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1.
Invest Ophthalmol Vis Sci ; 62(12): 26, 2021 09 02.
Artigo em Inglês | MEDLINE | ID: mdl-34554178

RESUMO

Purpose: To characterize vitreous microparticles (MPs) in patients with traumatic proliferative vitreoretinopathy (PVR) and investigate their role in PVR pathogenesis. Methods: Vitreous MPs were characterized in patients with traumatic PVR, patients with rhegmatogenous retinal detachment (RRD) complicated with PVR, and control subjects by flow cytometry. The presence of M2 macrophages in epiretinal membranes was measured by immunostaining. Vitreous cytokines were quantified by ELISA assay. For in vitro studies, MPs isolated from THP-1 cell differentiated M1 and M2 macrophages, termed M1-MPs and M2-MPs, were used. The effects and mechanisms of M1-MPs and M2-MPs on RPE cell proliferation, migration, and epithelial to mesenchymal transition were analyzed. Results: Vitreous MPs derived from photoreceptors, microglia, and macrophages were significantly increased in patients with traumatic PVR in comparison with control and patients with RRD (PVR), whereas no significance was identified between the two control groups. M2 macrophages were present in epiretinal membranes, and their signature cytokines were markedly elevated in the vitreous of patients with traumatic PVR. Moreover, MPs from M2 macrophages were increased in the vitreous of patients with traumatic PVR. In vitro analyses showed that M2-MPs promoted the proliferation and migration of RPE cells via activation of the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling pathway. However, M2-MPs did not induce the expression of fibrotic proteins, including fibronectin, α-smooth muscle actin, and N-cadherin in RPE cells. Conclusions: This study demonstrated increased MP shedding in the vitreous of patients with traumatic PVR; specifically, MPs derived from M2 polarized macrophages may contribute to PVR progression by stimulating RPE cell proliferation and migration.


Assuntos
Movimento Celular/fisiologia , Proliferação de Células/fisiologia , Ferimentos Oculares Penetrantes/metabolismo , Macrófagos/metabolismo , Epitélio Pigmentado da Retina/citologia , Vitreorretinopatia Proliferativa/metabolismo , Corpo Vítreo/citologia , Adulto , Idoso , Western Blotting , Células Cultivadas , Citocinas/metabolismo , Ensaio de Imunoadsorção Enzimática , Membrana Epirretiniana/metabolismo , Feminino , Citometria de Fluxo , Humanos , Masculino , Microcorpos/metabolismo , Microscopia de Fluorescência , Pessoa de Meia-Idade , Fosfatidilinositol 3-Quinase/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , Descolamento Retiniano/metabolismo , Transdução de Sinais , Serina-Treonina Quinases TOR/metabolismo
2.
PLoS Biol ; 19(8): e3001359, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34388147

RESUMO

Microorganisms must make the right choice for nutrient consumption to adapt to their changing environment. As a consequence, bacteria and yeasts have developed regulatory mechanisms involving nutrient sensing and signaling, known as "catabolite repression," allowing redirection of cell metabolism to maximize the consumption of an energy-efficient carbon source. Here, we report a new mechanism named "metabolic contest" for regulating the use of carbon sources without nutrient sensing and signaling. Trypanosoma brucei is a unicellular eukaryote transmitted by tsetse flies and causing human African trypanosomiasis, or sleeping sickness. We showed that, in contrast to most microorganisms, the insect stages of this parasite developed a preference for glycerol over glucose, with glucose consumption beginning after the depletion of glycerol present in the medium. This "metabolic contest" depends on the combination of 3 conditions: (i) the sequestration of both metabolic pathways in the same subcellular compartment, here in the peroxisomal-related organelles named glycosomes; (ii) the competition for the same substrate, here ATP, with the first enzymatic step of the glycerol and glucose metabolic pathways both being ATP-dependent (glycerol kinase and hexokinase, respectively); and (iii) an unbalanced activity between the competing enzymes, here the glycerol kinase activity being approximately 80-fold higher than the hexokinase activity. As predicted by our model, an approximately 50-fold down-regulation of the GK expression abolished the preference for glycerol over glucose, with glucose and glycerol being metabolized concomitantly. In theory, a metabolic contest could be found in any organism provided that the 3 conditions listed above are met.


