Transfer RNAs play a key role in protein synthesis. Following transcription, tRNAs are extensively processed prior to their departure from the nucleus to become fully functional during translation. This includes removal of 5′ leaders and 3′ trailers by a specific endo- and/or exonuclease, 3′ CCA tail addition, posttranscriptional modifications and in some cases intron removal. In this minireview, the critical factors of nuclear tRNA trafficking are described based on studies in classical models such as yeast and human cell lines. In addition, recent findings and identification of novel regulatory loops of nuclear tRNA trafficking in trypanosomes are discussed with emphasis on tRNA modifications. The comparison between the representatives of opisthokonts and excavates serves here to understand the evolutionary conservation and diversity of nuclear tRNA export mechanisms.
- MeSH
- buněčné linie MeSH
- lidé MeSH
- RNA jaderná genetika metabolismus MeSH
- RNA transferová genetika metabolismus MeSH
- Saccharomyces cerevisiae genetika metabolismus MeSH
- Trypanosoma genetika metabolismus MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
Trypanosoma brucei, a protist responsible for human African trypanosomiasis (sleeping sickness), is transmitted by the tsetse fly where the procyclic forms of the parasite develop in the proline-rich (1-2 mM) and glucose-depleted digestive tract. Proline is essential for the midgut colonization of the parasite in the insect vector, however other carbon sources could be available and used to feed its central metabolism. Here we show that procyclic trypanosomes can consume and metabolize metabolic intermediates, including those excreted from glucose catabolism (succinate, alanine and pyruvate), with the exception of acetate, which is the ultimate end-product excreted by the parasite. Among the tested metabolites, tricarboxylic acid (TCA) cycle intermediates (succinate, malate and α-ketoglutarate) stimulated growth of the parasite in the presence of 2 mM proline. The pathways used for their metabolism were mapped by proton-NMR metabolic profiling and phenotypic analyses of thirteen RNAi and/or null mutants affecting central carbon metabolism. We showed that (i) malate is converted to succinate by both the reducing and oxidative branches of the TCA cycle, which demonstrates that procyclic trypanosomes can use the full TCA cycle, (ii) the enormous rate of α-ketoglutarate consumption (15-times higher than glucose) is possible thanks to the balanced production and consumption of NADH at the substrate level and (iii) α-ketoglutarate is toxic for trypanosomes if not appropriately metabolized as observed for an α-ketoglutarate dehydrogenase null mutant. In addition, epimastigotes produced from procyclics upon overexpression of RBP6 showed a growth defect in the presence of 2 mM proline, which is rescued by α-ketoglutarate, suggesting that physiological amounts of proline are not sufficient per se for the development of trypanosomes in the fly. In conclusion, these data show that trypanosomes can metabolize multiple metabolites, in addition to proline, which allows them to confront challenging environments in the fly.
- MeSH
- citrátový cyklus účinky léků MeSH
- glukosa metabolismus MeSH
- hmyz - vektory parazitologie MeSH
- moucha tse-tse účinky léků parazitologie MeSH
- oxidace-redukce účinky léků MeSH
- prolin metabolismus farmakologie MeSH
- RNA interference fyziologie MeSH
- Trypanosoma brucei brucei účinky léků metabolismus MeSH
- Trypanosoma účinky léků metabolismus MeSH
- trypanozomóza africká farmakoterapie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Aquaglyceroporins (AQPs) are membrane proteins that function in osmoregulation and the uptake of low molecular weight solutes, in particular glycerol and urea. The AQP family is highly conserved, with two major subfamilies having arisen very early in prokaryote evolution and retained by eukaryotes. A complex evolutionary history indicates multiple lineage-specific expansions, losses and not uncommonly a complete loss. Consequently, the AQP family is highly evolvable and has been associated with significant events in life on Earth. In the African trypanosomes, a role for the AQP2 paralogue, in sensitivity to two chemotherapeutic agents, pentamidine and melarsoprol, is well established, albeit with the mechanisms for cell entry and resistance unclear until very recently. Here, we discuss AQP evolution, structure and mechanisms by which AQPs impact drug sensitivity, suggesting that AQP2 stability is highly sensitive to mutation while serving as the major uptake pathway for pentamidine.
