Effect of Dengue Fusion Peptide in Langmuir Monolayers

Abstract

Membrane fusion peptides are part of Dengue virus system, serving as a gateway to the virus access into the cell. Studies on the mechanisms of action of these peptides to improve protocols for the treatment and achievement of new drugs to combat the dissemination of the virus are increasingly necessary. The Langmuir technique is very useful to study peptide-lipid interactions. Indeed, the utilization of lipid monolayers allows controlling several physical parameters such as lipid composition, surface pressure and many other parameters of interest. Here we study the interaction of the Dengue Flavivirus fusion peptide (FLAg) with Langmuir monolayers composed of different types of lipids, including POPG, (palmitoyl-oleoyl-phosphatydyl-glycerol). In order to assess peptide maximum insertion pressure (MIP) into the Langmuir model membrane, kinetic measurements were performed. The kinetics of FLAg binding onto the phospholipid monolayer was monitored until the equilibrium surface pressure (Πe) was reached. The MIP was determined by injecting FLAg at different initial surface pressures (Πi) of the lipid monolayers. To investigate the behavior of FLAg in Langmuir monolayers with different lipid composition, we also used in situ infrared spectroscopy (PM-IRRAS). Preliminary results showed an increase in surface pressure during adsorption kinetics experiments with POPG monolayers, revealing an electrostatic affinity that evidences the role of the membrane charge in the fusion process. Furthermore, surface activity of the peptide solution used as the subphase in the absence of lipid monolayers was also measured. PM-IRRAS measurements reveal how the peptide incorporates at the interface of POPG monolayers, showing changes in the spectra, besides indicating characteristic due to the presence of FLAg. Altogether, these data clearly demonstrate that useful information on the binding FLAg to membranes can be obtained by performing measurements of their monolayer binding parameters.