Comparison of lipid vesicle fusion induced by the putative fusion peptide of fertilin (a protein active in sperm-egg fusion) and the NH2-terminal domain of the HIV2 gp41.

A peptide representing a putative fusion domain of fertilin, a sperm surface protein involved in sperm-egg fusion was synthesized. Its interaction with model membranes was characterized and compared with that of a synthetic peptide representing the fusion peptide of HIV-2rod gp41. The fertilin fusion peptide interaction with lipid vesicles is dependent upon the presence of negatively charged lipids in the membrane. Its fusogenic activity does not require PE and is not inhibited by addition of lysolecithin in the medium. These conditions are quite opposite to those obtained with the HIV2 peptide and suggest that the lipid mixing mediated by the two peptides corresponds to two different molecular mechanisms.