Calcium-dependent conformational changes of membrane-bound Ebola fusion peptide drive vesicle fusion.

The fusogenic subdomain of the Ebola virus envelope glycoprotein is an internal sequence located ca. 20 residues downstream the N-terminus of the glycoprotein transmembrane subunit. Partitioning of the Ebola fusion peptide into membranes containing phosphatidylinositol in the absence of Ca2+ stabilizes an alpha-helical conformation, and gives rise to vesicle efflux but not vesicle fusion. In the presence of millimolar Ca2+ the membrane-bound peptide adopts an extended beta-structure, and induces inter-vesicle mixing of lipids. The peptide conformational polymorphism may be related to the flexibility of the virus-cell intermembrane fusogenic complex.