Role of Lipid Environment in the Pore-Forming Activity of Cecropin A

Abstract

Cecropin A (CecA) is a well-known antimicrobial peptide produced by Hyalophore cecropia. It was found that cecropin A forms ion channels of different conductance and selectivity in planar lipid bilayers in the presence of negatively charged DOPS. Here the pore-forming activity of CecA in lipid bilayer of different lipid composition formed by the Montall and Muller technique in the absence and in the presence of alkaloids was studied. We found that one-side addition of CecA up to 5 µM led to the destabilization of lipid bilayers composed of POPC:POPG (50:50 mol %) or POPC:POPE:POPG (25:25:50 mol %). At the same time 2 µM of CecA induced the step-like current fluctuations corresponding to the openings and closures of transmembrane pores in POPC:TOCL – membranes (50:50 mol %). Increasing of CecA concentration up to 5 µM enhanced the macroscopic conductance. Introduction of piperine or capsaicin to the membrane bathing solution up to 400 µM caused dramatic reduction in multichannel conductance induced by CecA. Using differential scanning microcalorimetry we showed that piperine and capsaicin decreased the maximum temperature of the main transition of DPPC at molar ratio to lipid of 1:10 on 3.6 and 5.7 °C respectively. Analyzing the data we suggested that regulation of CecA induced macroscopic conductance is due to the changes in the elastic properties of the membrane at alkaloid adsorption. The study was supported by the Russian Foundation of Science (# 19-14-00110) and Russian Foundation of Basic Research (# 18-34-20047)