Recombinant expression and solution structure of antimicrobial peptide aurelin from jellyfish Aurelia aurita

Aurelin is a 40-residue cationic antimicrobial peptide isolated from the mezoglea of a scyphoid jellyfish Aurelia aurita. Aurelin and its N-15-labeled analogue were overexpressed in Escherichia colt and purified. Antimicrobial activity of the recombinant peptide was examined, and its spatial structure was studied by NMR spectroscopy. Aurelin represents a compact globule, enclosing one 3(10)-helix and two alpha-helical regions cross-linked by three disulfide bonds. The peptide binds to anionic lipid (POPC/DOPG, 3:1) vesicles even at physiological salt concentration, it does not interact with zwitterionic (POPC) vesicles and interacts with the DPC micelle surface with moderate affinity via two alpha-helical regions. Although aurelin shows structural homology to the BgK and ShK toxins of sea anemones, its surface does not possess the "functional dyad" required for the high-affinity interaction with the K+-channels. The obtained data permit to correlate the modest antibacterial properties and membrane activity of aurelin. (C) 2012 Elsevier Inc. All rights reserved.