cDNA cloning and antibacterial activities of cecropin D like peptides fromAgrius convolvuli

We have characterized full-length cDNAs encoding two isoforms of agriusin, cecropin D-like antibacterial peptide, present in the hemolymph of the immu nized Agrius convolvuli larvae. The cloned cDNAs of agriusins 1 and 2 conta in 331 and 329 bp, respectively. The nucleotide sequencing of cDNAs showed that they encode 62 amino acids, whose mature portion was deduced to consis t of 38 amino acid residues with over 94% sequence identity. In the sequenc e homology search, mature agriusin 1 showed over 86 and 71% amino acid sequ ence homology with bactericidin 4 from Manduca sexta and cecropin D from Hy alophora cecropia, respectively. Since it was demonstrated from the deduced amino acid sequences that the C-terminal residues of agriusins are followe d by a Gly residue, two types of synthetic agriusin 1 (syn-agriusin 1 amide and acid) were prepared to verify if natural agriusin 1 is C-terminally am idated. From acid-urea PAGE and reversed phase HPLC profiles to compare two synthetic peptides, we could confirm that the C-terminal amino acid residu e of natural agriusin 1, like several cecropins so far identified, is amida ted. Finally, our antibacterial assay performed with two syn-agriusins 1 re vealed that there is little difference between antibacterial activities of both peptides against Gram-positive and Gram-negative bacteria. Arch. Insec t Biochem, Physiol. 45:149-155, 2000. (C) 2001 Wiley-Liss, Inc.