Insect immunity. Isolation from a coleopteran insect of a novel inducible antibacterial peptide and of new members of the insect defensin family.
Injection of heat-killed bacteria into larvae of the large tenebrionid beetle Zophobas atratus (Insecta, Endopterygota, Coleoptera) results in the appearance in the hemolymph of a potent antibacterial activity as evidenced by a plate growth inhibition assay. We have isolated three peptides (A-C) from this immune hemolymph which probably account for most of this activity. Their primary structures were established by a combination of peptide sequencing and molecular mass determination by mass spectrometry. Peptide A, which is bactericidal against Gram-negative cells, is a 74-residue glycine-rich molecule with no sequence homology to known peptides. We propose the name coleoptericin for this novel inducible antibacterial peptide. Peptides B and C are isoforms of a 43-residue peptide which contains 6 cysteines and shows significant sequence homology to insect defensins, initially reported from dipteran insects. This peptide is active against Gram-positive bacteria. The results are discussed in connection with recent studies on inducible antibacterial peptides present in the three other major orders of the endopterygote clade of insects: the Lepidoptera, Diptera, and Hymenoptera.
Bulet
P
P
Laboratoire de Biologie Générale, Université Louis Pasteur, Strasbourg, France.
Cociancich
S
S
Dimarcq
J L
JL
Lambert
J
J
Reichhart
J M
JM
Hoffmann
D
D
Hetru
C
C
Hoffmann
J A
JA
D000595:Amino Acid Sequence; D000818:Animals; D000917:Antibody Formation; D001770:Blood Bactericidal Activity; D001798:Blood Proteins / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D002851:Chromatography, High Pressure Liquid; D001517:Coleoptera / Q000276:immunology*; D023082:Defensins; D006458:Hemolymph / Q000737:chemistry; D007301:Insect Hormones / Q000302:isolation & purification*; D019476:Insect Proteins; D008969:Molecular Sequence Data
D001798:Blood Proteins; D023082:Defensins; D007301:Insect Hormones; D019476:Insect Proteins; C072097:coleoptericin protein, insect