Inhibition of Ebola Virus Entry through Biophysical Identification of Functionally Important Residues in the GP2 Fusion Loop

Abstract

Ebola virus (Ebov), is an enveloped filovirus capable of causing severe hemorrhagic fever in humans. Viral entry and membrane fusion is accomplished through rearrangement of the glycoproteins (GP) that stud the outside of the virus particle. Here we have focused our attention on the section of amino acids found in GP called the internal fusion loop (FL). The FL is thought to interact directly with the host membrane allowing for the fusion process to begin. We performed site-directed mutagenesis on the FL to identify key residues required for activity in liposome mixing and pseudo-virus entry. A completely inhibited mutant was identified and a structure in DPC micelles at pH 5.5 was determined using solution NMR spectroscopy.From our previous Ebov FL structures, we hypothesized that the arrangement of hydrophobic residues was key for membrane interaction (1). This was further confirmed through the NMR structure presented here of the inhibited double mutant L529A/I544A FL where the arrangement of hydrophobic residues at the tip of the molecule was significantly disrupted compared to WT. This study shows the importance of the structural arrangement of residues in the FL and their impact on Ebola virus entry.1. Gregory, S. M., Harada, E., Liang, B., Delos, S. E., White, J. M., and Tamm, L. K. (2011). Structure and function of the complete internal fusion loop from Ebolavirus glycoprotein 2. Proc Natl Acad Sci USA 108(27), 11211-6.