TY - JOUR
T1 - Human frataxin maintains mitochondrial iron homeostasis in Saccharomyces cerevisiae
AU - Cavadini, Patrizia
AU - Gellera, Cinzia
AU - Patel, Pragna I.
AU - Isaya, Grazia
PY - 2000/10/12
Y1 - 2000/10/12
N2 - Frataxin is a nuclear-encoded mitochondrial protein widely conserved among eukaryotes. Human frataxin (fxn) is severely reduced in Friedreich ataxia (FRDA), a frequent autosomal recessive neuro- and cardio-degenerative disease. Whereas the function of fxn is unknown, the yeast frataxin homolog (Yfh1p) has been shown to be involved in mitochondrial iron homeostasis and protection from free radical toxicity. Evidence of iron accumulation and oxidative damage in cardiac tissue from FRDA patients suggests that fxn may have a similar function, but whether yeast and human frataxin actually have interchangeable roles in mitochondrial iron homeostasis is unknown. We show that a wild-type FRDA cDNA can complement Yfh1p-deficient yeast (yfh1Δ) by preventing the mitochondrial iron accumulation and oxidative damage associated with loss of Yfh1p. We analyze the functional effects of two FRDA point mutations, G130V and W173G, associated with a mild and a severe clinical presentation, respectively. The G130V mutation affects protein stability and results in low levels of mature (m) fxn, which are nevertheless sufficient to rescue yfh1Δ yeast. The W173G mutation affects protein processing and stability and results in severe m-fxn deficiency. Expression of the FRDA (W173G) cDNA in yfh1Δ yeast leads to increased levels of mitochondrial iron which are not as elevated as in Yfh1p-deficient cells but are above the threshold for oxidative damage of mitochondrial DNA and iron-sulfur centers, causing a typical yfh1Δ phenotype. These results demonstrate that fxn functions like Yfh1p, providing experimental support to the hypothesis that FRDA is a disorder of mitochondrial iron homeostasis.
AB - Frataxin is a nuclear-encoded mitochondrial protein widely conserved among eukaryotes. Human frataxin (fxn) is severely reduced in Friedreich ataxia (FRDA), a frequent autosomal recessive neuro- and cardio-degenerative disease. Whereas the function of fxn is unknown, the yeast frataxin homolog (Yfh1p) has been shown to be involved in mitochondrial iron homeostasis and protection from free radical toxicity. Evidence of iron accumulation and oxidative damage in cardiac tissue from FRDA patients suggests that fxn may have a similar function, but whether yeast and human frataxin actually have interchangeable roles in mitochondrial iron homeostasis is unknown. We show that a wild-type FRDA cDNA can complement Yfh1p-deficient yeast (yfh1Δ) by preventing the mitochondrial iron accumulation and oxidative damage associated with loss of Yfh1p. We analyze the functional effects of two FRDA point mutations, G130V and W173G, associated with a mild and a severe clinical presentation, respectively. The G130V mutation affects protein stability and results in low levels of mature (m) fxn, which are nevertheless sufficient to rescue yfh1Δ yeast. The W173G mutation affects protein processing and stability and results in severe m-fxn deficiency. Expression of the FRDA (W173G) cDNA in yfh1Δ yeast leads to increased levels of mitochondrial iron which are not as elevated as in Yfh1p-deficient cells but are above the threshold for oxidative damage of mitochondrial DNA and iron-sulfur centers, causing a typical yfh1Δ phenotype. These results demonstrate that fxn functions like Yfh1p, providing experimental support to the hypothesis that FRDA is a disorder of mitochondrial iron homeostasis.
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U2 - 10.1093/hmg/9.17.2523
DO - 10.1093/hmg/9.17.2523
M3 - Article
C2 - 11030757
AN - SCOPUS:0034641851
SN - 0964-6906
VL - 9
SP - 2523
EP - 2530
JO - Human molecular genetics
JF - Human molecular genetics
IS - 17
ER -