A possible mitochondrial gene in the early-branching amitochondriate protist
            <i>Trichomonas vaginalis</i>

Roger, Andrew J.; Clark, C. Graham; Doolittle, W. Ford

doi:10.1073/pnas.93.25.14618

Cited by 165 publications

(92 citation statements)

References 29 publications

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“…If one assumes a mitochondrial origin for trichomonad hydrogenosomes [22], a scenario which has recently received direct support from protein coding genes [23][24][25][26], then one can speculate that genome loss is through redundancy caused by change of function. Mitochondrial DNA encodes rRNA and tRNA components of the mitochondrial protein synthesizing machinery, which function is to translate a small number of mtDNA-encoded mRNAs that specify essential polypeptide components of the mitochondrial electron transport chain [27,28].…”

Section: Resultsmentioning

confidence: 99%

Hydrogenosomes in the anaerobic fungus Neocallimastix frontalis have a double membrane but lack an associated organelle genome

et al. 1997

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The presence of hydrogenosomes in phylogenetically distinct anaerobic eukaryotes implies that they have been acquired independently, and previously reported differences in ultrastructure among taxa have suggested that some hydrogenosomes have different origins. Of particular interest are reports that Neocallimastix frontalis hydrogenosomes resemble microbodies in possessing a single membrane, in contrast to those in ciliates and trichomonads which have two and thus resemble mitochondria. In this investigation we have clearly demonstrated that N. frontalis hydrogenosomes possess two, rather than one, closely apposed membranes and in some preparations cristae-like structures were observed. These observations have led us to reject the microbody hypothesis and provide some indirect support for a possible mitochondrion origin as proposed for other hydrogenosomes. N. frontalis hydrogenosomes were shown to lack an associated genome as previously demonstrated for trichomonad hydrogenosomes. This might be explained by assuming that a mitochondrial genome encoding proteins for aerobic function is no longer necessary for either organelle.

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Section: Resultsmentioning

confidence: 99%

Hydrogenosomes in the anaerobic fungus Neocallimastix frontalis have a double membrane but lack an associated organelle genome

et al. 1997

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“…Phylogenetic analyses of heat shock proteins in hydrogenosome-containing T. vaginalis (5,11,16,41) as well as in Giardia lamblia (42) and Entamoeba histolytica (7), two eukaryotes that harbor neither organelle but appear to have lost mitochondria secondarily, indicate that these proteins are closely related to mitochondrial heat shock proteins. These findings, however, are still compatible with independent symbioses of two related proteobacteria (47) bearing similar heat shock proteins, which are indeed still conserved in their modern-day relatives.…”

Section: Discussionmentioning

confidence: 99%

“…Recently, molecular analyses of hydrogenosomal heat shock proteins from Trichomonas vaginalis (5,11,16,41) have demonstrated a close phylogenetic relationship between the nuclear genes encoding these proteins and their mitochondrial counterparts, suggesting a common symbiotic origin for the two organelles. The latest theory is one based on the metabolic force behind the symbiotic event-the hydrogen hypothesis (29).…”

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confidence: 99%

Presence of a Member of the Mitochondrial Carrier Family in Hydrogenosomes: Conservation of Membrane-Targeting Pathways between Hydrogenosomes and Mitochondria

Dyall¹,

Koehler

Delgadillo-Correa³

et al. 2000

Molecular and Cellular Biology

105

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A number of microaerophilic eukaryotes lack mitochondria but possess another organelle involved in energy metabolism, the hydrogenosome. Limited phylogenetic analyses of nuclear genes support a common origin for these two organelles. We have identified a protein of the mitochondrial carrier family in the hydrogenosome of Trichomonas vaginalis and have shown that this protein, Hmp31, is phylogenetically related to the mitochondrial ADP-ATP carrier (AAC). We demonstrate that the hydrogenosomal AAC can be targeted to the inner membrane of mitochondria isolated from Saccharomyces cerevisiae through the Tim9-Tim10 import pathway used for the assembly of mitochondrial carrier proteins. Conversely, yeast mitochondrial AAC can be targeted into the membranes of hydrogenosomes. The hydrogenosomal AAC contains a cleavable, N-terminal presequence; however, this sequence is not necessary for targeting the protein to the organelle. These data indicate that the membrane-targeting signal(s) for hydrogenosomal AAC is internal, similar to that found for mitochondrial carrier proteins. Our findings indicate that the membrane carriers and membrane protein-targeting machinery of hydrogenosomes and mitochondria have a common evolutionary origin. Together, they provide strong evidence that a single endosymbiont evolved into a progenitor organelle in early eukaryotic cells that ultimately give rise to these two distinct organelles and support the hydrogen hypothesis for the origin of the eukaryotic cell.

