Ribosomes from trichomonad protozoa have prokaryotic characteristics

Champney, W. Scott; Chittum, Harold S.; Samuels, Richard Ian

doi:10.1016/0020-711x(92)90383-c

Cited by 15 publications

(5 citation statements)

References 37 publications

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“…Trichomonads consistently represent one of the earliest branches in SSU rDNA trees constructed using different taxa or methods (Leipe et al 1993;Gunderson et al 1995;Philippe & Adoutte 1995) (see figure 2). The presence of 70S ribosomes in Microspora and trichomonads (Ishihara & Hayashi 1968;Champney et al 1992) lends further support to the hypothesis that they originate early. Detailed analyses of cpn-60 sequences did not provide un equivocal support from bootstrapping for Trichomonas branching deeper than Trypanosoma, which one might expect if it's position in SSU rDNA trees (figure 2) is an accurate reflection of its history.…”

Section: Discussionsupporting

confidence: 60%

“…One possible evolutionary inference is that all three of these protist groups are primitively amitochondriate, having diverged from the main eucaryote trunk before this endosymbiosis (Patterson & Sogin 1993). In addition, Trichomonads and Microspora possess 70S rather than 80S ribosomes, which has been interpreted as retention of an ancestral state present in prokaryote outgroups, providing additional support for their divergence early in eucaryote history (Champney et al 1992;Cavalier-Smith 1993 a). The relative order of branching of these taxa has not been clearly resolved, as it varies with taxon composition or method of analysis, and all three * Author to whom correspondence should be addressed.…”

Section: Introductionmentioning

confidence: 99%

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Molecular data suggest an early acquisition of the mitochondrion endosymbiont

Horner

Hirt

Kilvington

et al. 1996

Proc. R. Soc. Lond. B

146

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The three deepest branching eucaryotic lineages in small subunit ribosomal RNA phylogenies are the amitochondriate Microspora, Metamonada and Parabasala. They are followed by either the Euglenozoa (e.g. Euglena and Trypanosoma) or the Percolozoa as the first mitochondria-containing eucaryotes. To investigate the hypothesis of an even earlier timing of the mitochondrion endosymbiosis we have amplified a partial cpn-60 coding region from the parabasalid Trichomonas vaginalis and the first such sequence from a percolozoan, Naegleria fowleri. Analysis of predicted protein sequences reveals a high degree of sequence similarity (> or = 40%) with a selection of published bacterial and mitochondrial cpn-60s for both taxa. Both sequences were recovered within a strongly supported monophyletic group, otherwise defined by mitochondrial sequences, which systematically clustered with alpha-proteobacteria. These results provide compelling evidence that the ancestor of T. vaginalis once contained the endosymbiont which gave rise to mitochondria, and suggest that this symbiosis probably occurred before the Trichomonas lineage diverged from the main eukaryote trunk. It also makes feasible the published hypothesis that the Trichomonas hydrogenosome might represent a biochemically modified mitochondrion. Analysis of the N. fowleri cpn-60 did not support the hypothesis that the mitochondrion-containing Percolozoa represent an earlier branch in the cpn-60 tree than Trichomonas or Trypanosoma.

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Section: Discussionsupporting

confidence: 60%

Section: Introductionmentioning

confidence: 99%

Molecular data suggest an early acquisition of the mitochondrion endosymbiont

Horner

Hirt

Kilvington

et al. 1996

Proc. R. Soc. Lond. B

146

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“…The viral host Giardia is known to possess the translation machinery with many unusual features, such as the involvement of a 70S instead of a 80S ribosome [48] and the translation initiation factors that are either missing or structurally divergent as compared to that of the higher eukaryotes [49]. To learn whether the GLV IRES may function in a novel mechanism of translation initiation due to the unusual translation machinery in Giardia , we tested its function in rabbit reticulocyte lysates (RRL) and found significantly reduced IRES activity with very simple structural requirement.…”

Section: Introductionmentioning

confidence: 99%

Giardiavirus Internal Ribosome Entry Site Has an Apparently Unique Mechanism of Initiating Translation

