Pathway of Membrane Fusion with Two Tension-Dependent Energy Barriers

TLDR

Dissipative particle dynamics simulations are employed to study bilayer membrane fusion. The authors introduce new DPD parameters that generate an energy barrier for lipid flips between adhering membranes and monitor numerous fusion events between a vesicle and a planar membrane. Fusion time scales vary exponentially with membrane tension, indicating a ~10 kBT barrier for intermembrane lipid flips and a second size‑dependent barrier for nucleating a small hemifused patch.

Abstract

Fusion of bilayer membranes is studied via dissipative particle dynamics (DPD) simulations. A new set of DPD parameters is introduced which leads to an energy barrier for flips of lipid molecules between adhering membranes. A large number of fusion events is monitored for a vesicle in contact with a planar membrane. Several time scales of the fusion process are found to depend exponentially on the membrane tension. This implies an energy barrier of about 10k(B)T for intermembrane flips and a second size-dependent barrier for the nucleation of a small hemifused membrane patch.