Structural mapping of oligomeric intermediates in an amyloid assembly pathway

Area of Science:

• Biochemistry
• Structural Biology
• Medical Biochemistry

Background:

• Amyloid assembly involves transient oligomers in early stages.
• Understanding these species is crucial for controlling amyloid-related diseases.
• Dialysis-related amyloidosis involves amyloid deposits in joints.

Purpose of the Study:

• To structurally characterize oligomers involved in amyloid assembly of human beta2-microglobulin (β2m) variant ΔN6.
• To elucidate the pathway of amyloid formation initiated by these oligomers.

Main Methods:

• Chemical kinetics
• Nuclear Magnetic Resonance (NMR) spectroscopy
• Biophysical methods

Main Results:

• Identified and characterized head-to-head non-toxic dimers and hexamers as key intermediates.
• Revealed a pathway initiated by these oligomers leading to amyloid fibrils.
• Demonstrated that precise subunit organization dictates amyloid assembly.

Conclusions:

• Amyloid assembly of ΔN6 β2m proceeds via structured, non-toxic oligomers.
• Specific oligomer organization is critical for amyloid formation.
• Dynamics in the C-terminal strand suggest initiation of cross-β structure.