Early stage β-amyloid-membrane interactions modulate lipid dynamics and influence structural interfaces and...

Area of Science:

• Neuroscience
• Biochemistry
• Structural Biology

Background:

• Molecular interactions between beta-amyloid (Aβ) peptides and neuronal membranes are crucial for Alzheimer's disease pathology.
• Neuronal plasma membranes influence Aβ aggregation and the structural diversity of Aβ aggregates.
• The precise nature of Aβ-lipid interactions at the early stages of aggregation remains largely unknown.

Purpose of the Study:

• To investigate the site-specific interactions between Aβ peptides and lipids in synaptic plasma membranes.
• To elucidate the role of these interactions in the membrane-associated nucleation stage of Aβ fibrillation.
• To understand how early Aβ-lipid interactions influence the structure of Aβ aggregates.

Main Methods:

• Solid-state Nuclear Magnetic Resonance (NMR) spectroscopy was employed to study Aβ peptides and lipids within synaptic plasma membranes.
• Site-specific interactions and their effects on lipid dynamics were analyzed.

Main Results:

• Specific segments of the Aβ peptide's hydrophobic sequence mediate initial membrane binding and interstrand assembly.
• Early-stage Aβ-lipid interactions alter membrane dynamics, increasing lipid headgroup motion and decreasing lateral diffusion.
• These interactions lead to membrane-associated Aβ fibrils with a unique C-terminal quaternary interface structure compared to those formed in solution.

Conclusions:

• A schematic mechanism for Aβ-lipid interactions driving membrane-associated nucleation is proposed.
• These findings provide molecular insights into the early events of Aβ fibrillation in biological membrane environments.
• Understanding these interactions is key to deciphering the molecular mechanisms underlying Alzheimer's disease pathogenesis.