A30P and A30G Mutations in α-Synuclein Promote Metastable Long-Lived Aggregates with Distinct Structural Responses to...

Area of Science:

• Neuroscience
• Biochemistry
• Structural Biology

Background:

• Synucleinopathies involve misfolded alpha-synuclein (α-synuclein) accumulation in brain cells.
• The precise role of α-synuclein mutations in disease exacerbation is not fully understood.

Purpose of the Study:

• To investigate the aggregation kinetics and pathway of α-synuclein mutants (A30P, A30G) compared to wild-type (WT).
• To characterize the structural properties of aggregation intermediates and the impact of amyloid modulators.

Main Methods:

• In vitro aggregation kinetics assays.
• Circular dichroism (CD) spectroscopy and atomic force microscopy (AFM).
• AFM-Raman spectroscopy, proteinase-K digestion, and treatment with EGCG.

Main Results:

• A30P and A30G mutants exhibited slower aggregation kinetics than WT, forming kinetically metastable aggregates.
• Structural analysis revealed variant-specific differences in aggregate stability (A30P < A30G < WT).
• The amyloid modulator EGCG converted aggregates to different structures and influenced monomer aggregation.

Conclusions:

• α-synuclein A30 mutations may increase toxicity by generating long-lived prefibrillar species, not just alternative conformations.
• These metastable conformers exhibit differential sensitivity to amyloid modulators.
• Findings offer insights into synucleinopathy mechanisms and therapeutic strategies targeting α-synuclein aggregation.