2lg5
NMR structure of Chicken AvBD2 defensin
Structural highlights
FunctionGLL2_CHICK Potent antibacterial activity against the Gram-negative bacterium E.coli ML-35, and against the Gram-positive bacterium L.monocytogenes EGD. Lacks antifungal activity against C.albicans.[1] Publication Abstract from PubMedNumerous beta-defensins have been identified in birds, and the potential use of these peptides as alternatives to antibiotics has been proposed, in particular to fight antibiotic-resistant and zoonotic bacterial species. Little is known about the mechanism of antibacterial activity of avian beta-defensins, and this study was carried out to obtain initial insights into the involvement of structural features or specific residues in the antimicrobial activity of chicken AvBD2. Chicken AvBD2 and its enantiomeric counterpart were chemically synthesized. Peptide elongation and oxidative folding were both optimized. The similar antimicrobial activity measured for both L- and D-proteins clearly indicates that there is no chiral partner. Therefore, the bacterial membrane is in all likelihood the primary target. Moreover, this work indicates that the three-dimensional fold is required for an optimal antimicrobial activity, in particular for gram-positive bacterial strains. The three-dimensional NMR structure of chicken AvBD2 defensin displays the structural three-stranded antiparallel beta-sheet characteristic of beta-defensins. The surface of the molecule does not display any amphipathic character. In light of this new structure and of the king penguin AvBD103b defensin structure, the consensus sequence of the avian beta-defensin family was analyzed. Well conserved residues were highlighted, and the potential strategic role of the lysine 31 residue of AvBD2 was emphasized. The synthetic AvBD2-K31A variant displayed substantial N-terminal structural modifications and a dramatic decrease in activity. Taken together, these results demonstrate the structural as well as the functional role of the critical lysine 31 residue in antimicrobial activity. Initial insights into structure-activity relationships of avian defensins.,Derache C, Meudal H, Aucagne V, Mark KJ, Cadene M, Delmas AF, Lalmanach AC, Landon C J Biol Chem. 2012 Mar 2;287(10):7746-55. Epub 2011 Dec 27. PMID:22205704[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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