Characterization of Molecular Tweezer Binding on α-Synuclein with Native Top-Down Mass Spectrometry and Ion Mobility-Mass Spectrometry Reveals a Mechanism for Aggregation Inhibition

Parkinson's disease, a neurodegenerative disease that affects 15 million people worldwide, is characterized by deposition of alpha-synuclein into Lewy Bodies in brain neurons. Although this disease is prevalent worldwide, a therapy or cure has yet to be found. Several small compounds have been reported to disrupt fibril formation. Among these compounds is a molecular tweezer known as CLR01 that targets lysine and arginine residues. This study aims to characterize how CLR01 interacts with various proteoforms of alpha-synuclein and how the structure of alpha-synuclein is subsequently altered. Native mass spectrometry (nMS) measurements of alpha-synuclein/CLR01 complexes reveal that multiple CLR01 molecules can bind to alpha-synuclein proteoforms such as alpha-synuclein phosphorylated at Ser-129 and alpha-synuclein bound with copper and manganese ions. The binding of one CLR01 molecule shifts the ability for alpha-synuclein to bind other ligands. Electron capture dissociation (ECD) with Fourier transform-ion cyclotron resonance (FT-ICR) top-down (TD) mass spectrometry of alpha-synuclein/CLR01 complexes pinpoints the locations of the modifications on each proteoform and reveals that CLR01 binds to the N-terminal region of alpha-synuclein. CLR01 binding compacts the gas-phase structure of alpha-synuclein, as shown by ion mobility-mass spectrometry (IM-MS). These data suggest that when multiple CLR01 molecules bind, the N-terminus of alpha-synuclein shifts toward a more compact state. This compaction suggests a mechanism for CLR01 halting the formation of oligomers and fibrils involved in many neurodegenerative diseases.

Automated summary

This study investigates the interaction between CLR01 and different proteoforms of alpha-synuclein and how it affects the structure of alpha-synuclein. The results show that CLR01 can bind to various proteoforms of alpha-synuclein and alter its ability to bind other ligands. Additionally, CLR01 compacts the structure of alpha-synuclein, suggesting a mechanism for halting the formation of oligomers and fibrils associated with neurodegenerative diseases.