Cu(II) and dopamine bind to [alpha]-synuclein and cause large conformational changes

• Published in: The FEBS journal Vol. 281; no. 12; p. 2738
• Main Authors: Tavassoly, Omid, Nokhrin, Sergiy, Dmitriev, Oleg Y, Lee, Jeremy S
• Format: Journal Article
• Language: English
• Published: Oxford Blackwell Publishing Ltd 01-06-2014
• Subjects: Dopamine; Neurons; Parkinson's disease; Proteins
• ISSN: 1742-464X; 1742-4658
• DOI: 10.1111/febs.12817

[alpha]-Synuclein (AS) is an intrinsically disordered protein that can misfold and aggregate to form Lewy bodies in dopaminergic neurons, a classic hallmark of Parkinson's disease. The binding of Cu(II) and dopamine to AS was evaluated by nanopore analysis with [alpha]-hemolysin. In the absence of Cu(II), wild-type AS (1 µm) readily translocated through the pore with a blockade current of - 85 pA, but mostly bumping events were observed in the presence of 25 µm Cu(II). A binding site in the N-terminus was confirmed, because Cu(II) had no effect on the event profile of a peptide consisting of the C-terminal 96-140 residues. In the presence of dopamine (25 µm), the translocation events at - 85 pA shifted to - 80 pA, which also represents translocation events, because the event time decreases with increasing voltage. Events at - 80 pA were also observed for the mutant A30P AS in the presence of dopamine. Event profiles for an N-terminal 1-60-residue peptide and a C-terminal 96-140-residue peptide were both altered in the presence of 25 µm dopamine. In contrast, dopamine had little effect on the CD spectrum of AS, and a single binding site with a Ka of 3.5 × 103 m-1 was estimated by isothermal titration calorimetry. Thus, dopamine can interact with both the N-terminus and the C-terminus. Two-dimensional NMR spectroscopy of AS in the presence of dopamine showed that there were significant changes in the spectra in all regions of the protein. According to these findings, a model is presented in which dopamine induces folding between the N-terminus and C-terminus of AS. Partially folding conformations such as this may represent important intermediates in the misfolding of AS that leads to fibrillization. [PUBLICATION ABSTRACT]