Catalase is a widespread heme-containing enzyme, which converts hydrogen peroxide (H2 O2 ) to water and molecular oxygen, thereby protecting cells from the toxic effects of H2 O2 . Trypanosoma brucei is an aerobic protist, which conspicuously lacks this potent enzyme, present in virtually all organisms exposed to oxidative stress. To uncover the reasons for its absence in T. brucei, we overexpressed different catalases in procyclic and bloodstream stages of the parasite. The heterologous enzymes originated from the related insect-confined trypanosomatid Crithidia fasciculata and the human. While the trypanosomatid enzyme (cCAT) operates at low temperatures, its human homolog (hCAT) is adapted to the warm-blooded environment. Despite the presence of peroxisomal targeting signal in hCAT, both human and C. fasciculata catalases localized to the cytosol of T. brucei. Even though cCAT was efficiently expressed in both life cycle stages, the enzyme was active in the procyclic stage, increasing cell's resistance to the H2 O2 stress, yet its activity was suppressed in the cultured bloodstream stage. Surprisingly, following the expression of hCAT, the ability to establish the T. brucei infection in the tsetse fly midgut was compromised. In the mouse model, hCAT attenuated parasitemia and, consequently, increased the host's survival. Hence, we suggest that the activity of catalase in T. brucei is beneficial in vitro, yet it becomes detrimental for parasite's proliferation in both invertebrate and vertebrate hosts, leading to an inability to carry this, otherwise omnipresent, enzyme.
- MeSH
- hmyz účinky léků růst a vývoj metabolismus MeSH
- katalasa metabolismus MeSH
- peroxid vodíku farmakologie MeSH
- Trypanosoma brucei brucei účinky léků metabolismus MeSH
- Trypanosoma účinky léků metabolismus MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The mitochondrial contact site and cristae organization system (MICOS) mediates the formation of cristae, invaginations in the mitochondrial inner membrane. The highly diverged MICOS complex of the parasitic protist Trypanosoma brucei consists of nine subunits. Except for two Mic10-like and a Mic60-like protein, all subunits are specific for kinetoplastids. Here, we determined on a proteome-wide scale how ablation of individual MICOS subunits affects the levels of the other subunits. The results reveal co-regulation of TbMic10-1, TbMic10-2, TbMic16 and TbMic60, suggesting that these nonessential, integral inner membrane proteins form an interdependent network. Moreover, the ablation of TbMic34 and TbMic32 reveals another network consisting of the essential, intermembrane space-localized TbMic20, TbMic32, TbMic34 and TbMic40, all of which are peripherally associated with the inner membrane. The downregulation of TbMic20, TbMic32 and TbMic34 also interferes with mitochondrial protein import and reduces the size of the TbMic10-containing complexes. Thus, the diverged MICOS of trypanosomes contains two subcomplexes: a nonessential membrane-integrated one, organized around the conserved Mic10 and Mic60, that mediates cristae formation, and an essential membrane-peripheral one consisting of four kinetoplastid-specific subunits, that is required for import of intermembrane space proteins.
- MeSH
- membránové proteiny metabolismus MeSH
- mitochondriální membrány metabolismus MeSH
- mitochondriální proteiny metabolismus fyziologie MeSH
- mitochondrie metabolismus MeSH
- transport proteinů MeSH
- transportní proteiny mitochondriální membrány metabolismus MeSH
- Trypanosoma brucei brucei metabolismus fyziologie MeSH
- Trypanosoma metabolismus fyziologie MeSH
- vazba proteinů MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
MRP1/2 is a heteromeric protein complex that functions in the trypanosomatid mitochondrion as part of the RNA editing machinery, which facilitates multiple targeted insertions and deletions of uridines. MRP1/2 was shown to interact with MRB8170, which initiates RNA editing by marking pre-edited mRNAs, while TbRGG2 is required for its efficient progression on pan-edited mRNAs. Both MRP1/2 and TbRGG2 are capable of modulating RNA-RNA interactions in vitro. As determined by using iCLIP and RIP-qPCR, RNAs bound to MRP1/2 are characterized and compared with those associated with MRB8170 and TbRGG2. We provide evidence that MRP1 and MRB8170 have correlated binding and similar RNA crosslinking peak profiles over minimally and never-edited mRNAs. Our results suggest that MRP1 assists MRB8170 in RNA editing on minimally edited mRNAs.