Garlapati

Wang

2009

PLoS ONE

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Giardiavirus (GLV) utilizes an internal ribosome entry site (IRES) for translation initiation in the early branching eukaryote Giardia lamblia. Unlike most of the viral IRESs among higher eukaryotes, which localize primarily within the 5′-untranslated region (UTR), the GLV IRES comprises 253 nts of 5′UTR and the initial 264 nts in the open-reading-frame (ORF). To test if GLV IRES also functions in higher eukaryotic systems, we examined it in rabbit reticulocyte lysate (RRL) and found that it functions much less efficiently than the IRES from the Encephalomyocarditis virus (EMCV) or Cricket paralysis virus (CrPV). In contrast, both EMCV-IRES and CrPV-IRESs were inactive in transfected Giardia cells. Structure-function analysis indicated that only the stem-loop U5 from the 5′UTR and the stem-loop I plus the downstream box (Dbox) from the ORF of GLV IRES are required for limited IRES function in RRL. Edeine, a translation initiation inhibitor, did not significantly affect the function of GLV IRES in either RRL or Giardia, indicating that a pre-initiation complex is not required for GLV IRES–mediated translation initiation. However, the small ribosomal subunit purified from Giardia did not bind to GLV IRES, indicating that additional protein factors may be necessary. A member of the helicase family IBP1 and two known viral IRES binding proteins La autoantigen and SRp20 have been identified in Giardia that bind to GLV IRES in vitro. These three proteins could be involved in facilitating small ribosome recruitment for initiating translation.

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mentioning

confidence: 99%

“…The trichomonads possess hydrogenosomes [6, 231, lack mitochondria and peroxisomes and have 70s ribosomes [9] like the microsporidia [30] and the prokaryotes. Therefore, they may be one of the earliest emerging eukaryotic groups [7, 20, 261. This was confirmed by analysis of the small subunit ribosomal DNA (SSU rDNA) of Trichomonas vuginulis [27] and Tritrichomonas foetus [7, 8, 20, 261. The large subunit ribosomal DNA (LSU rDNA) of various trichomonads has been partly sequenced showing Trichomitus I To whom correspondence should be addressed.…”

mentioning

confidence: 99%

Culture and Phylogenetic Characterization of Trichomitus trypanoides Duboscq & Grassè 1924, n. comb.: a Trichomonad Flagellate Isolated from the Hindgut of the Termite Reticulitermes santonensis Feytaud

Berchtold

Breunig

König

1995

J Eukaryotic Microbiology

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A trichomonad flagellate strain R1 was isolated from the hindgut contents of the termite Reticulitermes santonensis Feytaud. The flagellate was cultivated at 28 degrees C in anaerobic medium containing yeast extract, minerals and vitamins. The isolate fed on living bacteria. It showed the typical morphological and ultrastructural features of the trichomonads, closely resembling Trichomitus trypanoides. In order to determine its phylogenetic position the small subunit ribosomal DNA (SSU rDNA) of the flagellate was amplified in vitro using the polymerase chain reaction (PCR), cloned in a plasmid vector and sequenced. Comparison of the obtained sequence with so far available SSU rRNA/rDNA sequences showed strongest similarity (89%) to the sequence of Tritrichomonas foetus. The phylogenetic analysis with parsimony and distance matrix methods placed Trichomitus trypanoides strain R1 near by the root of the phylogenetically so far analyzed eukaryotic organisms. This confirms that termites harbour hindgut symbionts, which originate from very early evolved eukaryotes.

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Ribosomes from trichomonad protozoa have prokaryotic characteristics

Cited by 15 publications

References 37 publications

Molecular data suggest an early acquisition of the mitochondrion endosymbiont

Molecular data suggest an early acquisition of the mitochondrion endosymbiont

Giardiavirus Internal Ribosome Entry Site Has an Apparently Unique Mechanism of Initiating Translation

Culture and Phylogenetic Characterization of Trichomitus trypanoides Duboscq & Grassè 1924, n. comb.: a Trichomonad Flagellate Isolated from the Hindgut of the Termite Reticulitermes santonensis Feytaud

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