Activity of a novel-designed antimicrobial peptide and its interaction with lipids

A new antimicrobial peptide l‐RW containing double amphipathic binding sequences was designed, and its biological activities were investigated in the present study. L‐RW showed antibacterial activity against several bacterial strains but low cytotoxicity to mammalian cells and low hemolytic activity to red blood cells, which makes it a potential and promising peptide for further development. Microscale thermophoresis (MST), a new technique, was applied to study the antimicrobial peptide–lipid interaction for the first time, which examined the binding affinities of this new antimicrobial peptide to various lipids, including different phospholipids, mixture lipids and bacterial lipid extracts. The results demonstrated that l‐RW bound preferentially to negatively charged lipids over neutral lipids, which was consistent with the biological activities, revealing the important role of electrostatic interaction in the binding process. L‐RW also showed higher binding affinity for lipid extract from Staphyloccocus aureus compared with Pseudomonas aeruginosa and Escherichia coli, which were in good agreement with the higher antibacterial activity against S. aureus than P. aeruginosa and E. coli, suggesting that the binding affinity is capable to predict the antibacterial activity to some extent. Additionally, the binding of l‐RW to phospholipids was also performed in fetal bovine serum solution by MST, which revealed that the components in biological solution may have interference with the binding event. The results proved that MST is a useful and potent tool in antimicrobial peptide–lipid interaction investigation. Copyright © 2015 European Peptide Society and John Wiley & Sons, Ltd. FITC‐l‐RW showed higher binding affinity for the lipid extract from Staphyloccocus aureus compared with those from Pseudomonas aeruginosa and Escherichia coli, which were in good agreement with higher antibacterial activity against S. aureus than P. aeruginosa and E. coli. The consistence between antibacterial activity and binding affinity suggests that binding is a significant process in peptide mechanism, and the binding affinity partly explains the biological activity of the designed peptide.