- MeSH
- editace RNA MeSH
- messenger RNA genetika metabolismus MeSH
- mitochondrie genetika metabolismus MeSH
- proteiny vázající RNA metabolismus MeSH
- protozoální proteiny genetika metabolismus MeSH
- RNA mitochondriální genetika metabolismus MeSH
- Trypanosoma genetika metabolismus MeSH
- vazba proteinů MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The transition zone (TZ) of eukaryotic cilia and flagella is a structural intermediate between the basal body and the axoneme that regulates ciliary traffic. Mutations in genes encoding TZ proteins (TZPs) cause human inherited diseases (ciliopathies). Here, we use the trypanosome to identify TZ components and localize them to TZ subdomains, showing that the Bardet-Biedl syndrome complex (BBSome) is more distal in the TZ than the Meckel syndrome (MKS) complex. Several of the TZPs identified here have human orthologs. Functional analysis shows essential roles for TZPs in motility, in building the axoneme central pair apparatus and in flagellum biogenesis. Analysis using RNAi and HaloTag fusion protein approaches reveals that most TZPs (including the MKS ciliopathy complex) show long-term stable association with the TZ, whereas the BBSome is dynamic. We propose that some Bardet-Biedl syndrome and MKS pleiotropy may be caused by mutations that impact TZP complex dynamics.
- MeSH
- Bardetův-Biedlův syndrom genetika metabolismus MeSH
- bazální tělíska metabolismus ultrastruktura MeSH
- cilie genetika metabolismus MeSH
- ciliopatie genetika metabolismus MeSH
- cytoskelet metabolismus ultrastruktura MeSH
- encefalokéla genetika metabolismus MeSH
- flagella genetika metabolismus ultrastruktura MeSH
- fluorescenční mikroskopie MeSH
- kompartmentace buňky MeSH
- lidé MeSH
- mutace MeSH
- polycystická choroba ledvin genetika metabolismus MeSH
- poruchy ciliární motility genetika metabolismus MeSH
- proteom genetika metabolismus MeSH
- protozoální proteiny genetika metabolismus MeSH
- RNA interference MeSH
- transmisní elektronová mikroskopie MeSH
- Trypanosoma genetika metabolismus ultrastruktura MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The interactions of fish trypanosome culture forms with 11 purified lectins were compared using the agglutination test in microwell plates. Altogether, ten stocks of ten different freshwater fish species were examined. Three basic types of cell-lectin interactions were observed on the microscopical level. The strong agglutination of all stocks regardless their original host was found in the presence of Con A, PSA, RCA60, and RCA120, which implies the presence of relatively high amounts of sugar residues of D-mannose and D-galactose in the surface of culture forms of these parasites. Weak agglutinations of some stocks were observed in the presence of LCA, PNA, SBA, and WGA lectins, but their low intensity makes them not sufficiently reliable for stock characterization. The lectins UEA I, HPA, and PHA caused no agglutination. In conclusion, in case of unequivocal results no remarkable differences in the interactions of various stocks of trypanosomes culture forms with used lectins were observed. These results imply the high degree of similarity of their main cell surface saccharide structures.
- MeSH
- aglutinační testy MeSH
- lektiny metabolismus MeSH
- nemoci ryb parazitologie MeSH
- ryby MeSH
- sladká voda MeSH
- Trypanosoma metabolismus MeSH
- trypanozomiáza parazitologie veterinární MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
WHO technical report series ; no. 739
127 s. : il., tab. ; 20 cm
- MeSH
- epidemiologie organizace a řízení MeSH
- kontrola infekčních nemocí MeSH
- parazitologie MeSH
- socioekonomické faktory MeSH
- Trypanosoma izolace a purifikace klasifikace metabolismus patogenita růst a vývoj účinky léků MeSH
- trypanozomóza africká diagnóza farmakoterapie patofyziologie patologie MeSH
- Konspekt
- Patologie. Klinická medicína
- NLK Obory
- infekční lékařství
- NLK Publikační typ
- publikace WHO
