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Ancestral roles of eukaryotic frataxin: mitochondrial frataxin function and heterologous expression of hydrogenosomal Trichomonas homologs in trypanosomes.

Long, Shaojun and Jirku, Milan and Mach, Jan and Ginger, Michael L. and Sutak, Robert and Richardson, Des and Tachezy, Jan and Lukes, Julius (2008) Ancestral roles of eukaryotic frataxin: mitochondrial frataxin function and heterologous expression of hydrogenosomal Trichomonas homologs in trypanosomes. Molecular Microbiology, 69 (1). pp. 94-109. ISSN 0950-382X

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Abstract

Frataxin is a small conserved mitochondrial protein; in humans, mutations affecting frataxin expression or function result in Friedreich's ataxia. Much of the current understanding of frataxin function comes from informative studies with yeast models, but considerable debates remain with regard to the primary functions of this ubiquitous protein. We exploit the tractable reverse genetics of Trypanosoma brucei in order to specifically consider the importance of frataxin in an early branching lineage. Using inducible RNAi, we show that frataxin is essential in T. brucei and that its loss results in reduced activity of the marker Fe-S cluster-containing enzyme aconitase in both the mitochondrion and cytosol. Activities of mitochondrial succinate dehydrogenase and fumarase also decreased, but the concentration of reactive oxygen species increased. Trypanosomes lacking frataxin also exhibited a low mitochondrial membrane potential and reduced oxygen consumption. Crucially, however, iron did not accumulate in frataxin-depleted mitochondria, and as T. brucei frataxin does not form large complexes, it suggests that it plays no role in iron storage. Interestingly, RNAi phenotypes were ameliorated by expression of frataxin homologues from hydrogenosomes of another divergent protist Trichomonas vaginalis. Collectively, the data suggest trypanosome frataxin functions primarily only in Fe-S cluster biogenesis and protection from reactive oxygen species.

Item Type: Article
Journal or Publication Title: Molecular Microbiology
Subjects: Q Science > QH Natural history > QH301 Biology
Departments: Faculty of Health and Medicine > Biomedical & Life Sciences
ID Code: 34888
Deposited By: Dr Michael Ginger
Deposited On: 14 Dec 2010 14:00
Refereed?: Yes
Published?: Published
Last Modified: 26 Jul 2012 17:43
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/34888

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