A non-essential function for yeast frataxin in iron-sulfur cluster assembly

Duby, Geoffrey;Foury, Françoise;Ramazzotti, Anna;Herrmann, Johannes;Lutz, Thomas
(2002) Human Molecular Genetics — Vol. 11, n° 21, p. 2635-2643 (2002)

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  • Duby, GeoffreyUCLouvain
    Author
  • Foury, FrançoiseUCLouvain
    Author
  • Ramazzotti, Anna
    Author
  • Herrmann, Johannes
    Author
  • Lutz, Thomas
    Author
Abstract
Friedreich's ataxia is caused by a deficit in frataxin, a small mitochondrial protein of unknown function that has been conserved during evolution. Previous studies have pointed out a role for frataxin in mitochondrial iron-sulfur (Fe-S) metabolism. Here, we have analyzed the incorporation of Fe-S clusters into yeast ferredoxin imported into isolated energized mitochondria from cells grown in the presence of glycerol, an obligatory respiratory carbon source. Similar amounts of apo-ferredoxin precursor were imported into mitochondria and processed in wild-type and yfh1-deleted (delta YF111) strains. However, the incorporation of Fe-S clusters into apo-ferredoxin was significantly reduced in delta YFH1 mitochondria. The newly assembled ferredoxin was stable, excluding the possibility that the decreased incorporation was a result of increased oxidative damage. When delta YFH1 cells were grown in raffinose medium, the formation of holo-ferredoxin was low, as a consequence of the decrease in ferredoxin precursor import into mitochondria. However, the decrease in the conversion rate of apo- into holo-ferredoxin was in the same range as for glycerol-grown cells, indicating that the extent of the defect in Fe-S protein assembly is similar under different physiological conditions. These data show that frataxin is not essential for Fe-S protein assembly, but improves the efficiency of the process. The large variations observed in the activity of Fe-S cluster proteins under different physiological conditions result from secondary defects in the physiology of delta YFH1 cells.
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Duby, G., Foury, F., Ramazzotti, A., Herrmann, J., & Lutz, T. (2002). A non-essential function for yeast frataxin in iron-sulfur cluster assembly. Human Molecular Genetics, 11(21), 2635-2643. https://doi.org/10.1093/hmg/11.21.2635 (Original work published 2002)