Transient Interactions of α-Synuclein N- and C-Termini

Area of Science:

• Neuroscience
• Biochemistry
• Structural Biology

Background:

• Alpha-synuclein (αSyn) is a neuronal protein central to synaptic vesicle trafficking.
• αSyn aggregation forms Lewy bodies, the pathological hallmark of Parkinson's disease.
• Interactions between αSyn's N- and C-termini influence its structure, membrane binding, and aggregation.

Purpose of the Study:

• To investigate the transient contacts within αSyn in various conformational states using photoinduced cross-linking of unmodified proteins (PICUP).
• To elucidate the role of N- and C-terminal interactions in αSyn's physiological and pathological behavior.
• To map αSyn's interactions during self-assembly and membrane association.

Main Methods:

• Photoinduced cross-linking of unmodified proteins (PICUP) was employed to capture transient protein contacts.
• Tyrosine-to-phenylalanine mutations were used to selectively block cross-linking sites.
• PICUP was applied to αSyn in solution, bound to membranes, and in fibrillar states.

Main Results:

• Intramolecular N- and C-terminal contacts were identified in αSyn monomers in solution.
• Intermolecular C-terminal contacts were observed in αSyn oligomers.
• Membrane binding inhibited internal cross-linking but preserved C-terminal interactions.
• Cross-linking in αSyn fibrils was reduced, mainly involving adjacent C-termini.

Conclusions:

• PICUP effectively reports on transient contacts during αSyn self-assembly and membrane interactions.
• The study provides a streamlined protocol for investigating protein-protein interactions in various systems.
• Understanding αSyn's conformational dynamics and interactions is key to deciphering Parkinson's disease mechanisms.