Insect immunity: isolation from immune blood of the dipteran Phormia terranovae of two insect antibacterial peptides with sequence homology to rabbit lung macrophage bactericidal peptides.

Abstract

We have isolated from the hemolymph of immunized larvae of the dipteran insect Phormia terranovae two peptides that are selectively active against Gram-positive bacteria. They are positively charged peptides of 40 residues containing three intramolecular disulfide bridges and differ from one another by only a single amino acid. These peptides are neither functionally nor structurally related to any known insect immune response peptides but show significant homology to microbicidal cationic peptides from mammalian granulocytes (defensins). We propose the name "insect defensins" for these insect antibiotic peptides.

A novel insect defensin mediates the inducible antibacterial activity in larvae of the dragonfly Aeschna cyanea (Paleoptera, Odonata)

“…The peptide sequence of the newly isolated molecule from Aeschna shows significant similarity to insect defensins. These peptidcs were originally isolated from cell cultures of Sarcophaguperegrina [6] and challenged larvae of the dipteran Phwniiu terrunovue [5]. The name insect defensins was proposed for the Phormiu peptide on the basis of sequence similarities with the defensins, which are antibacterial peptides present in mammalian neutrophil polymorphonuclear leucocytes (sec [19] for revicw).…”

“…The peptide is a 38-residue moleculc with 30% overall sequence similarity to the insect defensins recently characterized in immune blood of Phormia terranovae (Diptera) [5]. The dragonfly peptide has six cysteines in common with its dipteran homologue and the cysteine array is similar in both species.…”

“…Four groups of inducible antibacterial peptides or polypeptides have been isolated and totally or partially characterized, which are: the cecropins, 4-kDa cationic pcptides devoid of cysteines, which form two amphipathic tl helices ( [3], reviewed in [4]); the insect defensins, 4-kDa cationic peptides which contain six cysteine residues engaged in three intramolecular disulfide bridges and characterized by an amphipathic CI helix linked via two disulfide bridges to an antiparallel j? sheet [5][6][7][8]; three as yet incompletely characterized, small (2 -4-kDa) cationic proline-rich peptides or peptide families which are the apidaecins 191, abaecin [lo] and the drosocins (Bulet P. and Dimarcq J. L., unpublished results); several distinct polypeptides ranging in size over 8 -27 kDa, mostly cationic and frcquently rich in Correspondence to J. A. Hoffmann, Laboratoirc de Biologie Generalc, UniversitC Louis Pasteur, URA CNRS 1490, Bases xnoleculaires de la rtponsc immunitaire des insectes, 12 rue de l'universite, F-67000 Strasbourg, France…”

Gallinacins: cysteine‐rich antimicrobial peptides of chicken leukocytes

“…Although peptides analogous to mammalian defensins and protegrins have also been found in invertebrates, including insects (e.g. 'insect defensins' [26,27]) and horseshoe crabs (e.g. 'tachyplesins' [28,29]) and similar cysteine-rich antimicrobial peptides are also produced by many plants [30], surprisingly little is known of the evolutionary history and relatedness of these various peptide families.…”

The humoral antibacterial response of Drosophila

“…However, as Boman later put it, 'the biochemistry behind this phenomenon could not be worked out at that time' [7]. In spite of the obvious interest of Drosophila as a model system, Boman and associates turned to the large pupae of the Cecropia moth for the first successful isolation of induced antibacterial molecules (cecropins [8] and attacins [9]), while other groups worked on large-sized fly species, like Sarcophaga peregrina (isolation of the cecropin-like sarcotoxins I [lo], the attacin-related sarcotoxins II [l I] and sapecin, a homologue of insect defensin [I 21) or Phormiu terranovae (isolation of diptericins [13] and insect defensins [14]) (for reviews on these peptides, see e.g. [15-l 71).…”