Cholesterol-driven modulation of membrane-membrane interactions by an antimicrobial peptide, NK-2, in phospholipid vesicles.

Antimicrobial peptides (AMPs) are essential components of the innate immune system, demonstrating their antimicrobial effects primarily through the creation of transmembrane pores that result in membrane disruption. Cholesterol within the membrane can significantly affect the interaction between AMPs and the membrane, as it is known to alter both the permeability and elastic properties of the membrane. In this study, we have investigated the influence of cholesterol on the interaction of the AMP, NK-2 with phospholipid vesicles. We prepared giant unilamellar vesicles (GUVs) composed of DOPC-DOPG and Egg PC, varying the cholesterol concentrations, and analyzed them using phase contrast microscopy. The aggregation of vesicles is evident in the phase contrast microscopy observations of GUVs. The aggregation of GUVs with cholesterol ultimately leads to a collapse state, a condition not typically seen in GUVs lacking cholesterol. Furthermore, the aggregation kinetics were determined from the analysis of phase contrast micrographs. This biophysical investigation offers valuable insights into how cholesterol affects the interactions between membranes induced by antimicrobial peptides.