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The Journal of Biological Chemistry

Year: 2008  |  Volume: 283  |  Issue: 18  |  Page No.: 12674 - 12679

Binding of Yeast Frataxin to the Scaffold for Fe-S Cluster Biogenesis, Isu

Tao Wang and Elizabeth A. Craig

Abstract

Friedreich ataxia is caused by reduced activity of frataxin, a conserved iron-binding protein of the mitochondrial matrix, thought to supply iron for formation of Fe-S clusters on the scaffold protein Isu. Frataxin binds Isu in an iron-dependent manner in vitro. However, the biological relevance of this interaction and whether in vivo the interaction between frataxin and Isu is mediated by adaptor proteins is a matter of debate. Here, we report that alterations of conserved, surface-exposed residues of yeast frataxin, which have deleterious effects on cell growth, impair Fe-S cluster biogenesis and interaction with Isu while altering neither iron binding nor oligomerization. Our results support the idea that the surface of the β-sheet, adjacent to the acidic, iron binding ridge, is important for interaction of Yfh1 with the Fe-S cluster scaffold and point to a critical role for frataxin in Fe-S cluster biogenesis.

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