Crystal structure of human frataxin.
Friedreich's ataxia, an autosomal recessive neurodegenerative disorder characterized by progressive gait and limb ataxia, cardiomyopathy, and diabetes mellitus, is caused by decreased frataxin production or function. The structure of human frataxin, which we have determined at 1.8-A resolution, reveals a novel protein fold. A five-stranded, antiparallel beta sheet provides a flat platform, which supports a pair of parallel alpha helices, to form a compact alphabeta sandwich. A cluster of 12 acidic residues from the first helix and the first strand of the large sheet form a contiguous anionic surface on the protein. The overall protein structure and the anionic patch are conserved in eukaryotes, including animals, plants, and yeast, and in prokaryotes. Additional conserved residues create an extended 1008-A(2) patch on a distinct surface of the protein. Side chains of disease-associated mutations either contribute to the anionic patch, help create the second conserved surface, or point toward frataxin's hydrophobic core. These structural findings predict potential modes of protein-protein and protein-iron binding.
Dhe-Paganon
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Joslin Diabetes Center and Department of Medicine, Harvard Medical School, Boston, Massachusetts 02215, USA.
Shigeta
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Chi
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Ristow
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Shoelson
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D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D018360:Crystallography, X-Ray; D005621:Friedreich Ataxia / Q000235:genetics; D006801:Humans; D007501:Iron / Q000378:metabolism; D033862:Iron-Binding Proteins; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000737:chemistry* / Q000235:genetics; D011485:Protein Binding; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017386:Sequence Homology, Amino Acid; D000096923:Frataxin
D007501:Iron; D033862:Iron-Binding Proteins; D017853:Phosphotransferases (Alcohol Group Acceptor); D000096923:Frataxin