Curvature-Induced Membrane Remodeling by the Cell-Penetrating Peptide Pep-1.

The cell-penetrating peptide Pep-1 interacts with lipid membranes through combined electrostatic and hydrophobic forces, yet the structural details of its membrane remodeling activity remain unclear. Using atomic force microscopy (AFM), we examined how Pep-1 perturbs supported lipid bilayers of varying composition and geometry. In zwitterionic POPC bilayer patches, Pep-1 preferentially targeted patch boundaries, where lipid packing is less constrained, leading to edge erosion and detergent-like disintegration. Incorporation of anionic POPS enhanced peptide binding and localized disruption, giving rise to elevated annular rims, holes, and peptide-lipid aggregates. In cholesterol-containing POPC bilayer patches, Pep-1 induced extensive surface reorganization marked by protruded, ridge-like features, consistent with lipid redistribution and curvature generation. In continuous POPC/POPS bilayers lacking free edges, Pep-1 formed discrete, flower-like protrusions that coalesced into an interconnected network of thickened peptide-rich domains. These findings reveal composition-dependent remodeling pathways in which Pep-1 destabilizes, reorganizes, or curves membranes according to their mechanical and electrostatic properties, providing new insight into peptide-membrane interactions relevant to cell-penetrating peptide translocation.