Assuntos
Glicerol Quinase/metabolismo , Glicerol/metabolismo , Hexoquinase/metabolismo , Microcorpos/enzimologia , Trypanosoma brucei brucei/metabolismo , Trifosfato de Adenosina/metabolismo , Linhagem Celular
3.
mBio ; 12(3): e0037521, 2021 06 29.
Artigo em Inglês | MEDLINE | ID: mdl-34044588

RESUMO

Glycosomes are peroxisome-related organelles of trypanosomatid parasites containing metabolic pathways, such as glycolysis and biosynthesis of sugar nucleotides, usually present in the cytosol of other eukaryotes. UDP-glucose pyrophosphorylase (UGP), the enzyme responsible for the synthesis of the sugar nucleotide UDP-glucose, is localized in the cytosol and glycosomes of the bloodstream and procyclic trypanosomes, despite the absence of any known peroxisome-targeting signal (PTS1 and PTS2). The questions that we address here are (i) is the unusual glycosomal biosynthetic pathway of sugar nucleotides functional and (ii) how is the PTS-free UGP imported into glycosomes? We showed that UGP is imported into glycosomes by piggybacking on the glycosomal PTS1-containing phosphoenolpyruvate carboxykinase (PEPCK) and identified the domains involved in the UGP/PEPCK interaction. Proximity ligation assays revealed that this interaction occurs in 3 to 10% of glycosomes, suggesting that these correspond to organelles competent for protein import. We also showed that UGP is essential for the growth of trypanosomes and that both the glycosomal and cytosolic metabolic pathways involving UGP are functional, since the lethality of the knockdown UGP mutant cell line (RNAiUGP, where RNAi indicates RNA interference) was rescued by expressing a recoded UGP (rUGP) in the organelle (RNAiUGP/EXPrUGP-GPDH, where GPDH is glycerol-3-phosphate dehydrogenase). Our conclusion was supported by targeted metabolomic analyses (ion chromatography-high-resolution mass spectrometry [IC-HRMS]) showing that UDP-glucose is no longer detectable in the RNAiUGP mutant, while it is still produced in cells expressing UGP exclusively in the cytosol (PEPCK null mutant) or glycosomes (RNAiUGP/EXPrUGP-GPDH). Trypanosomatids are the only known organisms to have selected functional peroxisomal (glycosomal) sugar nucleotide biosynthetic pathways in addition to the canonical cytosolic ones. IMPORTANCE Unusual compartmentalization of metabolic pathways within organelles is one of the most enigmatic features of trypanosomatids. These unicellular eukaryotes are the only organisms that sequestered glycolysis inside peroxisomes (glycosomes), although the selective advantage of this compartmentalization is still not clear. Trypanosomatids are also unique for the glycosomal localization of enzymes of the sugar nucleotide biosynthetic pathways, which are also present in the cytosol. Here, we showed that the cytosolic and glycosomal pathways are functional. As in all other eukaryotes, the cytosolic pathways feed glycosylation reactions; however, the role of the duplicated glycosomal pathways is currently unknown. We also showed that one of these enzymes (UGP) is imported into glycosomes by piggybacking on another glycosomal enzyme (PEPCK); they are not functionally related. The UGP/PEPCK association is unique since all piggybacking examples reported to date involve functionally related interacting partners, which broadens the possible combinations of carrier-cargo proteins being imported as hetero-oligomers.


Assuntos
Microcorpos/metabolismo , Nucleotídeos/metabolismo , Açúcares/metabolismo , Trypanosoma brucei brucei/enzimologia , Trypanosoma brucei brucei/metabolismo , UTP-Glucose-1-Fosfato Uridililtransferase/metabolismo , Citosol/metabolismo , Redes e Vias Metabólicas , Nucleotídeos/biossíntese , Transporte Proteico , Trypanosoma brucei brucei/genética , UTP-Glucose-1-Fosfato Uridililtransferase/genética
4.
J Biol Chem ; 296: 100548, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33741344

