Fusion pathways of vesicles: A Brownian dynamics simulation

We studied the fusion dynamics of vesicles using a Brownian dynamics simula tion. Amphiphilic molecules spontaneously form vesicles with a bilayer stru cture. Two vesicles come into contact and form a stalk intermediate, in whi ch a necklike structure only connects the outer monolayers, as predicted by the stalk hypothesis. We have found a new pathway of pore opening from sta lks at high temperature: the elliptic stalk bends and contact between the e nds of the arc-shaped stalk leads to pore opening. On the other hand, we ha ve clarified that the pore-opening process at low temperature agrees with t he modified stalk model: a pore is induced by contact between the inner mon olayers inside the stalk. (C) 2001 American Institute of Physics.