Membrane tension increases fusion efficiency of model membranes in the presence of SNAREs.
Kliesch, Torben-Tobias ; Dietz, Jörn ; Turco, Laura ; Halder, Partho ; Polo, Elena ; Tarantola, Marco ; Jahn, Reinhard ; Janshoff, Andreas
Citable Link (URL):http://resolver.sub.uni-goettingen.de/purl?gs-1/14824
The large gap in time scales between membrane fusion occurring in biological systems during neurotransmitter release and fusion observed between model membranes has provoked speculations over a large number of possible factors that might explain this discrepancy. One possible reason is an elevated lateral membrane tension present in the presynaptic membrane. We investigated the tension-dependency of fusion using model membranes equipped with a minimal fusion machinery consisting of syntaxin 1, synaptobrevin and SNAP 25. Two different strategies were realized; one based on supported bilayers and the other one employing sessile giant liposomes. In the first approach, isolated patches of planar bilayers derived from giant unilamellar vesicles containing syntaxin 1 and preassembled SNAP 25 (ΔN-complex) were deposited on a dilatable PDMS sheet. In a second approach, lateral membrane tension was controlled through the adhesion of intact giant unilamellar vesicles on a functionalized surface. In both approaches fusion efficiency increases considerably with lateral tension and we identified a threshold tension of 3.4 mN m(-1), at which the number of fusion events is increased substantially.
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