Physical evidence that yeast frataxin is an iron storage protein

Oleksandr Gakh, Jiri Adamec, A. Marquis Gacy, Ray D. Twesten, Whyte G. Owen, Grazia Isaya

Research output: Contribution to journalArticle

104 Citations (Scopus)

Abstract

Frataxin is a conserved mitochondrial protein required for iron homeostasis. We showed previously that in the presence of ferrous iron recombinant yeast frataxin (mYfh1p) assembles into a regular multimer of ∼1.1 MDa storing ∼3000 iron atoms. Here, we further demonstrate that mYfh1p and iron form a stable hydrophilic complex that can be detected by either protein or iron staining on nondenaturing polyacrylamide gels, and by either interference or absorbance measurements at sedimentation equilibrium. The molecular mass of this complex has been refined to 840 kDa corresponding to 48 protein subunits and 2400 iron atoms. Solution density measurements have determined a partial specific volume of 0.58 cm3/g, consistent with the amino acid composition of mYfh1p and the presence of 50 Fe-O equivalents per subunit. By dynamic light scattering, we show that the complex has a radius of ∼11 nm and assembles within 2 min at 30 °C when ferrous iron, not ferric iron or other divalent cations, is added to mYfh1p monomer at pH between 6 and 8. Iron-rich granules with diameter of 2-4 nm are detected in the complex by scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy. These findings support the hypothesis that frataxin is an iron storage protein, which could explain the mitochondrial iron accumulation and oxidative damage associated with frataxin defects in yeast, mouse, and humans.

Original languageEnglish (US)
Pages (from-to)6798-6804
Number of pages7
JournalBiochemistry
Volume41
Issue number21
DOIs
StatePublished - May 28 2002

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Yeast
Iron
Yeasts
Proteins
frataxin
X-Ray Emission Spectrometry
Atoms
Scanning Transmission Electron Microscopy
Mitochondrial Proteins
Divalent Cations
Protein Subunits
Molecular mass
Dynamic light scattering
Sedimentation
Density (specific gravity)
Homeostasis
Monomers
Staining and Labeling
Transmission electron microscopy
Amino Acids

ASJC Scopus subject areas

  • Biochemistry

Cite this

Gakh, O., Adamec, J., Gacy, A. M., Twesten, R. D., Owen, W. G., & Isaya, G. (2002). Physical evidence that yeast frataxin is an iron storage protein. Biochemistry, 41(21), 6798-6804. https://doi.org/10.1021/bi025566+

Physical evidence that yeast frataxin is an iron storage protein. / Gakh, Oleksandr; Adamec, Jiri; Gacy, A. Marquis; Twesten, Ray D.; Owen, Whyte G.; Isaya, Grazia.

In: Biochemistry, Vol. 41, No. 21, 28.05.2002, p. 6798-6804.

Research output: Contribution to journalArticle

Gakh, O, Adamec, J, Gacy, AM, Twesten, RD, Owen, WG & Isaya, G 2002, 'Physical evidence that yeast frataxin is an iron storage protein', Biochemistry, vol. 41, no. 21, pp. 6798-6804. https://doi.org/10.1021/bi025566+
Gakh O, Adamec J, Gacy AM, Twesten RD, Owen WG, Isaya G. Physical evidence that yeast frataxin is an iron storage protein. Biochemistry. 2002 May 28;41(21):6798-6804. https://doi.org/10.1021/bi025566+
Gakh, Oleksandr ; Adamec, Jiri ; Gacy, A. Marquis ; Twesten, Ray D. ; Owen, Whyte G. ; Isaya, Grazia. / Physical evidence that yeast frataxin is an iron storage protein. In: Biochemistry. 2002 ; Vol. 41, No. 21. pp. 6798-6804.
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