The majority of established model organisms belong to the supergroup Opisthokonta, which includes yeasts and animals. While enlightening, this focus has neglected protists, organisms that represent the bulk of eukaryotic diversity and are often regarded as primitive eukaryotes. One of these is the "supergroup" Excavata, which comprises unicellular flagellates of diverse lifestyles and contains species of medical importance, such as Trichomonas, Giardia, Naegleria, Trypanosoma and Leishmania. Excavata exhibits a continuum in mitochondrial forms, ranging from classical aerobic, cristae-bearing mitochondria to mitochondria-related organelles, such as hydrogenosomes and mitosomes, to the extreme case of a complete absence of the organelle. All forms of mitochondria house a machinery for the assembly of Fe-S clusters, ancient cofactors required in various biochemical activities needed to sustain every extant cell. In this review, we survey what is known about the Fe-S cluster assembly in the supergroup Excavata. We aim to bring attention to the diversity found in this group, reflected in gene losses and gains that have shaped the Fe-S cluster biogenesis pathways.

• Klíčová slova
• Evolution, Excavata, Fe–S cluster, Mitochondria,
• MeSH
• Eukaryota cytologie   metabolismus   MeSH
• mitochondrie metabolismus   MeSH
• proteiny obsahující železo a síru metabolismus   MeSH
• železo metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• proteiny obsahující železo a síru MeSH
• železo MeSH

Upon their translocation into the mitochondrial matrix, the N-terminal pre-sequence of nuclear-encoded proteins undergoes cleavage by mitochondrial processing peptidases. Some proteins require more than a single processing step, which involves several peptidases. Down-regulation of the putative Trypanosoma brucei mitochondrial intermediate peptidase (MIP) homolog by RNAi renders the cells unable to grow after 48 hours of induction. Ablation of MIP results in the accumulation of the precursor of the trypanosomatid-specific trCOIV protein, the largest nuclear-encoded subunit of the cytochrome c oxidase complex in this flagellate. However, the trCOIV precursor of the same size accumulates also in trypanosomes in which either alpha or beta subunits of the mitochondrial processing peptidase (MPP) have been depleted. Using a chimeric protein that consists of the N-terminal sequence of a putative subunit of respiratory complex I fused to a yellow fluorescent protein, we assessed the accumulation of the precursor protein in trypanosomes, in which RNAi was induced against the alpha or beta subunits of MPP or MIP. The observed accumulation of precursors indicates MIP depletion affects the activity of the cannonical MPP, or at least one of its subunits.

• MeSH
• down regulace MeSH
• fluorescenční mikroskopie MeSH
• fylogeneze MeSH
• malá interferující RNA metabolismus   MeSH
• metaloendopeptidasy antagonisté a inhibitory   klasifikace   genetika   metabolismus   MeSH
• mitochondrie enzymologie   MeSH
• MPP peptidasa MeSH
• podjednotky proteinů antagonisté a inhibitory   genetika   metabolismus   MeSH
• respirační komplex IV metabolismus   MeSH
• RNA interference MeSH
• sekvence aminokyselin MeSH
• substrátová specifita MeSH
• Trypanosoma brucei brucei metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• malá interferující RNA MeSH
• metaloendopeptidasy MeSH
• mitochondrial intermediate peptidase MeSH Prohlížeč
• podjednotky proteinů MeSH
• respirační komplex IV MeSH

Lipophilic bisphosphonium salts are among the most promising antiprotozoal leads currently under investigation. As part of their preclinical evaluation we here report on their mode of action against African trypanosomes, the etiological agents of sleeping sickness. The bisphosphonium compounds CD38 and AHI-9 exhibited rapid inhibition of Trypanosoma brucei growth, apparently the result of cell cycle arrest that blocked the replication of mitochondrial DNA, contained in the kinetoplast, thereby preventing the initiation of S-phase. Incubation with either compound led to a rapid reduction in mitochondrial membrane potential, and ATP levels decreased by approximately 50% within 1 h. Between 4 and 8 h, cellular calcium levels increased, consistent with release from the depolarized mitochondria. Within the mitochondria, the Succinate Dehydrogenase complex (SDH) was investigated as a target for bisphosphonium salts, but while its subunit 1 (SDH1) was present at low levels in the bloodstream form trypanosomes, the assembled complex was hardly detectable. RNAi knockdown of the SDH1 subunit produced no growth phenotype, either in bloodstream or in the procyclic (insect) forms and we conclude that in trypanosomes SDH is not the target for bisphosphonium salts. Instead, the compounds inhibited ATP production in intact mitochondria, as well as the purified F1 ATPase, to a level that was similar to 1 mM azide. Co-incubation with azide and bisphosphonium compounds did not inhibit ATPase activity more than either product alone. The results show that, in T. brucei, bisphosphonium compounds do not principally act on succinate dehydrogenase but on the mitochondrial FoF1 ATPase.