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“…In lieu of this, we and others have attempted to define the relationship between trichomonad hydrogenosomes and mitochondria by examining the origin of their chaperonins, metabolic enzymes, and membrane proteins. Chaperonin genes, specifically heat shock protein (Hsp) 1 70, cpn60, and Hsp10 (11)(12)(13)(14), and the IscS enzyme, involved in FeS cluster formation (15) appear to have a mitochondrial origin. However, analyses of metabolic enzymes such as hydrogenase (16,17), which is typically found in anaerobic bacteria, present a far more ambiguous picture.…”

mentioning

confidence: 99%

Trichomonas vaginalis Hmp35, a Putative Pore-forming Hydrogenosomal Membrane Protein, Can Form a Complex in Yeast Mitochondria

Dyall¹,

Lester

Schneider

et al. 2003

Journal of Biological Chemistry

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An abundant integral membrane protein, Hmp35, has been isolated from hydrogenosomes of Trichomonas vaginalis. This protein has no known homologue and exists as a stable 300-kDa complex, termed HMP35, in membranes of the hydrogenosome. By using blue native gel electrophoresis, we found the HMP35 complex to be stable in 2 M NaCl and up to 5 M urea. The endogenous Hmp35 protein was largely protease-resistant. The protein has a predominantly ␤-sheet structure and predicted transmembrane domains that may form a pore. Interestingly, the protein has a high number of cysteine residues, some of which are arranged in motifs that resemble the RING finger, suggesting that they could be coordinating zinc or another divalent cation. Our data show that Hmp35 forms one intramolecular but no intermolecular disulfide bonds. We have isolated the HMP35 complex by expressing a His-tagged Hmp35 protein in vivo followed by purification with nickel-agarose beads. The purified 300-kDa complex consists of mostly Hmp35 with lesser amounts of 12-, 25-27-, and 32-kDa proteins. The stoichiometry of proteins in the complex indicates that Hmp35 exists as an oligomer. Hmp35 can be targeted heterologously into yeast mitochondria, despite the lack of homology with any yeast protein, demonstrating the compatibility of mitochondrial and hydrogenosomal protein translocation machineries.Trichomonas vaginalis is a deep-branching protist that lacks archetypal eukaryotic "aerobic" organelles, specifically mitochondria and peroxisomes. This microaerophilic human-infective parasite carries out fermentative carbohydrate metabolism within hydrogenosomes. Hydrogenosomes are bounded by double membranes and produce ATP by substrate level phosphorylation (1). Hydrogenosomes are also found in certain chytrids, ciliates, and fungi, in lineages that are phylogenetically distant to the Parabasalian lineage to which trichomonads belong (1-4). Currently, several lines of evidence support a common endosymbiotic ancestry for hydrogenosomes and mitochondria, despite their distinct metabolic pathways (3,5,6). Although the origin of hydrogenosomes within ciliate and fungi lineages is debated, these lineages branch with mitochondria-containing groups and the hydrogenosomes confined therein exhibit strong similarity to ciliate and fungal mitochondria (7,8).Trichomonad hydrogenosomes, on the other hand, are markedly less similar to mitochondria. These organelles lack a genome (9) which would have provided a means to investigate their endosymbiotic origin as has been elegantly and convincingly done for mitochondria (10). In lieu of this, we and others have attempted to define the relationship between trichomonad hydrogenosomes and mitochondria by examining the origin of their chaperonins, metabolic enzymes, and membrane proteins. Chaperonin genes, specifically heat shock protein (Hsp) 1 70, cpn60,, and the IscS enzyme, involved in FeS cluster formation (15) appear to have a mitochondrial origin. However, analyses of metabolic enzymes such as hydrogenase (16,17), which is typi...

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A possible mitochondrial gene in the early-branching amitochondriate protist Trichomonas vaginalis

Cited by 165 publications

References 29 publications

Hydrogenosomes in the anaerobic fungus Neocallimastix frontalis have a double membrane but lack an associated organelle genome

Hydrogenosomes in the anaerobic fungus Neocallimastix frontalis have a double membrane but lack an associated organelle genome

Presence of a Member of the Mitochondrial Carrier Family in Hydrogenosomes: Conservation of Membrane-Targeting Pathways between Hydrogenosomes and Mitochondria

Trichomonas vaginalis Hmp35, a Putative Pore-forming Hydrogenosomal Membrane Protein, Can Form a Complex in Yeast Mitochondria

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