The SNARE family contains more than 60 members in yeast and mammalian cells. These proteins function as mediators in fusion of cellular transport vesicles with the cell membrane. According to the ‘SNARE hypothesis’, the vesicles need to be docked closely and firmly within molecular contact distance of the target bilayer and the cognate SNARE proteins zipper to form a ‘four-helix bundle’ between the two membranes. After the SNARE complex fully zips up, the bilayers are merged. Thus, the intermolecular force within this ‘four-helix bundle’ play critical roles in membrane fusion.
SNAREs alone are sufficient to mediate fusion when reconstituted into a number of model systems including free standing lipid vesicles, supported bilayers and tethered vesicles. However, studies using simpler model systems can provide insight into the fundamental mechanisms of rearrangement of bilayers and result in a better understanding of the biological process.
Because of DNA’s facile synthesis, unique self assembly, and ready programming, short DNA strands can easily assemble into sturdy higher order DNA structures. Thus, we can apply such DNA nanostructures to mimic the function of SNAREs in a strictly controllable system. This will provide us with a better understanding of the intermolecular, both hydrophilic and hydrophobic forces, that directly govern the interaction and fusion of two vesicles, hence determining the kinetics of the membrane fusion process.