NADH-ubiquinone oxidoreductase activity in the kinetoplasts of the plant trypanosomatid Phytomonas serpens

González‐Halphen, Diego; Maslov, Dmitri

doi:10.1007/s00436-003-1058-4

Cited by 20 publications

(26 citation statements)

References 38 publications

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“…It has been proposed that, when present, the trypanosomatid complex does not perform proton-pumping across the inner membrane but is only involved in regeneration of mitochondrial NAD + (Opperdoes and Michels, 2008). An enzymatically active NADH dehydrogenase complex has been detected in T. brucei (Fang et al, 2001) and Phytomonas serpens (Čermáková et al, 2007; González-Halphen and Maslov, 2004), organisms that either temporarily (bloodstream trypanosomes) (Vickerman, 1994) or permanently ( Phytomonas spp.) (Nawathean and Maslov, 2000) lack a cytochrome-mediated electron transport chain.…”

Section: Discussionmentioning

confidence: 99%

RNA editing and mitochondrial activity in promastigotes and amastigotes of Leishmania donovani

Neboháčová

Kim

Simpson

et al. 2009

International Journal for Parasitology

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Kinetoplast maxicircle DNA sequence organization was investigated in Leishmania donovani, strain 1S LdBob. Gene arrangement in the coding (conserved) region of the maxicircle is collinear with that of most trypanosomatids, with individual genes showing 80-90% nucleotide identity to Leishmania tarentolae, strain UC. The notable exception was an integration of a full-size minicircle sequence in the ND1 gene coding region found in L. donovani. Editing patterns of the mitochondrial mRNAs investigated also followed L. tarentolae UC patterns, including productive editing of the components of respiratory complexes III, IV and V, and ribosomal protein S12 (RPS12), as well as the lack of productive editing in five out of six pan-edited cryptogenes (ND3, ND8, ND9, G3, G4) found in these species. Several guide RNAs for the editing events were localized in minicircles and maxicircles in the locations that are conserved between the species. Mitochondrial activity, including rates of oxygen consumption, the presence and the levels of respiratory complexes and their individual subunits and the steady-state levels of several mitochondrial-encoded mRNAs were essentially the same in axenically grown amastigotes and in promastigotes of L. donovani. However, some modulation of mitochondrial activity between these developmental stages was suggested by the finding of an amastigote-specific component in Complex IV, a down-regulation of mitochondrial RNA-binding proteins (MRP) [define] and MRP-associated protein (MRP-AP) in amastigotes, and by variations in the levels of RPS12, ND3, ND9, G3 and G4 pre-edited transcripts.

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Section: Discussionmentioning

confidence: 99%

RNA editing and mitochondrial activity in promastigotes and amastigotes of Leishmania donovani

Neboháčová

Kim

Simpson

et al. 2009

International Journal for Parasitology

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“…Such a membrane gradient is required for the import of nuclear-encoded proteins into the hydrogenosome in the absence of a respiratory chain (Bradley et al 1997). Interestingly, mitochondria of the trypanosomatid Phytomonas serpens are similar to the T. vaginalis hydrogenosome, in the sense that they lack a respiratory chain but have retained a multimeric complex I with seemingly unique characteristics (González-Halphen and Maslov 2004;Cermakova et al 2007). Again, the function of this complex I is not known, but a role in maintaining the membrane potential is suspected (Nawathean and Maslov 2000;Cermakova et al 2007).…”

