A novel insect defensin mediates the inducible antibacterial activity in larvae of the dragonfly Aeschna cyanea (Paleoptera, Odonata).
The injection of low doses of bacteria into the aquatic larvae of dragonflies (Aeschna cyanea, Odonata, Paleoptera) induces the appearance in their hemolymph of a potent antibacterial activity. We have isolated a 38-residue peptide from this hemolymph which is strongly active against Gram-positive bacteria and also shows activity against one of the Gram-negative bacteria which was tested. The peptide is a novel member of the insect defensin family of inducible antibacterial peptides, which had so far only been reported from the higher insect orders believed to have evolved 100 million years after the Paleoptera. Aeschna defensin is more potent than defensin from the dipteran Phormia, from which its structure differs in several interesting aspects, which are discussed in the paper.
Bulet
P
P
Laboratoire de Biologie Générale, Université Louis Pasteur, Unité de Recherche Associée, Centre National de la Recherche Scientifique 1490, Strasbourg, France.
Cociancich
S
S
Reuland
M
M
Sauber
F
F
Bischoff
R
R
Hegy
G
G
Van Dorsselaer
A
A
Hetru
C
C
Hoffmann
J A
JA
D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000302:isolation & purification*; D023181:Antimicrobial Cationic Peptides; D001770:Blood Bactericidal Activity; D001798:Blood Proteins / Q000302:isolation & purification* / Q000502:physiology; D023082:Defensins; D006458:Hemolymph / Q000737:chemistry; D019476:Insect Proteins; D007313:Insecta / Q000276:immunology*; D007814:Larva / Q000276:immunology; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D010455:Peptides / Q000302:isolation & purification / Q000502:physiology*
D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D001798:Blood Proteins; D023082:Defensins; D019476:Insect Proteins; D010455:Peptides; C077840:defensin protein, Aeshna cyanea