Exploring iron-binding to human frataxin and to selected Friedreich ataxia mutants by means of NMR and EPR spectroscopies

Publication date: Available online 22 July 2019Source: Biochimica et Biophysica Acta (BBA) - Proteins and ProteomicsAuthor(s): Massimo Bellanda, Lorenzo Maso, Davide Doni, Marco Bortolus, Edith De Rosa, Federica Lunardi, Arianna Alfonsi, Martín Ezequiel Noguera, Maria Georgina Herrera, Javier Santos, Donatella Carbonera, Paola CostantiniAbstractThe neurodegenerative disease Friedreich ataxia results from a deficiency of frataxin, a mitochondrial protein. Most patients have a GAA expansion in the first intron of both alleles of frataxin gene, whereas a minority of them are heterozygous for the expansion and contain a mutation in the other allele. Frataxin has been claimed to participate in iron homeostasis and biosynthesis of FeS clusters, however its role in both pathways is not unequivocally defined. In this work we combined different advanced spectroscopic analyses to explore the iron-binding properties of human frataxin, as isolated and at the FeS clusters assembly machinery. For the first time we used EPR spectroscopy to address this key issue providing clear evidence of the formation of a complex with a low symmetry coordination of the metal ion. By 2D NMR, we confirmed that iron can be bound in both oxidation states, a controversial issue, and, in addition, we were able to point out a transient interaction of frataxin with a N-terminal 6his-tagged variant of ISCU, the scaffold protein of the FeS clusters assembly machinery. To obtain insights on structure/function rela...
Source: Biochimica et Biophysica Acta (BBA) Proteins and Proteomics - Category: Biochemistry Source Type: research