Real-Time Analysis of Individual Ebola Virus Glycoproteins Reveals Pre-Fusion, Entry-Relevant Conformational Dynamics

• Published in: Viruses Vol. 12; no. 1; p. 103
• Main Authors: Durham, Natasha D, Howard, Angela R, Govindan, Ramesh, Senjobe, Fernando, Fels, J Maximilian, Diehl, William E, Luban, Jeremy, Chandran, Kartik, Munro, James B
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 15.01.2020; MDPI
• Subjects: Acquired immune deficiency syndrome; AIDS; Antibodies; Antibodies, Neutralizing - immunology; Antibodies, Viral - immunology; Binding sites; C1 protein; Cathepsins; Cell culture; conformational dynamics; Ebola virus; Ebolavirus; Ebolavirus - chemistry; Ebolavirus - physiology; envelope glycoprotein; Epidemics; Fluorescence Resonance Energy Transfer; Glycoproteins; HEK293 Cells; HIV; Human immunodeficiency virus; Humans; Infections; Membrane Fusion; Membranes; Niemann-Pick disease; Npc1 protein; Plasmids; Protein Binding; Protein Conformation; Proteins; Proteolysis; Reagents; single-molecule fret; Viral Envelope Proteins - chemistry; Viral Fusion Proteins - chemistry; Virions; virus entry; Virus Internalization; Viruses; United States > US; Germany; Ebola virus; single-molecule FRET; virus entry; conformational dynamics; envelope glycoprotein
• ISSN: 1999-4915; 1999-4915
• DOI: 10.3390/v12010103

The Ebola virus (EBOV) envelope glycoprotein (GP) mediates the fusion of the virion membrane with the membrane of susceptible target cells during infection. While proteolytic cleavage of GP by endosomal cathepsins and binding of the cellular receptor Niemann-Pick C1 protein (NPC1) are essential steps for virus entry, the detailed mechanisms by which these events promote membrane fusion remain unknown. Here, we applied single-molecule Förster resonance energy transfer (smFRET) imaging to investigate the structural dynamics of the EBOV GP trimeric ectodomain, and the functional transmembrane protein on the surface of pseudovirions. We show that in both contexts, pre-fusion GP is dynamic and samples multiple conformations. Removal of the glycan cap and NPC1 binding shift the conformational equilibrium, suggesting stabilization of conformations relevant to viral fusion. Furthermore, several neutralizing antibodies enrich alternative conformational states. This suggests that these antibodies neutralize EBOV by restricting access to GP conformations relevant to fusion. This work demonstrates previously unobserved dynamics of pre-fusion EBOV GP and presents a platform with heightened sensitivity to conformational changes for the study of GP function and antibody-mediated neutralization.