Roles of a conserved proline in the internal fusion peptide of Ebola glycoprotein.

The structural determinants underlying the functionality of viral internal fusion peptides (IFPs) are not well understood. We have compared EBOwt (GAAIGLAWIPYFGPAAE), representing the IFP of the Ebola fusion protein GP, and EBOwt (GAAIGLAWIPYFGRAAE) derived from a non-functional mutant with conserved Pro537 substituted by Arg. P537R substitution did not abrogate peptide-membrane association, but interfered with the ability to induce bilayer destabilization. Structural determinations suggest that Pro537 is required to preserve a membrane-perturbing local conformation in apolar environments.