Section: Non-canonical Complex I In Eukaryotesmentioning

confidence: 94%

Eukaryotic complex I: functional diversity and experimental systems to unravel the assembly process

et al. 2008

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With more than 40 subunits, one FMN co-factor and eight FeS clusters, complex I or NADH:ubiquinone oxidoreductase is the largest multimeric respiratory enzyme in the mitochondria. In this review, we focus on the diversity of eukaryotic complex I. We describe the additional activities that have been reported to be associated with mitochondrial complex I and discuss their physiological significance. The recent identification of complex I-like enzymes in the hydrogenosome, a mitochondria-derived organelle is also discussed here. Complex I assembly in the mitochondrial inner membrane is an intricate process that requires the cooperation of the nuclear and mitochondrial genomes. The most prevalent forms of mitochondrial dysfunction in humans are deficiencies in complex I and remarkably, the molecular basis for 60% of complex I-linked defects is currently unknown. This suggests that mutations in yet-to-be-discovered assembly genes should exist. We review the different experimental systems for the study of complex I assembly. To our knowledge, in none of them, large screenings of complex I mutants have been performed. We propose that the unicellular green alga Chlamydomonas reinhardtii is a promising system for such a study. Complex I mutants can be easily scored on a phenotypical basis and a large number of transformants generated by insertional mutagenesis can be screened, which opens the possibility to find new genes involved in the assembly of the enzyme. Moreover, mitochondrial transformation, a recent technological advance, is now available, allowing the manipulation of all five complex I mitochondrial genes in this organism.

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“…The effect of relatively high concentrations of rotenone, an inhibitor of complex I, on procyclics in vivo was interpreted either as a proof of specific inhibition of this complex (Beattie and Howton, 1996; Tielens and Van Hellemond, 1998; Fang et al ., 2001) or as a non‐specific blockade of other activities (Hernandez and Turrens, 1998; Christmas and Turrens, 2000). Although a functional complex I remains to be purified and characterized, biochemical evidence provided recently (Gonzáles‐Halphen and Maslov, 2004) and the presence of putative homologues of mitochondrial and nuclear‐encoded subunits in the trypanosomatid genomes support its existence in procyclics.…”

Section: Introductionmentioning

confidence: 99%

Downregulation of the nuclear‐encoded subunits of the complexes III and IV disrupts their respective complexes but not complex I in procyclic Trypanosoma brucei

Horváth

Horáková

Dunajčíková

et al. 2005

Molecular Microbiology

107

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SummaryThe function, stability and mutual interactions of selected nuclear-encoded subunits of respiratory complexes III and IV were studied in the Trypanosoma brucei procyclics using RNA interference (RNAi). The growth rates and oxygen consumption of clonal cell lines of knock-downs for apocytochrome c 1 (apo c 1 ) and the Rieske Fe-S protein (Rieske) of complex III, and cytochrome c oxidase subunit 6 (cox6) of complex IV were markedly decreased after RNAi induction. Western analysis of mitochondrial lysates using specific antibodies confirmed complete elimination of the targeted proteins 4-6 days after induction. The Rieske protein was reduced in the apo c 1 knock-down and vice versa, indicating a mutual interdependence of these components of complex III. However, another subunit of complex IV remained at the wild-type level in the cox6 knock-down. As revealed by twodimensional blue native/SDS-PAGE electrophoresis, silencing of a single subunit resulted in the disruption of the respective complex, while the other complex remained unaffected. Membrane potential was reproducibly decreased in the knock-downs and the activities of complex III and/or IV, but not complex I, were drastically reduced, as measured by activity assays and histochemical staining. Using specific inhibitors, we have shown that in procyclics with depleted subunits of the respiratory complexes the flow of electrons was partially re-directed to the alternative č ě š Š š sˇČ eˇ oxidase. The apparent absence in T. brucei procyclics of a supercomplex composed of complexes I and III may represent an ancestral state of the respiratory chain.

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NADH-ubiquinone oxidoreductase activity in the kinetoplasts of the plant trypanosomatid Phytomonas serpens

Cited by 20 publications

References 38 publications

RNA editing and mitochondrial activity in promastigotes and amastigotes of Leishmania donovani

RNA editing and mitochondrial activity in promastigotes and amastigotes of Leishmania donovani

Eukaryotic complex I: functional diversity and experimental systems to unravel the assembly process

Downregulation of the nuclear‐encoded subunits of the complexes III and IV disrupts their respective complexes but not complex I in procyclic Trypanosoma brucei

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