TY - JOUR
T1 - Mitochondrial iron detoxification is a primary function of frataxin that limits oxidative damage and preserves cell longevity
AU - Gakh, Oleksandr
AU - Park, Sungjo
AU - Liu, Gang
AU - Macomber, Lee
AU - Imlay, James A.
AU - Ferreira, Gloria C.
AU - Isaya, Grazia
N1 - Funding Information:
This work was supported by grants AG15709 (to G.I.) and GM49640 (to J.A.I.) from the National Institutes of Health and RSG-96-05106-TBE (to G.C.F.) from the American Cancer Society. Funding to pay the Open Access publication charges for this article was provided by a grant from the Friedreich Ataxia Research Alliance (FARA) (to G.I.).
PY - 2006/2/1
Y1 - 2006/2/1
N2 - Friedreich ataxia is a severe autosomal-recessive disease characterized by neurodegeneration, cardiomyopathy and diabetes, resulting from reduced synthesis of the mitochondrial protein frataxin. Although frataxin is ubiquitously expressed, frataxin deficiency leads to a selective loss of dorsal root ganglia neurons, cardiomyocytes and pancreatic beta cells. How frataxin normally promotes survival of these particular cells is the subject of intense debate. The predominant view is that frataxin sustains mitochondrial energy production and other cellular functions by providing iron for heme synthesis and iron-sulfur cluster (ISC) assembly and repair. We have proposed that frataxin not only promotes the biogenesis of iron-containing enzymes, but also detoxifies surplus iron thereby affording a critical anti-oxidant mechanism. These two functions have been difficult to tease apart, however, and the physiologic role of iron detoxification by frataxin has not yet been demonstrated in vivo. Here, we describe mutations that specifically impair the ferroxidation or mineralization activity of yeast frataxin, which are necessary for iron detoxification but do not affect the iron chaperone function of the protein. These mutations increase the sensitivity of yeast cells to oxidative stress, shortening chronological life span and precluding survival in the absence of the anti-oxidant enzyme superoxide dismutase. Thus, the role of frataxin is not limited to promoting ISC assembly or heme synthesis. Iron detoxification is another function of frataxin relevant to anti-oxidant defense and cell longevity that could play a critical role in the metabolically demanding environment of non-dividing neuronal, cardiac and pancreatic beta cells.
AB - Friedreich ataxia is a severe autosomal-recessive disease characterized by neurodegeneration, cardiomyopathy and diabetes, resulting from reduced synthesis of the mitochondrial protein frataxin. Although frataxin is ubiquitously expressed, frataxin deficiency leads to a selective loss of dorsal root ganglia neurons, cardiomyocytes and pancreatic beta cells. How frataxin normally promotes survival of these particular cells is the subject of intense debate. The predominant view is that frataxin sustains mitochondrial energy production and other cellular functions by providing iron for heme synthesis and iron-sulfur cluster (ISC) assembly and repair. We have proposed that frataxin not only promotes the biogenesis of iron-containing enzymes, but also detoxifies surplus iron thereby affording a critical anti-oxidant mechanism. These two functions have been difficult to tease apart, however, and the physiologic role of iron detoxification by frataxin has not yet been demonstrated in vivo. Here, we describe mutations that specifically impair the ferroxidation or mineralization activity of yeast frataxin, which are necessary for iron detoxification but do not affect the iron chaperone function of the protein. These mutations increase the sensitivity of yeast cells to oxidative stress, shortening chronological life span and precluding survival in the absence of the anti-oxidant enzyme superoxide dismutase. Thus, the role of frataxin is not limited to promoting ISC assembly or heme synthesis. Iron detoxification is another function of frataxin relevant to anti-oxidant defense and cell longevity that could play a critical role in the metabolically demanding environment of non-dividing neuronal, cardiac and pancreatic beta cells.
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U2 - 10.1093/hmg/ddi461
DO - 10.1093/hmg/ddi461
M3 - Article
C2 - 16371422
AN - SCOPUS:31544445770
SN - 0964-6906
VL - 15
SP - 467
EP - 479
JO - Human molecular genetics
JF - Human molecular genetics
IS - 3
ER -