Determining the Location of the α-Synuclein Dimer Interface Using Native Top-Down Fragmentation and Isotope...

Area of Science:

• Biochemistry
• Neuroscience
• Structural Biology

Background:

• Alpha-synuclein (αSyn) is intrinsically disordered and linked to Parkinson's disease (PD) pathology.
• The endogenous structure and physiological functions of αSyn remain incompletely understood.
• Lewy bodies are primarily composed of αSyn.

Purpose of the Study:

• To elucidate the structural properties of a stable, naturally occurring αSyn dimer.
• To investigate the structural basis of αSyn aggregation in Parkinson's disease.
• To develop and apply advanced mass spectrometry techniques for studying protein structure.

Main Methods:

• Ion mobility-mass spectrometry
• Native top-down electron capture dissociation fragmentation
• Isotopically depleted protein generation for enhanced signal-to-noise ratio

Main Results:

• A stable dimer of αSyn was identified in both wild-type and the PD-associated A53E variant.
• Fragments unique to the dimer were assigned, indicating a C-terminal to C-terminal interaction between monomers.
• The novel workflow enabled confident identification of low-abundance fragment ions.

Conclusions:

• The study reveals a specific C-terminal interaction in a stable αSyn dimer.
• The applied methodology enhances the investigation of endogenous multimeric protein species.
• This work provides structural insights into αSyn relevant to Parkinson's disease.