Cholesterol suppresses membrane leakage by decreasing water penetrability

Area of Science:

• Biophysics
• Cell Biology
• Biochemistry

Background:

• Membrane fusion is vital for viral infection, neurotransmission, and fertilization.
• Fusion involves a hemifusion diaphragm, with content release potentially occurring via fusion pores or leaky fusion.
• Understanding hemifusion diaphragm evolution is crucial for deciphering content leakage mechanisms.

Purpose of the Study:

• To investigate the structural evolution of the hemifusion diaphragm using molecular dynamics simulations.
• To determine the role of lipid composition, specifically cholesterol, in regulating hemifusion diaphragm stability and pore formation.
• To elucidate the mechanisms underlying content leakage during membrane fusion.

Main Methods:

• All-atom molecular dynamics simulations were employed to model hemifusion diaphragm formation and stability.
• Various lipid compositions were simulated to assess their impact on membrane structure.
• Biochemical leakage experiments were conducted to validate simulation findings.

Main Results:

• Cholesterol was found to decrease water penetrability within the hemifusion diaphragm.
• This reduced water penetration effectively inhibited the formation of leakage pores.
• Simulation results were corroborated by biochemical experiments, supporting cholesterol's inhibitory role.

Conclusions:

• Cholesterol plays a significant role in stabilizing the hemifusion diaphragm by limiting water ingress.
• This stabilization mechanism inhibits leaky fusion, ensuring controlled content release during membrane fusion.
• The study provides insights into the structural basis of content leakage, with implications for viral entry and cellular transport.