Dimers of D76N-β₂-microglobulin display potent antiamyloid aggregation activity

Area of Science:

• Biochemistry
• Structural Biology
• Molecular Biophysics

Background:

• Dialysis-related amyloidosis is linked to wild-type beta-2-microglobulin (WT-β2m) self-association into amyloid fibrils.
• The familial D76N-β2m variant exhibits enhanced aggregation, causing amyloidosis independent of kidney function.
• Previous studies focused on native protein structures and aggregation potentials, leaving transient oligomers uncharacterized.

Purpose of the Study:

• To structurally characterize transient dimers of the D76N-β2m protein.
• To investigate the role of these dimers in the amyloid assembly pathway.
• To explore the potential of D76N-β2m dimers as inhibitors of amyloid formation.

Main Methods:

• Nuclear Magnetic Resonance (NMR) spectroscopy
• Photo-induced crosslinking techniques
• Structural characterization of transient protein dimers

Main Results:

• Transient D76N-β2m dimers were detected, trapped, and structurally characterized.
• These dimers possess distinct structures compared to other β2m dimers.
• The identified D76N-β2m dimers inhibit amyloid formation by blocking nucleation and elongation.

Conclusions:

• The structural properties of transient D76N-β2m dimers differ significantly from on-pathway dimers.
• D76N-β2m dimers act as potent inhibitors of amyloid assembly, even in substoichiometric amounts.
• Mapping protein-protein interaction interfaces is key to developing novel amyloid inhibition strategies.