Real-time monitoring of interactions between Ebola fusion peptide and solid-supported phospholipid membranes: Effect of peptide concentration and layer geometry

The pathogenesis of the Ebola virus which leads to a severe hemorrhagic fever in hosts is a very complex process which is not completely understood. Glycoproteins of the viral envelope are believed to play a crucial role in receptor binding and subsequently in fusion of the virus with the target cells of the host. As a result, the virus enters the cells and replicates. This process causes further cytopathic, and pathological reactions in the host's body. To gain further insights into the fusogenic interactions of the virus with cell membranes, we used well-controlled simple biomimetic systems, consisting of solid-supported phospholipid layers together with a small sequence of the viral glycoprotein (EBO17), which is believed to be the most important part responsible for viral pathogenesis. We monitor the real-time interaction of a EBO17 peptide sequence from the Ebola virus with dipalmitoylphosphatidylcholine (DMPC) phospholipid membranes using quartz crystal microbalance with dissipation monitoring (QCM-D) as a label-free method. In particular, we focus on the influence of the concentration of the peptide and the lipid layer geometry on the disrupting mechanism of the EBO17 peptide. Results indicate that for 2D supported lipid bilayers, low peptide concentrations induce a small, but detectable change in layer stability due to the presence of an α-helix configuration of the peptide. With large peptide concentrations, the peptide acquires a β-sheet configuration and no significant layer changes can be observed. A different mechanism is responsible for the interaction of the EBO17 peptides with the more complex 3D supported vesicle layers, for which a concentration-dependent trend can be observed leading to thicker lipid layers. Complementary analysis of the lipids' main phase transition evidences the differences induced in layer organization on the two layer geometries. These results confirm the importance of the interplay between lipid layer geometry and related peptide organization as an essential marker in peptide activity.