Center for Functional Nanomaterials Seminar

The importance of membrane fusion in biological systems hardly needs to be emphasized. It plays a central role in trafficking within the cell, in the transport of materials out of the cell, as in synaptic vesicles, and in the release of endosome-enclosed external material into the cell, as in viral infection. We use a microscopic model of amphiphilic chains (lipids) in hydrophilic solvent (water) to study this process. The combination of Monte Carlo simulations and Self-consistent Field Theory allows us to determine structural and energetic properties of intermediates and transition states involved in our fusion model. In contrast to a common belief that fusion proceeds through a sequence of axially symmetric states, we find a family of new mechanisms, which break the axial symmetry and involve activation barriers lower than those involved in the standard mechanism. Success of the complete fusion
is severely limited by lipid architecture. We also predict that fusion is accompanied by transient leakage and formation of long living "flickering" fusion pores, in agreement with experimental observations.