Amyloid Oligomers: Expediting Crystal Growth and Revisiting the Corkscrew Structures

Crystallizing soluble amyloid oligomers (AOs) presents
a major
challenge in studying disease-related mutations associated with amyloid
diseases. The G37R mutation in superoxide dismutase 1 (SOD1) is linked
to early onset amyotrophic lateral sclerosis (ALS), yet its toxic
mechanism remains unclear. The transient nature and low solubility
of AOs often complicate the production of high-quality crystals required
for X-ray crystallography (XRC) analysis. To address these challenges,
we employ native ion mobility spectrometry-mass spectrometry (IMS-MS)
to screen SOD1 peptides and examine correlations between structural
features that reflect AO stability, their sequence length, and specific
mutations. In particular, previous studies showed that the P28K mutation
in SOD1(28–38) enhances solubility, thus allowing the capture
of AO corkscrew structures for both SOD1(28–38)P28K and SOD1(28–38)P28K, G37R. Building on these
findings, we expanded our screening to include SOD1 peptides with
longer sequences, identifying structural features in IMS-MS spectra
that correlate with improved crystallization potential. This approach
enabled us to distinguish the stabilizing effects of G37R from those
of P28K, culminating in the successful determination of the first
crystal structure of the SOD1 corkscrew containing the native proline.