Phosphatidylcholine Membrane Fusion Is pH-Dependent.

Area of Science:

• Biophysics
• Cell Biology
• Biochemistry

Background:

• Membrane fusion is vital for cellular functions and viral entry.
• Specialized proteins drive membrane fusion, requiring significant energy for lipid rearrangement.
• The mechanical properties of lipid bilayers are critical for overcoming fusion energy barriers.

Purpose of the Study:

• To investigate the effect of environmental pH on membrane fusion rates.
• To analyze how pH-induced changes in lipid bilayer properties influence fusion energy barriers.
• To understand the role of spontaneous curvature in pH-mediated fusion.

Main Methods:

• Utilized a continual model to simulate membrane fusion dynamics.
• Investigated lipid bilayers composed of zwitterionic lipids.
• Examined pH variations within the physiological range (4.0-7.5).

Main Results:

• Environmental pH changes notably affect membrane fusion rates, even for zwitterionic lipid membranes.
• Spontaneous curvature of the lipid monolayer is identified as the key factor determining the fusion energy barrier height.
• pH-induced rearrangements in the polar lipid headgroups alter spontaneous curvature.

Conclusions:

• Environmental pH is a critical, often overlooked, factor in membrane fusion processes.
• Modulation of spontaneous curvature by pH influences the energetics of membrane fusion.
• Findings are relevant for understanding enveloped virus fusion with host cell membranes.