The expression of human mitochondrial ferritin rescues respiratory function in frataxin-deficient yeast.
Mitochondrial ferritin (MtF) is structurally and functionally similar to the cytosolic ferritins, molecules designed to store and detoxify cellular iron. MtF expression in human and mouse is restricted to the testis and few tissues, and it is abundant in the erythroblasts of patients with sideroblastic anemia, where it is thought to protect the mitochondria from the damage caused by iron loading. Mitochondria iron overload occurs also in cells deficient in frataxin, a mitochondrial protein involved in iron handling and implicated in Friedreich ataxia. We expressed human MtF in frataxin-deficient yeast cells, a well-characterized model of mitochondrial iron overload and oxidative damage. The human MtF precursor was efficiently imported by yeast mitochondria and processed to functional ferritin that actively sequestered iron in the organelle. MtF expression rescued the respiratory deficiency caused by the loss of frataxin protecting the activity of iron-sulfur enzymes and enabling frataxin-deficient cells to grow on non-fermentable carbon sources. Furthermore, MtF expression prevented the development of mitochondrial iron overload, preserved mitochondrial DNA integrity and increased cell resistance to H2O2. The data show that MtF can substitute for most frataxin functions in yeast, suggesting that frataxin is directly involved in mitochondrial iron-binding and detoxification.
Campanella
Alessandro
A
Department of Biological and Technological Research, IRCCS H San Raffaele, Via Olgettina 58, Milano, 20132 Italy.
Isaya
Grazia
G
O'Neill
Heather A
HA
Santambrogio
Paolo
P
Cozzi
Anna
A
Arosio
Paolo
P
Levi
Sonia
S
D004272:DNA, Mitochondrial / Q000378:metabolism; D005293:Ferritins / Q000235:genetics / Q000378:metabolism*; D005621:Friedreich Ataxia / Q000235:genetics / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007501:Iron / Q000378:metabolism*; D019190:Iron Overload; D033862:Iron-Binding Proteins / Q000235:genetics / Q000502:physiology*; D007506:Iron-Sulfur Proteins / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism*; D016877:Oxidants / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D000096923:Frataxin
D004272:DNA, Mitochondrial; D005293:Ferritins; D006861:Hydrogen Peroxide; D007501:Iron; D033862:Iron-Binding Proteins; D007506:Iron-Sulfur Proteins; D016877:Oxidants; D000096923:Frataxin