Molecular Mechanism of Action of β-Hairpin Antimicrobial Peptide Arenicin: Oligomeric Structure in Dodecylphosphocholine Micelles and Pore Formation in Planar Lipid Bilayers

Abstract

The membrane-active, cationic, β-hairpin peptide, arenicin, isolated from marine polychaeta Arenicola marina exhibits a broad spectrum of antimicrobial activity. The peptide in aqueous solution adopts the significantly twisted β-hairpin conformation without pronounced amphipathicity. To assess the mechanism of arenicin action, the spatial structure and backbone dynamics of the peptide in membrane-mimicking media and its pore-forming activity in planar lipid bilayers were studied. The spatial structure of the asymmetric arenicin dimer stabilized by parallel association of N-terminal strands of two β-hairpins was determined using triple-resonance nuclear magnetic resonance (NMR) spectroscopy in dodecylphosphocholine (DPC) micelles. Interaction of arenicin with micelles and its oligomerization significantly decreased the right-handed twist of the β-hairpin, increased its amphipathicity, and led to stabilization of the peptide backbone on a picosecond to nanosecond time scale. Relaxation enhancement induced by water-soluble (Mn(2+)) and lipid-soluble (16-doxylstearate) paramagnetic probes pointed to the dimer transmembrane arrangement. Qualitative NMR and circular dichroism study of arenicin-2 in mixed DPC/1,2-dioleoyl-sn-glycero-3-phosphoglycerol bicelles, sodium dodecyl sulfate micelles, and lipid vesicles confirmed that a similar dimeric assembly of the peptide was retained in membrane-mimicking systems containing negatively charged lipids and detergents. Arenicin-induced conductance was dependent on the lipid composition of the membrane. Arenicin low-conductivity pores were detected in the phosphatidylethanolamine-containing lipid mixture, whereas the high-conductivity pores were observed in an exclusively anionic lipid system. The measured conductivity levels agreed with the model in which arenicin antimicrobial activity was mediated by the formation of toroidal pores assembled of two, three, or four β-structural peptide dimers and lipid molecules. The structural transitions involved in arenicin membrane-disruptive action are discussed.

Sea Anemone Peptide with Uncommon β-Hairpin Structure Inhibits Acid-sensing Ion Channel 3 (ASIC3) and Reveals Analgesic Activity

“…We examined all resolved structures of short venom peptides to find possible similarities. We searched the PDB for molecules with folds composed of only ␤-hairpins and found a small number of structures: 3 peptides from spiders, 1 peptide from cones (30 -32), 3 antimicrobial peptides, and 1 hormonelike peptide that suppresses the growth of insects (33)(34)(35)(36).…”

Analysis of Synergistic Effects of Antimicrobial Peptide Arenicin-1 and Conventional Antibiotics

“…The peptide consists of 21 amino acid residues, two of which are cysteines and form a disulfide bond [6]. Due to the high content of basic amino acid residues and compact β-hairpin amphiphilic structure [7], the peptide can rapidly disrupt the integrity of the bacterial membrane by acting through "toroidal pore" formation [11], and thereby increasing its permeability for various substances [3]. Thus, arenicin-1 can increase the effectiveness of drugs that affect intracellular targets.…”

Strand Length-Dependent Antimicrobial Activity and Membrane-Active Mechanism of Arginine- and Valine-Rich β-Hairpin-Like Antimicrobial Peptides

“…Generally, a ␤-hairpin contains one or two disulfide bonds to cyclize the peptide chain. Previous studies have reported that amphipathic ␤-hairpin-like structures or two-strand ␤-sheet conformations had potent antimicrobial properties and high cell selectivity (9,24,35).…”