Cross-Linking and Covalent Labeling Mass Spectrometry Reveal Proteoform-Driven Conformational Changes in Alpha...

Area of Science:

• Neuroscience
• Biochemistry
• Structural Biology

Background:

• Phosphorylation of alpha synuclein at serine 129 (pS129) is linked to neurodegenerative diseases.
• pS129 plays a role in neurotransmitter release and synaptic vesicle cycling.
• Alpha synuclein is an intrinsically disordered protein with various post-translational modifications.

Purpose of the Study:

• To investigate how post-translational modifications, specifically pS129, alter alpha synuclein's structural ensembles.
• To examine oxidized forms of alpha synuclein (M1, M5, M116, M127) in the brain.
• To map residue proximity and solvent accessibility in different alpha synuclein proteoforms.

Main Methods:

• Utilizing tandem mass spectrometry.
• Employing chemical cross-linking to map residue proximity.
• Using covalent labeling to identify solvent accessible residues and microenvironment hydrophobicity.

Main Results:

• Demonstrated that pS129 stabilizes a more compact alpha synuclein conformation.
• Identified solvent accessible residues and microenvironment characteristics.
• Mapped residue-residue proximities in different alpha synuclein proteoforms.

Conclusions:

• Phosphorylation at S129 significantly impacts alpha synuclein structure.
• The study provides a structural basis for understanding pS129's role in neurodegeneration.
• Tandem mass spectrometry combined with cross-linking and labeling is effective for studying protein structural ensembles.