Antimicrobial Peptide-Induced Remodeling of Supported Lipid Bilayer Visualized by Atomic Force Microscopy

Antimicrobial peptides (AMPs) play a crucial role in the innate immune systems of various organisms. These peptides interact with lipid membranes through multiple mechanisms and affect the membrane extensively in various ways, including minor defect formation, nanosized pore formation, and microscale membrane lysis. The interactions between AMPs and cell membranes have been extensively studied using different biochemical assays, they are thought to kill pathogens by targeting the cell membrane. However, the detailed mechanisms behind membrane destabilization remain unclear. Here, we used atomic force microscopy (AFM) to explore the effects of AMPs CM15 and truncated melittin (Mel (2-9)) on E. coli polar lipid bilayers. CM15 is a hybrid peptide composed of cecropin-A from silk moth and melittin from bee venom. Truncated melittin used in this study is the part of melittin in CM15 peptide. Direct imaging of supported lipid bilayers exposed to various concentrations of the CM15 peptide revealed significant membrane remodeling. Lower concentrations yielded pore formation, while higher yielded complete membrane disruption. Time dependent dynamics of pore formation were observed. Interestingly, our investigation with Mel (2-9) also showed a clear remodeling effect on E. coli lipid supported bilayers. Our study sheds light on how CM15 interacts with a supported lipid bilayer.