NMR Characterization of α-Synuclein Interactions with GCase-Targeting Pharmacological Chaperone

Nuclear Magnetic Resonance (NMR) spectroscopy is a powerful technique for characterizing intrinsically disordered proteins (IDPs) and their interactions at atomic resolution with binding partners, such as small molecules and metal ions. This study focuses on human α-synuclein (α-syn), an IDP closely associated with neurodegenerative disorders, including Parkinson’s disease (PD). Mutations in the GBA1 gene, which encode the lysosomal enzyme glucocerebrosidase (GCase), are responsible for Gaucher disease and represent one of the most common genetic risk factors for PD. Reduced GCase activity promotes α-syn aggregation, thereby contributing to PD pathogenesis Following a “dual-target” approach, we investigated ambroxol, a mucolytic drug under clinical evaluation for GCase-related disorders that acts as a pharmacological chaperone (PC) for GCase and also interacts with the intrinsically disordered monomeric form of α-syn. To study the interplay between ambroxol and α-syn, we employed high-resolution NMR spectroscopy, utilizing both 13C- and 1H-detected experiments, focusing on backbone and side-chain changes upon interaction. Side chains generally play a key role in mediating and modulating molecular recognition. Monitoring chemical-shift changes in amino-acid side-chain nuclear spins brings us closer to the main interaction sites, providing additional insight.