CDNA CLONING OF 3 CECROPIN-LIKE ANTIMICROBIAL PEPTIDES (STYELINS) FROM THE TUNICATE, STYELA-CLAVA

We cloned precursors of three new antimicrobial peptides, Styelins C, D and E, from a pharyngeal cDNA library of a tunicate, Styela clava. P reprostyelins resembled dipteran preprocecropins, while the mature dom ain of Styelin C resembled Cecropin P1, an antimicrobial peptide purif ied from the porcine intestine. Beginning with the last 6 residues of their signal sequences, Styelin C and Cecropin 1 from Drosophila viril is had 8/11 identical amino acids (72.7%). Moreover, 4 of the last 6 r esidues of their mature peptide domains were also identical. Styelins were shorter, by 8 residues, than dipteran cecropins and preprostyelin s contained a conserved, polyanionic C-terminal extension that was abs ent in preprocecropins. Delineation of cecropin-like antimicrobial pep tides in a protochordate supports the antiquity of this family as effe cters of innate immunity in animals and it increases the likelihood th at additional cecropin-like peptides will be found among other evoluti onary descendants of protochordates - vertebrates. (C) 1997 Federation of European Biochemical Societies.