Regensburg 2007 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

BP: Fachverband Biologische Physik

BP 3: Membranes and Interfaces

BP 3.3: Vortrag

Montag, 26. März 2007, 14:45–15:00, H43

What can be learned from a coarse-grained description of membrane fusion? — •Marcus Muller — Institut fuer Theoretische Physik, Georg-August Universitaet, Goettingen

Membrane fusion is a fundamental biological process of importance in fertilization, synaptic release, intracellular traffic, and viral infection. Coarse-grained models can contribute to our understanding of these collective phenomena in membranes [1] that evolve on a few nanometers and milliseconds.

We have carried out simulations of the fusion of tense apposed bilayers formed by amphiphilic molecules. The fusion pathway differs from the common stalk mechanism. Stalks do form between the apposed bilayers, but rather than expand radially to form an axial-symmetric hemifusion diaphragm and they promote the nucleation of small holes in their vicinity. Then, the stalk encircles a hole in one bilayer creating a diaphragm which ruptures to complete the fusion pore. The pathway give rise to mixing between both leaves of the bilayer and allow for transient leakage.

Self-consistent field calculations have be used to explored the role of lipid architecture and tension, and to calculate free energy barriers along the fusion path. We find that (i) successful fusion is found to be severely limited by the architecture of the lipids and that (ii) any mechanism which affects even modestly the line tension of a hole in a membrane affects greatly the ability of that membrane to undergo fusion.

[1] M. Müller, K. Katsov, and M. Schick, Phys. Rep. 434, 113 (2006)