RESUMO

The genome of trypanosomatids rearranges by using repeated sequences as platforms for amplification or deletion of genomic segments. These stochastic recombination events have a direct impact on gene dosage and foster the selection of adaptive traits in response to environmental pressure. We provide here such an example by showing that the phosphoenolpyruvate carboxykinase (PEPCK) gene knockout (Δpepck) leads to the selection of a deletion event between two tandemly arranged fumarate reductase (FRDg and FRDm2) genes to produce a chimeric FRDg-m2 gene in the Δpepck∗ cell line. FRDg is expressed in peroxisome-related organelles, named glycosomes, expression of FRDm2 has not been detected to date, and FRDg-m2 is nonfunctional and cytosolic. Re-expression of FRDg significantly impaired growth of the Δpepck∗ cells, but FRD enzyme activity was not required for this negative effect. Instead, glycosomal localization as well as the covalent flavinylation motif of FRD is required to confer growth retardation and intracellular accumulation of reactive oxygen species (ROS). The data suggest that FRDg, similar to Escherichia coli FRD, can generate ROS in a flavin-dependent process by transfer of electrons from NADH to molecular oxygen instead of fumarate when the latter is unavailable, as in the Δpepck background. Hence, growth retardation is interpreted as a consequence of increased production of ROS, and rearrangement of the FRD locus liberates Δpepck∗ cells from this obstacle. Interestingly, intracellular production of ROS has been shown to be required to complete the parasitic cycle in the insect vector, suggesting that FRDg may play a role in this process.


Assuntos
Glucose/metabolismo , Recombinação Homóloga , Microcorpos/enzimologia , Espécies Reativas de Oxigênio/metabolismo , Succinato Desidrogenase/metabolismo , Trypanosoma brucei brucei/metabolismo , Células Cultivadas , Flavinas/metabolismo , Succinato Desidrogenase/genética , Trypanosoma brucei brucei/genética , Trypanosoma brucei brucei/crescimento & desenvolvimento
5.
PLoS Negl Trop Dis ; 15(2): e0009132, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33592041

RESUMO

In Trypanosoma brucei, there are fourteen enzymatic biotransformations that collectively convert glucose into five essential nucleotide sugars: UDP-Glc, UDP-Gal, UDP-GlcNAc, GDP-Man and GDP-Fuc. These biotransformations are catalyzed by thirteen discrete enzymes, five of which possess putative peroxisome targeting sequences. Published experimental analyses using immunofluorescence microscopy and/or digitonin latency and/or subcellular fractionation and/or organelle proteomics have localized eight and six of these enzymes to the glycosomes of bloodstream form and procyclic form T. brucei, respectively. Here we increase these glycosome localizations to eleven in both lifecycle stages while noting that one, phospho-N-acetylglucosamine mutase, also localizes to the cytoplasm. In the course of these studies, the heterogeneity of glycosome contents was also noted. These data suggest that, unlike other eukaryotes, all of nucleotide sugar biosynthesis in T. brucei is compartmentalized to the glycosomes in both lifecycle stages. The implications are discussed.


Assuntos
Microcorpos/metabolismo , Nucleotídeos/biossíntese , Açúcares/metabolismo , Trypanosoma brucei brucei/metabolismo , Estágios do Ciclo de Vida/fisiologia , Microcorpos/enzimologia , Trypanosoma brucei brucei/enzimologia
6.
Parasitol Res ; 120(4): 1421-1428, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33098461

RESUMO

Trypanosoma cruzi, the causative agent of Chagas' disease, belongs to the Trypanosomatidae family. The parasite undergoes multiple morphological and metabolic changes during its life cycle, in which it can use both glucose and amino acids as carbon and energy sources. The glycolytic pathway is peculiar in that its first six or seven steps are compartmentalized in glycosomes, and has a two-branched auxiliary glycosomal system functioning beyond the intermediate phosphoenolpyruvate (PEP) that is also used in the cytosol as substrate by pyruvate kinase. The pyruvate phosphate dikinase (PPDK) is the first enzyme of one branch, converting PEP, PPi, and AMP into pyruvate, Pi, and ATP. Here we present a kinetic study of PPDK from T. cruzi that reveals its hysteretic behavior. The length of the lag phase, and therefore the time for reaching higher specific activity values is affected by the concentration of the enzyme, the presence of hydrogen ions and the concentrations of the enzyme's substrates. Additionally, the formation of a more active PPDK with more complex structure is promoted by it substrates and the cation ammonium, indicating that this enzyme equilibrates between the monomeric (less active) and a more complex (more active) form depending on the medium. These results confirm the hysteretic behavior of PPDK and are suggestive for its functioning as a regulatory mechanism of this auxiliary pathway. Such a regulation could serve to distribute the glycolytic flux over the two auxiliary branches as a response to the different environments that the parasite encounters during its life cycle.


