Membranes with Decreased Deformability to Study the Kinetics of Fusion Intermediates

Abstract

While the initial protein activation steps involved in influenza membrane fusion have been relatively well resolved, the subsequent lipid rearrangements are much more challenging to study. This is because the formation of lipid intermediates is faster than protein activation and thus masked in kinetic measurements of intact virus. To unmask these intermediates, we have developed methods that utilize target membranes with decreased deformability. By using supported lipid bilayers on silica nanoparticles of a defined diameter we are able to alter the deformability of the target membrane without changing its lipid composition. In conjunction with single-virus fusion kinetics, this allows us to examine the effect of membrane deformability on the kinetics of influenza membrane fusion. Our results show that decreasing target membrane deformability does indeed slow lipid mixing between virus and target. Further extensions to this platform then allow stepwise dissection of how membrane mechanical properties affect influenza membrane fusion.