Membrane Fusion via Snare Mimetics Spatially Confined to Intramembrane Domains

Abstract

Membrane fusion is an essential step for many cellular functions. Moreover, cells must be able to confine specific fusion events to certain organelles. Therefore, it is of great interest to demonstrate and study spatially targeted membrane fusion events in vitro. In eukaryotic cells, processes such as neurotransmission, exocytosis and viral infection require membrane fusion and are mediated by rather complex SNARE proteins. Fusion has also been observed using SNARE mimetics such as DNA-lipid conjugates [Chan et al., Biointerphases, 3:FA17, 2008] and lipidated peptides [Pahler et al., Biophysical Journal, 103:2295, 2012]. Here, we demonstrate the fusion of large unilamellar vesicles (LUVs) to a specific location on giant unilamellar vesicles (GUVs). As fusion mediators we use coiled-coil peptide heterodimers or hybridized DNA, both of which are conjugated to lipid anchors. These molecules are spatially confined to phase domains within the GUV membranes. We observe liquid-ordered-specific partitioning for the DNA-lipid conjugate as well as liquid-disordered-specific docking and hemi-fusion events using lipid anchored peptides. This work is pursued within the MaxSynBio consortium which is jointly funded by the Federal Ministry of Education and Research of Germany and the Max Planck Society.