Trypanosoma brucei, the agent of human sleeping sickness and ruminant nagana, is the most genetically tractable representative of the domain Excavata. It is evolutionarily very distant from humans, with a last common ancestor over 1 billion years ago. Frataxin, a highly conserved small protein involved in iron-sulfur cluster synthesis, is present in both organisms, and its deficiency is responsible for Friedreich's ataxia in humans. We have found that T. brucei growth-inhibition phenotype caused by down-regulated frataxin is rescued by means of human frataxin. The rescue is fully dependent on the human frataxin being imported into the trypanosome mitochondrion. Processing of the imported protein by mitochondrial processing peptidase can be blocked by mutations in the signal peptide, as in human cells. Although in human cells frataxin must be processed to execute its function, the same protein in the T. brucei mitochondrion is functional even in the absence of processing. Our results illuminate remarkable conservation of the mechanisms of mitochondrial protein import and processing.

Biology Centre Institute of Parasitology Czech Academy of Sciences and Faculty of Natural Sciences University of South Bohemia 37005 Ceské Budejovice Czech Republic

Zobrazit více v PubMed

Lukeš J, Hashimi H, Zíková A. Unexplained complexity of the mitochondrial genome and transcriptome in kinetoplastid flagellates. Curr Genet. 2005;48:277–299. PubMed

Keeling PJ, et al. The tree of eukaryotes. Trends Ecol Evol. 2005;20:670–676. PubMed

Bulteau A-L, et al. Frataxin acts as an iron chaperone protein to modulate mitochondrial aconitase activity. Science. 2004;305:242–245. PubMed

González-Cabo P, Vazquez-Manrique RP, García-Gimeno MA, Sanz P, Palau F. Frataxin interacts functionally with mitochondrial electron transport chain proteins. Hum Mol Genet. 2005;14:2091–2098. PubMed

Bencze KZ, et al. The structure and function of frataxin. Crit Rev Biochem Mol Biol. 2006;41:269–291. PubMed PMC

Campuzano V, et al. Frataxin is reduced in Friedreich ataxia patients and is associated with mitochondrial membranes. Hum Mol Genet. 1997;6:1771–1780. PubMed

Gakh O, et al. Mitochondrial iron detoxification is a primary function of frataxin that limits oxidative damage and preserves cell longevity. Hum Mol Genet. 2006;15:467–479. PubMed

Johnson DC, Dean DR, Smith AD, Johnson MK. Structure, function, and formation of biological iron-sulfur clusters. Annu Rev Biochem. 2005;74:247–281. PubMed

Lill R, Muhlenhoff U. Maturation of iron-sulfur proteins in eukaryotes: Mechanisms, connected processes, and diseases. Annu Rev Biochem. 2008;77:669–700. PubMed

Cavadini P, Adamec J, Taroni F, Gakh O, Isaya G. Two-step processing of human frataxin by mitochondrial processing peptidase. Precursor and intermediate forms are cleaved at different rates. J Biol Chem. 2000;275:41469–41475. PubMed

Lesuisse E, et al. Iron use for haeme synthesis is under control of the yeast frataxin homologue (Yfh1) Hum Mol Genet. 2003;12:879–889. PubMed

Cook JD, et al. Monomeric yeast frataxin is an iron binding protein. Biochemistry. 2006;45:7767–7777. PubMed PMC

Busi MV, et al. Deficiency of Arabidopsis thaliana frataxin alters activity of mitochondrial Fe-S proteins and induces oxidative stress. Plant J. 2006;48:873–882. PubMed

Long S, et al. Ancestral roles of eukaryotic frataxin: Mitochondrial frataxin function and heterologous expression of hydrogenosomal Trichomonas homologs in trypanosomes. Mol Microbiol. 2008;69:94–109. PubMed

Dolezal P, et al. Frataxin, a conserved mitochondrial protein, in the hydrogenosome of Trichomonas vaginalis. Eukaryot Cell. 2007;6:1431–1438. PubMed PMC

Martelli A, et al. Frataxin is essential for extramitochondrial Fe-S cluster proteins in mammalian tissues. Hum Mol Genet. 2007;16:2651–2658. PubMed

Rouault TA, Tong WH. Iron-sulphur cluster biogenesis and mitochondrial iron homeostasis. Nat Rev Mol Cell Biol. 2005;6:345–351. PubMed

Condo I, et al. In vivo maturation of human frataxin. Hum Mol Genet. 2007;16:1534–1540. PubMed

Smíd O, et al. Knockdowns of mitochondrial iron-sulfur cluster assembly proteins IscS and IscU down-regulate the active mitochondrion of procyclic Trypanosoma brucei. J Biol Chem. 2006;281:28679–28686. PubMed

