title: Ovodefensins, an Oviduct-Specific Antimicrobial Gene Family, Have Evolved in Birds and Reptiles to Protect the Egg by Both Sequence and Intra-Six-Cysteine Sequence Motif Spacing.
abstract: Ovodefensins are a novel beta defensin-related family of antimicrobial peptides containing conserved glycine and six cysteine residues. Originally thought to be restricted to the albumen-producing region of the avian oviduct, expression was found in chicken, turkey, duck, and zebra finch in large quantities in many parts of the oviduct, but this varied between species and between gene forms in the same species. Using new search strategies, the ovodefensin family now has 35 members, including reptiles, but no representatives outside birds and reptiles have been found. Analysis of their evolution shows that ovodefensins divide into six groups based on the intra-cysteine amino acid spacing, representing a unique mechanism alongside traditional evolution of sequence. The groups have been used to base a nomenclature for the family. Antimicrobial activity for three ovodefensins from chicken and duck was confirmed against Escherichia coli and a pathogenic E. coli strain as well as a Gram-positive organism, Staphylococcus aureus, for the first time. However, activity varied greatly between peptides, with Gallus gallus OvoDA1 being the most potent, suggesting a link with the different structures. Expression of Gallus gallus OvoDA1 (gallin) in the oviduct was increased by estrogen and progesterone and in the reproductive state. Overall, the results support the hypothesis that ovodefensins evolved to protect the egg, but they are not necessarily restricted to the egg white. Therefore, divergent motif structure and sequence present an interesting area of research for antimicrobial peptide design and understanding protection of the cleidoic egg.
authors.affiliation: Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, Scotland, United Kingdom natasha.whenham@roslin.ed.ac.uk.
authors.forename: Natasha
authors.initials: N
authors.lastname: Whenham
authors.affiliation: Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, Scotland, United Kingdom.
authors.forename: Tian Chee
authors.initials: TC
authors.lastname: Lu
authors.affiliation: Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, Scotland, United Kingdom.
authors.forename: Maisarah B M
authors.initials: MB
authors.lastname: Maidin
authors.affiliation: Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, Scotland, United Kingdom.
authors.forename: Peter W
authors.initials: PW
authors.lastname: Wilson
authors.affiliation: College of Medical, Veterinary and Life Sciences (MVLS), University of Glasgow, Glasgow, Scotland, United Kingdom.
authors.forename: Maureen M
authors.initials: MM
authors.lastname: Bain
authors.affiliation: College of Medical, Veterinary and Life Sciences (MVLS), University of Glasgow, Glasgow, Scotland, United Kingdom.
authors.forename: M Lynn
authors.initials: ML
authors.lastname: Stevenson
authors.affiliation: Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, Scotland, United Kingdom.
authors.forename: Mark P
authors.initials: MP
authors.lastname: Stevens
authors.affiliation: AB Vista Feed Ingredients, Marlborough, Wiltshire, England, United Kingdom.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Bedford
authors.affiliation: Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, Scotland, United Kingdom.
authors.forename: Ian C
authors.initials: IC
authors.lastname: Dunn
mesh_terms: D000818:Animals; D005075:Biological Evolution; D002645:Chickens; D019295:Computational Biology; D023082:Defensins / Q000378:metabolism*; D010063:Ovum / Q000378:metabolism*; D010802:Phylogeny
chemical_list: D023082:Defensins
keywords: Escherichia coli; Staphylococcus aureus; antimicrobial; chicken; defensin; egg; evolution; oviduct; steroid