• CD of proteins
• Fe-S cluster
• Frataxin
• Friedreich ataxia
• isc operon

Iron-sulfur clusters are essential prosthetic groups that are formed under the control of complex machineries highly conserved from bacteria to humans. In bacteria, the genes responsible for cluster biogenesis are mostly grouped in three distinct operons, among which is the Isc operon. This is found in most organisms and contains 7-10 genes. Each of the Isc gene products has a close orthologue in eukaryotes.
Abnormal Fe-S protein biogenesis and mitochondrial iron accumulation in hearth and neurones are for instance part of the typical phenotype of a genetic neurodegenerative disease, Friedreich’s Ataxia. This pathology is caused by the deficiency of a mitochondrial protein, frataxin, extremely conserved throughout species. Although the frataxin function is still unclear, it was proved that this protein is able to bind iron in vitro and in vivo so that it was suggested a role as iron storage or as iron chaperone in the Fe-S cluster biosynthesis. To determine frataxin structural features and differences between species, it is fundamental to completely characterise the system and its modification through evolution.
The final aim of this thesis has been to provide evidence to clarify frataxin’s role in the machinery of Fe-S cluster biosynthesis and to point out some frataxin’s structural properties.