Fragmentation of phospholipid bilayers by myelin basic protein

Area of Science:

• Biochemistry
• Biophysics
• Neuroscience

Background:

• Myelin basic protein (MBP) is a key component of the myelin sheath.
• Lipid bilayers form the structural basis of cell membranes.
• Demyelinating diseases involve damage to the myelin sheath.

Purpose of the Study:

• To investigate the effect of human myelin basic protein (MBP) on phosphatidylcholine bilayers.
• To elucidate the mechanism of MBP-induced membrane disruption.
• To explore the potential role of MBP in demyelinating diseases.

Main Methods:

• Multilamellar phosphatidylcholine bilayers were used as a model system.
• 31P nuclear magnetic resonance (NMR) spectroscopy monitored bilayer fragmentation.
• Lipid composition, including phosphatidylserine and calcium ions, was varied.

Main Results:

• MBP disrupted phosphatidylcholine bilayers into lipoprotein particles, similar to melittin.
• Bilayer fragmentation was temperature-dependent.
• Negatively charged phosphatidylserine inhibited fragmentation, an effect lost upon calcium ion binding.
• MBP did not fragment bilayers mimicking myelin lipid composition.

Conclusions:

• MBP can induce bilayer fragmentation in vitro.
• Phosphatidylserine stabilizes membranes against MBP-induced disruption.
• Calcium ions neutralize the stabilizing effect of phosphatidylserine.
• MBP-induced membrane fragmentation may contribute to the pathogenesis of demyelinating diseases.