Electrochemical and AFM study of the interaction of recombinant human cathelicidin LL-37 with various supported bilayer lipid membranes

The overuse of antibiotics is strongly associated with the development of the bacterial resistance which means that novel antimicrobial agents with different mode of action must be prepared. Antimicrobial peptides (AMP) can serve as almost an ideal candidate for the new generation of antimicrobial compounds. In this work the interactions of recombinantly prepared cathelicidin LL-37 towards various types and mixtures of supported bilayer lipid membranes (s-BLMs) are studied by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and atomic force microscopy (AFM). All of these methods have approved excellent efficiency of LL-37 towards membranes that are typical for prokaryotic organisms composed mainly of phosphatidylglycerol and lipid A. On the contrary, almost zero activity towards phosphatidylcholine membranes that are more frequently found in the structure of eukaryotic organisms was observed. A 'carpet model' where the peptides interact primarily with the lipid head groups, have been proved as a mode of LL-37 action. This finding is based on the results obtained by CV and EIS techniques and was revealed by the visualization of the electrode surface by AFM technique.