• Klíčová slova
• FoF1 ATPase, Mitochondrion, Phosphonium salt, SDH complex, Succinate dehydrogenase, Trypanosoma brucei,
• MeSH
• adenosintrifosfát metabolismus   MeSH
• azidy farmakologie   MeSH
• buněčné linie MeSH
• membránový potenciál mitochondrií účinky léků   MeSH
• mitochondriální DNA metabolismus   MeSH
• mitochondrie účinky léků   genetika   metabolismus   MeSH
• organofosforové sloučeniny chemie   farmakologie   MeSH
• protonové ATPasy metabolismus   MeSH
• RNA interference MeSH
• sukcinátdehydrogenasa metabolismus   MeSH
• trypanocidální látky farmakologie   MeSH
• Trypanosoma brucei brucei cytologie   účinky léků   růst a vývoj   MeSH
• trypanozomóza africká parazitologie   MeSH
• vápník metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• adenosintrifosfát MeSH
• azidy MeSH
• mitochondriální DNA MeSH
• organofosforové sloučeniny MeSH
• protonové ATPasy MeSH
• sukcinátdehydrogenasa MeSH
• trypanocidální látky MeSH
• vápník MeSH

In the infectious stage of Trypanosoma brucei, an important parasite of humans and livestock, the mitochondrial (mt) membrane potential (Δψm) is uniquely maintained by the ATP hydrolytic activity and subsequent proton pumping of the essential FoF1-ATPase. Intriguingly, this multiprotein complex contains several trypanosome-specific subunits of unknown function. Here, we demonstrate that one of the largest novel subunits, ATPaseTb2, is membrane-bound and localizes with monomeric and multimeric assemblies of the FoF1-ATPase. Moreover, RNAi silencing of ATPaseTb2 quickly leads to a significant decrease of the Δψm that manifests as a decreased growth phenotype, indicating that the FoF1-ATPase is impaired. To further explore the function of this protein, we employed a trypanosoma strain that lacks mtDNA (dyskinetoplastic, Dk) and thus subunit a, an essential component of the proton pore in the membrane Fo-moiety. These Dk cells generate the Δψm by combining the hydrolytic activity of the matrix-facing F1-ATPase and the electrogenic exchange of ATP4- for ADP3- by the ATP/ADP carrier (AAC). Surprisingly, in addition to the expected presence of F1-ATPase, the monomeric and multimeric FoF1-ATPase complexes were identified. In fact, the immunoprecipitation of a F1-ATPase subunit demonstrated that ATPaseTb2 was a component of these complexes. Furthermore, RNAi studies established that the membrane-bound ATPaseTb2 subunit is essential for maintaining normal growth and the Δψm of Dk cells. Thus, even in the absence of subunit a, a portion of the FoF1-ATPase is assembled in Dk cells.

• MeSH
• geneticky modifikované organismy MeSH
• kultivované buňky MeSH
• lidé MeSH
• membránové proteiny fyziologie   MeSH
• mitochondriální DNA genetika   MeSH
• mitochondrie genetika   metabolismus   MeSH
• podjednotky proteinů fyziologie   MeSH
• protonové ATPasy fyziologie   MeSH
• skot MeSH
• Trypanosoma brucei brucei * genetika   metabolismus   patogenita   ultrastruktura   MeSH
• trypanozomóza africká krev   parazitologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• skot MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• membránové proteiny MeSH
• mitochondriální DNA MeSH
• podjednotky proteinů MeSH
• protonové ATPasy MeSH