Point-like protrusion as a prestalk intermediate in membrane fusion pathway

Area of Science:

• Biophysics
• Cell Biology
• Membrane Dynamics

Background:

• The widely accepted model of membrane fusion identifies the fusion stalk as the initial intermediate of hemifusion.
• Previous models did not fully address the lipid structures that precede hemifusion or their impact on fusion kinetics.

Discussion:

• This study introduces the point-like protrusion as a novel prestalk fusion intermediate.
• Calculations show this protrusion has lower energy than the fusion stalk, suggesting it does not limit fusion rate.
• The energy of the protrusion is dependent on lipid monolayer elastic properties and intermembrane hydration repulsion strength.

Key Insights:

• Identifies a new intermediate in membrane fusion: the point-like protrusion.
• Demonstrates that this prestalk intermediate has lower energy, potentially accelerating membrane merger.
• Integrates the point-like protrusion into the fusion-through-hemifusion model, completing the description of membrane merger.

Outlook:

• Further experimental validation of the point-like protrusion's existence and role.
• Investigating the influence of specific lipid compositions on protrusion formation and fusion kinetics.
• Exploring the broader implications for various biological membrane fusion events.