Fusion Pores Live on the Edge

Area of Science:

• Biophysics
• Cell Biology
• Molecular Dynamics

Background:

• Biological transmission of vesicular content relies on fusion pore opening.
• Fusion pores in docked vesicles often form at the vertex of flat contact zones.

Purpose of the Study:

• To model and understand the forces governing fusion pore formation at vesicle contact zone edges.
• To investigate the role of contact angle in determining fusion pore size.

Main Methods:

• Coarse-grained molecular simulations.
• Application of elastic theory to model vesicle-vesicle interactions.
• Analysis of fusion pore size dependence on contact angle.

Main Results:

• Fusion pores exhibit a direct attraction towards the vertex of the contact zone.
• The equilibrium size of the vertex pore is strongly dependent on the apparent contact angle.
• Larger contact angles lead to substantially increased vertex pore size.

Conclusions:

• Cellular membrane fusion machinery actively increases contact zone area and angle, thereby driving fusion pore expansion.
• The fusion machinery can remotely control fusion pore size through geometric effects, not solely via fusion proteins.