Mechanics of membrane fusion/pore formation

• We review different pathways for fusion and the creation of supported bilayers.
• We focus on the topology and sequence of intermediates in the transition pathways.
• We discuss the pathways’ energetic and biological feasibility.
• We examine the model-dependency of results obtained from computer simulation.
• We predict a stalk shape that is independent of lipid type and external factors.

Lipid bilayers play a fundamental role in many biological processes, and a considerable effort has been invested in understanding their behavior and the mechanism of topological changes like fusion and pore formation. Due to the time- and length-scale on which these processes occur, computational methods have proven to be an especially useful tool in their study. With their help, a number of interesting findings about the shape of fusion intermediates could be obtained, and novel hypotheses about the mechanism of topological changes and the involvement of peptides therein were suggested. In this work, we try to present a summary of these developments together with some hitherto unpublished results, featuring, among others, the shape of stalks and fusion pores, possible modes of action of the influenza HA fusion peptide and the SNARE protein complex, the mechanism of supported lipid bilayer formation by vesicle spreading, and the free energy and transition pathway of the fusion process.