Amyloid Oligomers: Expediting Crystal Growth and Revisiting the Corkscrew Structures

Area of Science:

• Biochemistry
• Structural Biology
• Neuroscience

Background:

• Crystallizing soluble amyloid oligomers (AOs) is crucial for understanding amyloid diseases.
• The G37R mutation in superoxide dismutase 1 (SOD1) is linked to early onset amyotrophic lateral sclerosis (ALS), but its toxic mechanism is unclear.
• Low solubility and transient nature of AOs hinder X-ray crystallography (XRC) analysis.

Purpose of the Study:

• To overcome challenges in crystallizing SOD1 amyloid oligomers (AOs).
• To identify structural features correlating with AO stability and crystallization potential using native ion mobility spectrometry-mass spectrometry (IMS-MS).
• To elucidate the role of G37R and P28K mutations in SOD1 AO structure and stability.

Main Methods:

• Screening of SOD1 peptides with varying sequences and mutations using native ion mobility spectrometry-mass spectrometry (IMS-MS).
• Analyzing correlations between structural features, AO stability, sequence length, and specific mutations.
• Utilizing previous findings on the P28K mutation's effect on SOD1 solubility and AO corkscrew structure.

Main Results:

• Identified structural features in IMS-MS spectra indicative of improved crystallization potential in SOD1 peptides.
• Successfully distinguished the stabilizing effects of the G37R mutation from the P28K mutation.
• Determined the first crystal structure of a SOD1 corkscrew oligomer containing the native proline.

Conclusions:

• Native IMS-MS is effective for screening SOD1 peptides and predicting crystallization potential.
• The G37R mutation has distinct stabilizing effects on SOD1 AOs compared to P28K.
• The determined crystal structure provides new insights into SOD1 AO formation and its implications for ALS.