Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10836003 | Peptides | 2010 | 9 Pages |
Abstract
Liver-expressed antimicrobial peptide 2 (LEAP-2) is a 40-residue cationic peptide originally purified from human blood ultrafiltrate. The native peptide contains two disulfide bonds and is unique regarding its primary structure. Its biological role is not known but a previous study showed that chemically synthesized LEAP-2 exhibited in vitro antimicrobial activities against several Gram-positive bacteria. In order to determine its antimicrobial mode of action, we expressed human recombinant LEAP-2 in Escherichia coli. Circular dichroism spectroscopy and nuclear magnetic resonance analyses showed that the structure of the recombinant peptide was identical to that of the chemically synthesized and oxidized LEAP-2, with two disulfide bonds between Cys residues in relative 1-3 and 2-4 positions. Minimal inhibitory concentration (MIC) of the recombinant human LEAP-2 was determined by a conventional broth dilution assay. It was found to be bactericidal against Bacillus megaterium at a 200 μM concentration. Interestingly, the linear LEAP-2 had a greater antimicrobial activity with a MIC value of 12.5 μM, which was comparable to that of magainin2. SYTOX Green uptake was used to assess bacterial membrane integrity. Linear LEAP-2 and magainin2 permeabilized B. megaterium membranes with the same efficiency, whereas oxidized LEAP-2 did not induce stain uptake. Binding of the peptides to plasmid DNA was evaluated by gel retardation assays. The DNA-binding efficacy of linear LEAP-2 was three times higher than that of the peptide-containing disulfide bridges. Altogether, these results show that the secondary structure of human LEAP-2 has a profound impact on its antibacterial activity.
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Authors
Agnès Hocquellet, Benoit Odaert, Charlotte Cabanne, Abdelmajid Noubhani, Wilfrid Dieryck, Gilles Joucla, Caroline Le Senechal, Milen Milenkov, Stéphane Chaignepain, Jean-Marie Schmitter, Stéphane Claverol, Xavier Santarelli, Erick J. Dufourc,