Author:
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Parent, Aubérie; Elduque Busquets, Xavier; Cornu, David; Belot, Laura; Le Caer, Jean-Pierre; Grandas Sagarra, Anna; Toledano, Michel B.; D'Autréaux, Benoit
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Abstract:
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Friedreich's ataxia is a severe neurodegenerative disease caused by the decreased expression of frataxin, a mitochondrial protein that stimulates iron sulfur (Fe-S) cluster biogenesis. In mammals, the primary steps of Fe-S cluster assembly are performed by the NFS1 ISD11 ISCU complex via the formation of a persulfide intermediate on NFS1. Here we show that frataxin modulates the reactivity of NFS1 persulfide with thiols. We use maleimide-peptide com- pounds along with mass spectrometry to probe cysteine-persulfide in NFS1 and ISCU. Our data reveal that in the presence of ISCU, frataxin enhances the rate of two similar reactions on NFS1 persulfide: sulfur transfer to ISCU leading to the accumulation of a persulfide on the cysteine C104 of ISCU, and sulfur transfer to small thiols such as DTT, L-cysteine and GSH leading to persulfuration of these thiols and ultimately sulfide release. These data raise important questions on the physiological mechanism of Fe-S cluster assembly and point to a unique function of frataxin as an enhancer of sulfur transfer within the NFS1 ISD11 ISCU complex. |