Biophysical Society Thematic Meeting| Padova 2019

Quantitative Aspects of Membrane Fusion and Fission

Poster Abstracts

46-POS Board 46 FUSION EFFICIENCY IN MODEL SYSTEMS: A QUANTITATIVE COMPARISON Tom Robinson ; Reinhard Lipowsky 1 ; Rumiana Dimova 1 ; 1 Max Planck Institute of Colloids and Interfaces, Theory and Bio-Systems, Potsdam, Brandenburg, Germany Biological membrane fusion is essential for cellular functions such as neurotransmission and exocytosis. The fusion of biomembranes is also involved in viral infection. Understanding the biophysical mechanisms underpinning membrane fusion is vital to unravel this fundamental process. In nature, the SNARE complex governs membrane fusion in eukaryotes. Model membrane systems are powerful tools which enable us to isolate specific factors and study their influence on fusion. Different studies have examined membrane fusion in such systems using SNAREs and SNARE-mimetics.Lipid vesicles are one of the most commonly used fusion models in the literature and in particular LUV-LUV fusion. Here, we have utilized giant and large unilamellar vesicles (GUVs and LUVs) as our model system and we show fusion via four different systems. The first being protein-free, using a pure lipid system, exhibiting high fusion efficiency [Biophys. J. 116:79, 2019]. The second is based on lipidated-DNA and shows low fusion efficiency with negligible full fusion events. The third uses lipidated-peptides (in collaboration with the Janshoff group) and while full fusion events were detected, the efficiency was low [Robinson, et al., submitted]. The final system involved reconstituted SNARE proteins (in collaboration with the Steinham lab) and displayed high fusion efficiency which proceeds to full fusion and content mixing. With all of these systems we quantitatively compare the fusion efficiency between LUVs and GUVs with results found in the literature using alternative model systems. We discuss the differences in reported fusion efficiencies, demonstrate the importance of the choice of model membrane system used to investigate fusion and highlight the pitfalls, which could lead to overestimates of fusion efficiencies.This work is performed within the MaxSynBio consortium which is jointly funded by the Federal Ministry of Education and Research of Germany and the Max Planck Society.

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