Modelling study of dimerization in mammalian defensins.
BACKGROUND
Defensins are antimicrobial peptides of innate immunity functioning by non-specific binding to anionic phospholipids in bacterial membranes. Their cationicity, amphipathicity and ability to oligomerize are considered key factors for their action. Based on structural information on human beta-defensin 2, we examine homologous defensins from various mammalian species for conserved functional physico-chemical characteristics.


RESULTS
Based on homology greater than 40%, structural models of 8 homologs of HBD-2 were constructed. A conserved pattern of electrostatics and dynamics was observed across 6 of the examined defensins; models backed by energetics suggest that the defensins in these 6 organisms are characterized by dimerization-linked enhanced functional potentials. In contrast, dimerization is not energetically favoured in the sheep, goat and mouse defensins, suggesting that they function efficiently as monomers.


CONCLUSIONS
Beta-defensin 2 from some mammals may work as monomers while those in others, including humans, work as oligomers. This could potentially be used to design human defensins that may be effective at lower concentrations and hence have therapeutic benefits.
Suresh
Anita
A
Biomolecular Modelling and Design Group, Bioinformatics Institute, 30 Biopolis Street, #07-01 Matrix, Singapore 138671. anita@bii.a-star.edu.sg
Verma
Chandra
C
D000818:Animals; D002412:Cations; D002462:Cell Membrane / Q000378:metabolism; D003198:Computer Simulation; D023082:Defensins / Q000737:chemistry* / Q000378:metabolism; D019281:Dimerization; D006801:Humans; D008322:Mammals; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D020836:Protein Structure, Quaternary; D016415:Sequence Alignment; D023083:beta-Defensins / Q000737:chemistry / Q000235:genetics
D002412:Cations; C106641:DEFB4A protein, human; D023082:Defensins; D023083:beta-Defensins