A novel SOD1-dependent mechanism for the iron-induced production of toxic SOD1 and oxidative stress that initiates ALS

Free iron is highly toxic and the blood-derived iron initiates early motor-neuron degeneration upon breakdown of blood-spinal cord barrier. Iron is currently known to trigger oxidative stress by Fenton chemistry but no report implies that iron manifests its toxicity through CuZn-superoxide dismutase (SOD1), the central antioxidant enzyme in all human tissues that carries >180 ALS-causing mutations. Here, by NMR we show that Zn2+ play an irreplaceable role in the maturation of the nascent hSOD1, and further decipher for the first time that out of 11 other cations only Fe2+ has the Zn2+-like capacity to induce folding to form the Fe2+-bound hSOD1. This acts to reduce or even block the maturation of wild-type and ALS-causing mutant hSOD1, consequently trapping SOD1 in toxic forms and provoking oxidative stress. Our study establishes a novel SOD1-dependent mechanism for iron to manifest cellular toxicity that contributes to pathogenesis of neurodegenerative diseases, aging and even more.\n\nOne Sentence SummaryOur study establishes a novel SOD1-dependent mechanism for iron to manifest toxicity contributing to neurodegenerative diseases, aging and even more.