Gallinacins: cysteine‐rich antimicrobial peptides of chicken leukocytes

Abstract

We purified three homologous antimicrobial peptides ('gallinacins') from chicken leukocytes, examined their antimicrobial activity in vitro, and established their primary sequences by a combination of gas phase microsequencing and on-line IX-ESI-MS analysis of endo-and exoprotease peptide digests. The peptides contained 3&39 amino acid residues, were relatively cationic due to their numerous lysine and arginine residues, and each contained 3 intramolecular cystine disulfide bonds. Gallinacins showed primary sequence homology to the recently delineated p-defensin family, heretofore found only in the respiratory epithelial cells and neutrophils of cattle, suggesting that /3-defensins originated at least 250 million years ago, before avian and mammalian lineages diverged. The 9 invariant residues (6 cysteines, 2 glycines and 1 proline) common to avian gallinacins and bovine p-defensins are likely to constitute the essential primary structural motif of this ancient family of host-defense peptides.

Bioinformatic discovery and initial characterisation of nine novel antimicrobial peptide genes in the chicken

“…In mammals, α-defensins and β-defensins are two structurally distinct cationic, cysteine-rich AMPs, which differ in size and in the spacing of a six-cysteine structural motif (Liu et al 1997). α-defensins are unique to mammals, but β-defensins are much more widely distributed and, in the chicken, four β-defensins, known as gallinacins, have been described to date (Evans et al 1994;Harwig et al 1994;Zhao et al 2001). Homologous peptides have also been described in the turkey (Evans et al 1994;Zhao et al 2001).…”

Cathelicidins: a novel protein family with a common proregion and a variable C‐terminal antimicrobial domain

“…The importance of these peptides can be inferred from their specific localization at sites which are exposed to microbial invasion as well as in the professional phagocytes. They are in fact produced in the epithelia of amphibia [3], mammals [4][5][6] and insects [2,7], are secreted into internal body fluids in arthropodes [2,7] and are stored in the cytoplasmic granules of professional phagocytes of mammals and birds [8][9][10][11].…”

“…The spectrum of organisms susceptible to these peptides is broad [2][3][4][5][6][7][8][9][10][11], including various bacteria, protozoa, fungi, and in some cases, virally infected and tumor cells. Their antimicrobial and cytotoxic effects are mediated by the ability to bind and permeabilize the surface membrane of the target cells [2,4,7,10,14].…”

Variability and evolution of bovine β-defensin genes

“…3 Based on their size and the spatial position of the six cysteine residues, animal defensins are classified as a-, b-, y-defensins of vertebrates (mammalia and birds) and insect defensins. To date, vertebrate defensins were identified in numerous species: mice, [6][7][8] birds-where they are called gallinacins- 9 rats, 10 cattle, 11,12 goats, 13 sheeps, 14 humans, 8,15,16 and non-human primates [17][18][19][20] (reviewed in Martin et al, 4 Hughes, 21 Schroder, 22 and Lehrer and Ganz 23 ). Interestingly, domestic cattle (Bos taurus) was shown to share a broad spectrum of different b-defensins, for example, tap (tracheal antimicrobial peptide), lap (lingual antimicrobial peptide), bnbd (bovine neutrophil peptide), nbd12 (neutrophil beta defensin 12), and ebd (enteric beta defensin).…”