Horváth, Anton* Dotaz Zobrazit nápovědu
Trypanosoma brucei is an important human pathogen. In this study, we have focused on the characterization of FtsH protease, ATP-dependent membrane-bound mitochondrial enzyme important for regulation of protein abundance. We have determined localization and orientation of all six putative T.brucei FtsH homologs in the inner mitochondrial membrane by in silico analyses, by immunofluorescence, and with protease assay. The evolutionary origin of these homologs has been tested by comparative phylogenetic analysis. Surprisingly, some kinetoplastid FtsH proteins display inverted orientation in the mitochondrial membrane compared to related proteins of other examined eukaryotes. Moreover, our data strongly suggest that during evolution the orientation of FtsH protease in T. brucei varied due to both loss and acquisition of the transmembrane domain.
- MeSH
- Arabidopsis klasifikace enzymologie genetika MeSH
- Euglena gracilis klasifikace enzymologie genetika MeSH
- Euglena longa klasifikace enzymologie genetika MeSH
- exprese genu MeSH
- fylogeneze MeSH
- izoenzymy chemie genetika metabolismus MeSH
- konzervovaná sekvence MeSH
- Leishmania major klasifikace enzymologie genetika MeSH
- lidé MeSH
- mitochondriální membrány chemie enzymologie MeSH
- mitochondriální proteiny chemie genetika metabolismus MeSH
- mitochondrie enzymologie genetika MeSH
- molekulární evoluce * MeSH
- myši MeSH
- proteasy chemie genetika metabolismus MeSH
- proteinové domény MeSH
- protozoální proteiny chemie genetika metabolismus MeSH
- Saccharomyces cerevisiae klasifikace enzymologie genetika MeSH
- Trypanosoma brucei brucei klasifikace enzymologie genetika MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- MeSH
- financování organizované MeSH
- Publikační typ
- abstrakty MeSH
The highly conserved ADP/ATP carrier (AAC) is a key energetic link between the mitochondrial (mt) and cytosolic compartments of all aerobic eukaryotic cells, as it exchanges the ATP generated inside the organelle for the cytosolic ADP. Trypanosoma brucei, a parasitic protist of medical and veterinary importance, possesses a single functional AAC protein (TbAAC) that is related to the human and yeast ADP/ATP carriers. However, unlike previous studies performed with these model organisms, this study showed that TbAAC is most likely not a stable component of either the respiratory supercomplex III+IV or the ATP synthasome but rather functions as a physically separate entity in this highly diverged eukaryote. Therefore, TbAAC RNA interference (RNAi) ablation in the insect stage of T. brucei does not impair the activity or arrangement of the respiratory chain complexes. Nevertheless, RNAi silencing of TbAAC caused a severe growth defect that coincides with a significant reduction of mt ATP synthesis by both substrate and oxidative phosphorylation. Furthermore, TbAAC downregulation resulted in a decreased level of cytosolic ATP, a higher mt membrane potential, an elevated amount of reactive oxygen species, and a reduced consumption of oxygen in the mitochondria. Interestingly, while TbAAC has previously been demonstrated to serve as the sole ADP/ATP carrier for ADP influx into the mitochondria, our data suggest that a second carrier for ATP influx may be present and active in the T. brucei mitochondrion. Overall, this study provides more insight into the delicate balance of the functional relationship between TbAAC and the oxidative phosphorylation (OXPHOS) pathway in an early diverged eukaryote.
- MeSH
- mitochondriální ADP/ATP-translokasy chemie genetika metabolismus MeSH
- molekulární evoluce * MeSH
- oxidativní fosforylace * MeSH
- protozoální proteiny chemie genetika metabolismus MeSH
- Trypanosoma brucei brucei genetika metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Complex I (NADH dehydrogenase) is the first enzyme in the respiratory chain. It catalyses the electron transfer from NADH to ubiquinone that is associated with proton pumping out of the matrix. In this study, we characterized NADH dehydrogenase activity in seven monoxenous trypanosomatid species: Blechomonas ayalai, Herpetomonas tarakana, Kentomonas sorsogonicus, Leptomonas seymouri, Novymonas esmeraldas, Sergeia podlipaevi and Wallacemonas raviniae. We also investigated the subunit composition of the complex I in dixenous Phytomonas serpens, in which its presence and activity have been previously documented. In addition to P. serpens, the complex I is functionally active in N. esmeraldas and S. podlipaevi. We also identified 24-32 subunits of the complex I in individual species by using mass spectrometry. Among them, for the first time, we recognized several proteins of the mitochondrial DNA origin.
The enzymes involved in Euglena oxidative phosphorylation (OXPHOS) were characterized in this study. We have demonstrated that Euglena gracilis strain Z and its stable bleached non-photosynthetic mutant strain WgmZOflL both possess fully functional OXPHOS apparatus as well as pathways requiring terminal alternative oxidase(s) and alternative mitochondrial NADH-dehydrogenase(s). Light (or dark) and plastid (non)functionality seem to have little effect on oxygen consumption, the activities of the enzymes involved in OXPHOS and the action of respiration inhibitors in Euglena. This study also demonstrates biochemical properties of complex III (cytochrome c reductase) in Euglena.
- MeSH
- elektronový transportní řetězec chemie metabolismus MeSH
- Euglena gracilis enzymologie genetika MeSH
- mitochondrie enzymologie MeSH
- mutace MeSH
- oxidativní fosforylace * MeSH
- protozoální proteiny chemie metabolismus MeSH
- spotřeba kyslíku MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Trypanosomatids are unicellular parasites living in a wide range of host environments, which to large extent shaped their mitochondrial energy metabolism, resulting in quite large differences even among closely related flagellates. In a comparative manner, we analyzed the activities and composition of mitochondrial respiratory complexes in four species (Leishmania tarentolae, Crithidia fasciculata, Phytomonas serpens and Trypanosoma brucei), which represent the main model trypanosomatids. Moreover, we measured the activity of mitochondrial glycerol-3-phosphate dehydrogenase, the overall oxygen consumption and the mitochondrial membrane potential in each species. The comparative analysis suggests an inverse relationship between the activities of respiratory complexes I and II, as well as the overall activity of the canonical complexes and glycerol-3-phosphate dehydrogenase. Our comparative analysis shows that mitochondrial functions are highly variable in these versatile parasites.
- MeSH
- glycerolfosfátdehydrogenasa metabolismus MeSH
- kyslík metabolismus MeSH
- membránový potenciál mitochondrií MeSH
- mitochondrie enzymologie metabolismus MeSH
- oxidativní fosforylace * MeSH
- transport elektronů MeSH
- Trypanosomatina genetika metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