Priest JW, Hajduk SL. In vitro import of the Rieske iron-sulfur protein by trypanosome mitochondria. J Biol Chem. 1996;271:20060–20069. PubMed

Hausler T, Stierhof Y-D, Blattner J, Clayton C. Conservation of mitochondrial targeting sequence function in mitochondrial and hydrogenosomal proteins from the early-branching eukaryotes Crithidia, Trypanosoma and Trichomonas. Eur J Cell Biol. 1997;73:240–251. PubMed

Uboldi AD, et al. A mitochondrial protein affects cell morphology, mitochondrial segregation and virulence in Leishmania. Int J Parasitol. 2006;36:1499–1514. PubMed

Dolezal P, et al. Giardia mitosomes and trichomonad hydrogenosomes share a common mode of protein targeting. Proc Natl Acad Sci USA. 2005;102:10924–10929. PubMed PMC

Tovar J, Fischer A, Clark CG. The mitosome, a novel organelle related to mitochondria in the amitochondrial parasite Entamoeba histolytica. Mol Microbiol. 1999;31:1013–1021. PubMed

Dolezal P, Likic V, Tachezy J, Lithgow T. Evolution of the molecular machines for protein import into mitochondria. Science. 2006;313:314–318. PubMed

Burri L, Keeling PJ. Protein targeting in parasites with cryptic mitochondria. Int J Parasitol. 2007;37:265–272. PubMed

Schneider A, Bursac D, Lithgow T. The direct route: A simplified pathway for protein import into the mitochondrion of trypanosomes. Trends Cell Biol. 2008;18:12–18. PubMed

Singha UK, et al. Characterization of the mitochondrial inner membrane protein translocator Tim17 from Trypanosoma brucei. Mol Biochem Parasitol. 2008;159:30–43. PubMed PMC

Gentle IE, et al. Conserved motifs reveal details of ancestry and structure in the small TIM chaperones of the mitochondrial intermembrane space. Mol Biol Evol. 2007;24:1149–1160. PubMed

Neupert W, Herrmann JM. Translocation of proteins into mitochondria. Annu Rev Biochem. 2007;76:723–749. PubMed

Acquaviva F, et al. Extramitochondrial localization of frataxin and its association with IscU1 during enterocyte-like differentiation of the human colon adenocarcinoma cell line Caco-2. J Cell Sci. 2005;118:3917–3924. PubMed

Lu C, Cortopassi G. Frataxin knockdown causes loss of cytoplasmic iron-sulfur cluster functions, redox alterations and induction of heme transcripts. Arch Biochem Biophys. 2006;457:111–122. PubMed PMC

Condo I, Ventura N, Malisan F, Tomassini B, Testi R. A pool of extramitochondrial frataxin that promotes cell survival. J Biol Chem. 2006;281:16750–16756. PubMed

Goldberg AV, et al. Localization and functionality of microsporidian iron- sulfur cluster assembly. Nature. 2008;452:624–628. PubMed

Stehling O, Elsasser HP, Bruckel B, Muhlenhoff U, Lill R. Iron-sulfur protein maturation in human cells: Evidence for a function of frataxin. Hum Mol Genet. 2004;13:3007–3015. PubMed

Seznec H, et al. Friedreich ataxia: The oxidative stress paradox. Hum Mol Genet. 2005;14:463–474. PubMed

Brinkmann H, Philippe H. The diversity of eukaryotes and the root of the eukaryotic tree. Adv Exp Med Biol. 2007;607:20–37. PubMed

Berriman M, et al. The genome of the African trypanosome Trypanosoma brucei. Science. 2005;309:416–422. PubMed

Rusconi F, Durand-Dubief M, Bastin P. Functional complementation of RNA interference mutants in trypanosomes. BMC Biotechnol. 2005;5 Art No 6. PubMed PMC

Determinism and contingencies shaped the evolution of mitochondrial protein import

ZapE/Afg1 interacts with Oxa1 and its depletion causes a multifaceted phenotype

Branched late-steps of the cytosolic iron-sulphur cluster assembly machinery of Trypanosoma brucei

Fe-S cluster assembly in the supergroup Excavata

Trypanosomal mitochondrial intermediate peptidase does not behave as a classical mitochondrial processing peptidase

Mitochondrial and nucleolar localization of cysteine desulfurase Nfs and the scaffold protein Isu in Trypanosoma brucei

An Advanced System of the Mitochondrial Processing Peptidase and Core Protein Family in Trypanosoma brucei and Multiple Origins of the Core I Subunit in Eukaryotes

The Fe/S cluster assembly protein Isd11 is essential for tRNA thiolation in Trypanosoma brucei