PENAEIDINS, A NEW FAMILY OF ANTIMICROBIAL PEPTIDES ISOLATED FROM THE SHRIMP PENAEUS-VANNAMEI (DECAPODA)

We report here the isolation of three members of a new family of antim icrobial peptides from the hemolymph of shrimps Penaeus vannamei in wh ich immune response has not been experimentally induced. The three mol ecules display antimicrobial activity against fungi and bacteria with a predominant activity against Gram-positive bacteria. The complete se quences of these peptides were determined by a combination of enzymati c cleavages, Edman degradation, mass spectrometry, and cDNA cloning us ing a hemocyte cDNA library. The mature molecules (50 and 62 residues) are characterized by an NH2-terminal domain rich in proline residues and a COOH-terminal domain containing three intramolecular disulfide b ridges. One of these molecules is post-translationally modified by a p yroglutamic acid at the first position. Comparison of the data obtaine d from the cDNA clones and mass spectrometry showed that two of these peptides are probably COOH-terminally amidated by elimination of a gly cine residue. These molecules with no evident homology to other hither to described antimicrobial peptides were named penaeidins.