L. Chernomordik et al., CONTROL OF BACULOVIRUS GP64-INDUCED SYNCYTIUM FORMATION BY MEMBRANE LIPID-COMPOSITION, Journal of virology, 69(5), 1995, pp. 3049-3058
We have investigated the effects of membrane lipid composition on biol
ogical membrane fusion triggered by low pH and mediated by the baculov
irus envelope glycoprotein gp64. Lysolipids, either added exogenously
or produced in situ by phospholipase A2 treatment of cell membranes, r
eversibly inhibited syncytium formation. Lysolipids also decreased the
baculovirus infection rate. In contrast, oleic and arachidonic acids
and mono-olein promoted cell-cell fusion. Membrane lipid composition a
ffected pH-independent processes which followed the low-pH-induced cha
nge in fusion protein conformation. Inhibition and promotion of membra
ne fusion by a number of lipids could not be explained by mere binding
or incorporation into membranes, but rather was correlated with the e
ffective molecular shape of exogenous lipids. Our data are consistent
with the hypothesis that membrane fusion proceeds through highly bent
membrane intermediates (stalks) having a net negative curvature. Conse
quently, inverted cone-shaped lysolipids inhibit and cone-shaped cis-u
nsaturated fatty acids promote stalk formation and, ultimately, membra
ne fusion.