transcriptase-polymerase chain reaction assay. Although the highest level was detected in hemocytes, challenging tiger shrimp with V. harveyi did not result in a significant increase of the mRNA level in hemocytes.