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Functional frataxin homologue in hydrogenosomes of Trichomonas vaginalis
Author(s) -
DOLEZAL P.,
DANCIS A.,
EMBLEY M.,
TACHEZY J.
Publication year - 2005
Publication title -
journal of eukaryotic microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.067
H-Index - 77
eISSN - 1550-7408
pISSN - 1066-5234
DOI - 10.1111/j.1550-7408.2005.05202003_5_5.x
Subject(s) - frataxin , biology , aconitase , mitochondrion , complementation , biochemistry , iron–sulfur cluster , microbiology and biotechnology , gene , mutant , enzyme
The cellular structure of Trichomonas vaginalis substantially differs from other eukaryotes. Instead of mitochondria it possesses hydrogenosomes where key metabolic reactions are mediated by FeS proteins. The gene expression and the activity of FeS proteins is fully dependent on the iron availability. Although hydrogenosomes contain a high amount of iron, there is no information about hydrogenosomal iron homeostasis and FeS cluster formation. In mitochondria, frataxin plays an unclear role in iron metabolism. The deficiency of frataxin in human causes Friedreich's ataxia, which is associated with an increased level of mitochondrial iron. It has been suggested that frataxin is involved in various functions such as FeS cluster formation or iron storage. We cloned T. vaginalis frataxin homologue (TvFTX) coding for a protein of 121 amino acids. Although lacking transcription initiator element in 5′UTR region, the expression of tvftx was verified by a nuclear run‐on assay. Moreover, the gene upregulation in iron deficiency was shown. The N‐terminal part of TvFTX contains an extension similar to presequences targeting proteins to hydrogenosomes and mitochondria. To identify its cellular localization we transfected T. vaginalis with TvFTX fused to HA tag. The immunodetection of HA tag specifically labeled hydrogenosomes and the corresponding cellular fraction. The hydrogenosomal targeting sequence however does not support the translocation into yeast mitochondria. Thus for the complementation of yeast frataxin homologue (YFH1) a mitochondrial targeting sequence is required. When expressed in mitochondria of δYFH1 cells TvFTX complements the mutant growth defect and restores the activity of aconitase (iron‐sulfur protein). Together with recent characterization of T. vaginalis cystein desulfurase these data indicate the conserved role of hydrogenosomes and mitochondria in FeS cluster assembly.