cDNA Cloning and Antibacterial Activiteis of Cecropin D-Like Peptides from Agrius convovuli

摘要

We have characterized full-length cDNAs encoding two isoforms of agriusin, cecropin D-like antibacterial peptide, present in the hemolymph of the immunized Agrius convolvuli larvae. The cloned cDNAs of agriusins 1 and 2 contain 331 and 329 bp, re- spectively. The nucleotide sequencing of cDNAs showed that they encode 62 amino acids, whose mature portion was deduced to consist of 38 amino acid residues with over 94% sequence identity. In the sequence homology search, mature agriusin 1 showed over 86 and 71% amino acid sequence homology with bactericidin 4 from Manduca sexta and cecropin D from Hyalophora cecropia, respectively. Since it was demonstrated from the deduced amino acid sequences that the C-terminal residues of agriusins are followed 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 amidated. From acid-urea PAGE and reversed phase HPLC profiles to com- pare two synthetic peptides, we could confirm that the C-termi- nal amino acid residue of natural agriusin 1, like several cecropins so far identified, is amidated. Finally, our antibacte- rial assay performed with two syn-agriusins 1 revealed that there is little difference between antibacterial activities of both pep- tides against Gram-positive and Gram-negative bacteria. Arch. Insect Biochem. Phvsiol. 45:149-155. 2000.