X-ray diffraction study of feline leukemia virus fusion peptide and lipid polymorphism

The structural effects of the fusion peptide of feline leukemia virus (FeLV ) on the lipid polymorphism of N-methylated dioleoylphosphatidylethanolamin e were studied using a temperature ramp with sequential X-ray diffraction, This peptide, the hydrophobic amino-terminus of p15E, has been proven to be fusogenic and to promote the formation of highly curved, intermediate stru ctures on the lamellar liquid-crystal to inverse hexagonal phase transition pathway. The FeLV peptide produces marked effects on the thermotropic meso morphic behaviour of MeDOPE, a phospholipid with an intermediate spontaneou s radius of curvature, The peptide is shown to reduce the lamellar repeat d istance of the membrane prior to the onset of an inverted cubic phase. This suggests that membrane thinning may play a role in peptide-induced membran e fusion and strengthens the link between the fusion pathway and inverted c ubic phase formation, The results of this study are interpreted in relation to models of the membrane fusion mechanism. (C) 1999 Federation of Europea n Biochemical Societies.