CRYSTAL-STRUCTURE OF THE EBOLA-VIRUS MEMBRANE-FUSION SUBUNIT, GP2, FROM THE ENVELOPE GLYCOPROTEIN ECTODOMAIN

We have determined the structure of GP2 from the Ebola virus membrane fusion glycoprotein by X-ray crystallography. The molecule contains a central triple-stranded coiled coil followed by a disulfide-bonded loo p homologous to an immunosuppressive sequence in retroviral glycoprote ins, which reverses the chain direction and connects to an a helix pac ked antiparallel to the core helices. The structure suggests that fusi on peptides near the N termini form disulfide-bonded loops at one end of the molecule and that the C-terminal membrane anchors are at the sa me end. In this conformation, GP2 could both bridge two membranes and facilitate their apposition to initiate membrane fusion. We also find a heptad irregularity like that in low-pH-induced influenza HA2 and a solvent ion trapped in a coiled coil like that in retroviral TMs.