Three-dimensional NMR structure of Hen Egg Gallin (Chicken Ovodefensin) reveals a new variation of the β-defensin fold.
Gallin is a 41-residue protein, first identified as a minor component of hen egg white and found to be antimicrobial against Escherichia coli. Gallin may participate in the protection of the embryo during its development in the egg. Its sequence is related to antimicrobial β-defensin peptides. In the present study, gallin was chemically synthesized 1) to further investigate its antimicrobial spectrum and 2) to solve its three-dimensional NMR structure and thus gain insight into structure-function relationships, a prerequisite to understanding its mode(s) of action. Antibacterial assays confirmed that gallin was active against Escherichia coli, but no additional antibacterial activity was observed against the other Gram-positive or Gram-negative bacteria tested. The three-dimensional structure of gallin, which is the first ovodefensin structure to have been solved to date, displays a new five-stranded arrangement. The gallin three-dimensional fold contains the three-stranded antiparallel β-sheet and the disulfide bridge array typical of vertebrate β-defensins. Gallin can therefore be unambiguously classified as a β-defensin. However, an additional short two-stranded β-sheet reveals that gallin and presumably the other ovodefensins form a new structural subfamily of β-defensins. Moreover, gallin and the other ovodefensins calculated by homology modeling exhibit atypical hydrophobic surface properties, compared with the already known vertebrate β-defensins. These specific structural features of gallin might be related to its restricted activity against E. coli and/or to other yet unknown functions. This work provides initial understanding of a critical sequence-structure-function relationship for the ovodefensin family.
From Institut National de la Recherche Agronomique (INRA), UR83 Recherches Avicoles, Fonction et Régulation des Protéines de l'œuf, F-37380 Nouzilly, France; Université François Rabelais, UMR 1100, F-37032 Tours, France; INSERM, Centre d'Etude des Pathologies Respiratoires, UMR 1100/EA6305, F-37032 Tours, France.
Virginie
V
Hervé
Centre de Biophysique Moléculaire, CNRS UPR 4301, Université d'Orléans, Rue Charles Sadron, 45071 Orléans Cedex 2, France.
Hervé
H
Meudal
Plate-forme d'Analyse Intégrative des Biomolécules UMR INRA 85-CNRS 7247, Université François Rabelais, Institut Français du Cheval et de l'Équitation (IFCE), F-37380 Nouzilly, France.
Valérie
V
Labas
From Institut National de la Recherche Agronomique (INRA), UR83 Recherches Avicoles, Fonction et Régulation des Protéines de l'œuf, F-37380 Nouzilly, France.
Sophie
S
Réhault-Godbert
From Institut National de la Recherche Agronomique (INRA), UR83 Recherches Avicoles, Fonction et Régulation des Protéines de l'œuf, F-37380 Nouzilly, France.
Joël
J
Gautron
From Institut National de la Recherche Agronomique (INRA), UR83 Recherches Avicoles, Fonction et Régulation des Protéines de l'œuf, F-37380 Nouzilly, France.
Magali
M
Berges
From Institut National de la Recherche Agronomique (INRA), UR83 Recherches Avicoles, Fonction et Régulation des Protéines de l'œuf, F-37380 Nouzilly, France.
Nicolas
N
Guyot
Centre de Biophysique Moléculaire, CNRS UPR 4301, Université d'Orléans, Rue Charles Sadron, 45071 Orléans Cedex 2, France.
Agnès F
AF
Delmas
From Institut National de la Recherche Agronomique (INRA), UR83 Recherches Avicoles, Fonction et Régulation des Protéines de l'œuf, F-37380 Nouzilly, France. Electronic address: Yves.Nys@tours.inra.fr.
Yves
Y
Nys
Centre de Biophysique Moléculaire, CNRS UPR 4301, Université d'Orléans, Rue Charles Sadron, 45071 Orléans Cedex 2, France. Electronic address: celine.landon@cnrs-orleans.fr.
Céline
C
Landon
D000595:Amino Acid Sequence; D000818:Animals; D002645:Chickens / Q000378:metabolism*; D021621:Imaging, Three-Dimensional; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D017510:Protein Folding; D023083:beta-Defensins / Q000138:chemical synthesis / Q000737:chemistry*
D023083:beta-Defensins
Antimicrobial Peptides; AvBD; Defensins; Host Defense; NMR; Ovodefensin; Protein Structure; SPPS