Structure and mode of action of the antimicrobial peptide arenicin
Résumé
The solution structure and the mode of action of arenicin isoform 1, an antimicrobial peptide with a unique 18-residue loop structure, from the lugworm Arenicola marina were elucidated here. Arenicin folds into a two-stranded anti-parallel β-sheet. It exhibits high antibacterial activity at 37°C and 4°C against Gram-negative bacteria, including polymyxin B resistant Proteus mirabilis. Bacterial killing occurs within minutes and is accompanied by membrane permeabilisation, membrane detachment, and release of cytoplasm. Interaction of arenicin with reconstituted membranes that mimic the lipopolysaccharide-containing outer membrane or the phospholipid-containing plasma membrane of Gram-negative bacteria exhibited no pronounced lipid specificity. Arenicin-induced current fluctuations in planar lipid bilayers correspond to the formation of short lived heterogeneously structured lesions. Our data strongly suggest that membrane interaction plays a pivotal role in the antibacterial activity of arenicin.
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