Reconstituted P2/myelin-lipid multilayers

Area of Science:

• Biochemistry
• Structural Biology
• Neuroscience

Background:

• Myelin basic protein (MBP) is a major component of the myelin sheath.
• The P2 protein is another significant myelin protein involved in nervous system structure.

Purpose of the Study:

• To investigate the structural complex formed between bovine P2 protein and myelin lipid vesicles.
• To determine the location and structural impact of P2 protein within lipid bilayers.

Main Methods:

• Biochemical analysis
• Freeze-fracture electron microscopy (FF EM)
• Thin-section electron microscopy (EM)
• X-ray diffraction

Main Results:

• P2 protein addition to lipid vesicles induced aggregation, fusion, and multilayer formation.
• X-ray diffraction showed a constant repeating distance of 86.0 ± 0.7 Å in multilayers with 4-15 wt% P2.
• Electron density profiles indicated P2 protein is primarily located in the interbilayer spaces, with some insertion into lipid headgroups.

Conclusions:

• Bovine P2 protein is a peripheral membrane protein that binds to myelin lipid bilayers.
• The P2 protein occupies the interbilayer space, widening it compared to MBP, suggesting a globular structure.
• Variations in P2 protein proportions across species may correlate with observed myelin structure differences.