Horvath I, Blockhuys S, Šulskis D, Holgersson S, Kumar R, Burmann BM, Wittung-Stafshede P
ACS Chem Neurosci 10 (11) 4659-4668 [2019-11-20; online 2019-10-24]
Alterations in copper ion homeostasis appear coupled to neurodegenerative disorders, but mechanisms are unknown. The cytoplasmic copper chaperone Atox1 was recently found to inhibit amyloid formation in vitro of α-synuclein, the amyloidogenic protein in Parkinson's disease. As α-synuclein may have copper-dependent functions, and free copper ions promote α-synuclein amyloid formation, it is important to characterize the Atox1 interaction with α-synuclein on a molecular level. Here we applied solution-state nuclear magnetic resonance spectroscopy, with isotopically labeled α-synuclein and Atox1, to define interaction regions in both proteins. The α-synuclein interaction interface includes the whole N-terminal part up to Gln24; in Atox1, residues around the copper-binding cysteines (positions 11-16) are mostly perturbed, but additional effects are also found for residues elsewhere in both proteins. Because α-synuclein is N-terminally acetylated in vivo, we established that Atox1 also inhibits amyloid formation of this variant in vitro, and proximity ligation in human cell lines demonstrated α-synuclein-Atox1 interactions in situ. Thus, this interaction may provide the direct link between copper homeostasis and amyloid formation in vivo.