Dengue Virus Fusion Peptide Promotes Hemifusion Formation by Disordering the Interfacial Region of the Membrane.

Membrane fusion is the first step in the infection process of the enveloped viruses. Enveloped viruses fuse either at the cell surface or enter the cell through endocytosis and transfer their internal genetic materials by fusing with the endosomal membrane at acidic pH. In this work, we have evaluated the effect of the Dengue virus fusion peptide (DENV FP) on the polyethylene glycol (PEG)-mediated lipid mixing of vesicles (hemifusion formation) at pH 5 and pH 7.4 with varying cholesterol concentrations. We have demonstrated that the DENV FP promotes hemifusion formation during the fusion of small unilamellar vesicles (SUVs) mainly at pH 5.0. Moreover, the fusion process demonstrates a strong correlation between fusogenicity and the amount of membrane cholesterol. We have further evaluated the partitioning ability of the peptide in three different membranes at pH 5.0 and pH 7.4. The fusogenic ability of the peptide at pH 5.0 is associated with the composition-dependent binding affinity of the peptide to the membrane. The depth-dependent fluorescence probes are used to evaluate membrane organization and dynamics utilizing steady-state and time-resolved fluorescence spectroscopic techniques. Our results show that the DENV FP promotes hemifusion formation by fluidizing the interfacial region of the membrane.