Structure and membrane interactions of chionodracine, a piscidin-like antimicrobial peptide from the icefish Chionodraco hamatus

• A novel antimicrobial peptide Cnd was studied by TEM, fluorescence and NMR.
• Cnd interacts with cell membranes and disrupts both inner and outer membranes.
• Cnd showed a preference for negatively charged lipid membranes.
• Cnd in DPC micelles adopts a canonical amphipathic helix.
• Cnd can be used as a template for developing new antimicrobial agents.

Chionodracine (Cnd) is a 22-residue peptide of the piscidin family expressed in the gills of the Chionodraco hamatus as protection from bacterial infections. Here, we report the effects of synthetic Cnd on both Psychrobacter sp. TAD1 and Escherichia coli bacteria, as well as membrane models. We found that Cnd perforates the inner and outer membranes of Psychrobacter sp. TAD1, making discrete pores that cause the cellular content to leak out. Membrane disruption studies using intrinsic and extrinsic fluorescence spectroscopy revealed that Cnd behaves similarly to other piscidins, with comparable membrane partition coefficients. Membrane accessibility assays and structural studies using NMR in detergent micelles show that Cnd adopts a canonical topology of antimicrobial helical peptides, with the hydrophobic face toward the lipid environment and the hydrophilic face toward the bulk solvent. The analysis of Cnd free energy of binding to vesicles with different lipid contents indicates a preference for charged phospholipids and a more marked binding to native E. coli extracts. Taken with previous studies on piscidin-like peptides, we conclude that Cnd first adsorbs to the membrane, and then forms pores together with membrane fragmentation. Since Cnd has only marginal hemolytic activity, it constitutes a good template for developing new antimicrobial agents.

Dividing cells with leakage of cellular contents after 10 min of treatment with Cnd.Figure optionsDownload high-quality image (378 K)Download as PowerPoint slide