Initial Insights into Structure-Activity Relationships of Avian Defensins

Abstract

Background: Avian defensins are antimicrobial peptides of a bird's immunity. Results: The target of chicken AvBD2 defensin is not chiral. Its structure is not amphipathic. The reduced and AvBD2-K31A forms dramatically decrease antibacterial activity. Conclusion: AvBD2 may disrupt the bacterial membrane through a nonchiral, nonspecific interaction. Significance: Knowledge of the structure-function relationships of avian defensins is a prerequisite for their use as alternatives to antibiotics.

Three-dimensional NMR Structure of Hen Egg Gallin (Chicken Ovodefensin) Reveals a New Variation of the β-Defensin Fold

“…The determination of the first tridi-mensional NMR structures of king penguin AvBD103b and chicken AvBD2 defensins showed the disulfide bridge motif typical of ␤-defensins (i.e. C1-C5/C2-C4/C3-C6) (16,17), thus corroborating this terminology. Last, AvBDs generally possess antimicrobial activities against various microorganisms, including Gram-positive and Gram-negative bacteria as well as fungi (18 -21).…”

“…MICs were 0.84, 1.23, and 2.00 M, respectively, for the non-pathogenic ATCC 25922 and for the pathogenic CFT073 and BEN3578 E. coli strains. 16 . Structure Calculations-NOE assignments were progressively introduced during the iterative process of ARIA and manually validated between each run until complete assignment of the NOESY map.…”

Towards the Simplification of Protein Synthesis: Iterative Solid‐Supported Ligations with Concomitant Purifications

“…The standard protocol was applied to the d enantiomer of the chicken beta-defensin (AvBD2; 36 amino acids), with acetamidomethyl (Acm) protecting groups on its six cysteine thiol side-chains, for biological evaluation. [26] The solid-supported synthesis of the native l-AvBD2 proved to be quite challenging, [27] and we had to rigorously optimize the elongation conditions, to include three pseudoproline dipeptides together with a polar solid support. [28] Unfortunately, d-pseudoproline or the equivalent building blocks are not readily available so far, and therefore standard protective groups were used for the synthesis of d-AvBD2-(Acm) 6 .…”

AvBD1 nucleotide polymorphisms, peptide antimicrobial activities and microbial colonisation of the broiler chicken gut

“…Modelling of the AvBD1 molecules indicated their native folded structures to be comparable, with each displaying a three-stranded antiparallel β-sheet structure. In contrast to AvBD2 [ 34 ], they were all predicted a short N-terminal helical segment, the importance of which in bacterial killing, was supported by the CD spectra data. All three molecules were projected to display externalisation of positively charged and hydrophobic residues with the localisation of positively charged amino acids R30, K27, R2 and K3, lending support to a strong electrostatic interaction of the defensin molecules with anionic bacterial membranes.…”