Destabilization of a model membrane by a predicted fusion peptide of fertilin alpha

The subunit alpha of the guinea pig fertilin (previously known as PH-30, an integral membrane protein involved in sperm-egg binding and fusion) is predicted to be a potential fusion protein. The structure of this putative fusion protein was analysed by molecular modeling and we have found a peptidic sequence of 17 residues (D-83-P-99) organized in helix that inserts obliquely in lipid phases. The effect of this synthesized peptide was studied on a model membrane by P-31 NMR and light scattering, It appears to increase the size of lipid vesicles and induces structural modifications. We interpret these observations as a destabilization of the lipid organization by this peptide because of its tilted insertion in phospholipid layers. This destabilization could favor membrane fusion.