Assuntos
Doença de Chagas/parasitologia , Piruvato Ortofosfato Diquinase/metabolismo , Trypanosoma cruzi/enzimologia , Monofosfato de Adenosina/metabolismo , Difosfatos/metabolismo , Glucose/metabolismo , Glicólise , Concentração de Íons de Hidrogênio , Cinética , Microcorpos/enzimologia , Fosfoenolpiruvato/metabolismo , Piruvato Ortofosfato Diquinase/química , Piruvatos/metabolismo , Proteínas Recombinantes/metabolismo
7.
Cell Rep ; 33(12): 108528, 2020 12 22.
Artigo em Inglês | MEDLINE | ID: mdl-33326798

RESUMO

Soluble forms of angiotensin-converting enzyme 2 (ACE2) have recently been shown to inhibit severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. We report on an improved soluble ACE2, termed a "microbody," in which the ACE2 ectodomain is fused to Fc domain 3 of the immunoglobulin (Ig) heavy chain. The protein is smaller than previously described ACE2-Ig Fc fusion proteins and contains an H345A mutation in the ACE2 catalytic active site that inactivates the enzyme without reducing its affinity for the SARS-CoV-2 spike. The disulfide-bonded ACE2 microbody protein inhibits entry of SARS-CoV-2 spike protein pseudotyped virus and replication of live SARS-CoV-2 in vitro and in a mouse model. Its potency is 10-fold higher than soluble ACE2, and it can act after virus bound to the cell. The microbody inhibits the entry of ß coronaviruses and virus with the variant D614G spike. The ACE2 microbody may be a valuable therapeutic for coronavirus disease 2019 (COVID-19) that is active against viral variants and future coronaviruses.


Assuntos
Enzima de Conversão de Angiotensina 2/metabolismo , Antivirais/farmacologia , Fragmentos Fc das Imunoglobulinas/metabolismo , Microcorpos/metabolismo , SARS-CoV-2/efeitos dos fármacos , Sequência de Aminoácidos , Animais , COVID-19/prevenção & controle , COVID-19/virologia , Modelos Animais de Doenças , Dissulfetos/metabolismo , Feminino , Células HEK293 , Humanos , Masculino , Camundongos Transgênicos , Domínios Proteicos , Multimerização Proteica , SARS-CoV-2/patogenicidade , Glicoproteína da Espícula de Coronavírus/química , Glicoproteína da Espícula de Coronavírus/metabolismo , Vírion/metabolismo , Internalização do Vírus/efeitos dos fármacos
8.
Parasitology ; 147(14): 1801-1809, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-32981530

RESUMO

Trypanosomes are blood-borne parasites that can infect a variety of different vertebrates, including animals and humans. This study aims to broaden scientific knowledge about the presence and biodiversity of trypanosomes in Australian bats. Molecular and morphological analysis was performed on 86 blood samples collected from seven different species of microbats in Western Australia. Phylogenetic analysis on 18S rDNA and glycosomal glyceraldehyde phosphate dehydrogenase (gGAPDH) sequences identified Trypanosoma dionisii in five different Australian native species of microbats; Chalinolobus gouldii, Chalinolobus morio, Nyctophilus geoffroyi, Nyctophilus major and Scotorepens balstoni. In addition, two novels, genetically distinct T. dionisii genotypes were detected and named T. dionisii genotype Aus 1 and T. dionisii genotype Aus 2. Genotype Aus 2 was the most prevalent and infected 20.9% (18/86) of bats in the present study, while genotype Aus 1 was less prevalent and was identified in 5.8% (5/86) of Australian bats. Morphological analysis was conducted on trypomastigotes identified in blood films, with morphological parameters consistent with trypanosome species in the subgenus Schizotrypanum. This is the first report of T. dionisii in Australia and in Australian native bats, which further contributes to the global distribution of this cosmopolitan bat trypanosome.


Assuntos
Quirópteros , Trypanosoma/isolamento & purificação , Tripanossomíase/veterinária , Animais , Gliceraldeído-3-Fosfato Desidrogenases/análise , Microcorpos/química , Prevalência , Proteínas de Protozoários/análise , RNA de Protozoário/análise , RNA Ribossômico 18S/análise , Trypanosoma/enzimologia , Trypanosoma/genética , Tripanossomíase/epidemiologia , Austrália Ocidental/epidemiologia
9.
J Biol Chem ; 295(24): 8331-8347, 2020 06 12.
Artigo em Inglês | MEDLINE | ID: mdl-32354742

RESUMO

Introduced about a century ago, suramin remains a frontline drug for the management of early-stage East African trypanosomiasis (sleeping sickness). Cellular entry into the causative agent, the protozoan parasite Trypanosoma brucei, occurs through receptor-mediated endocytosis involving the parasite's invariant surface glycoprotein 75 (ISG75), followed by transport into the cytosol via a lysosomal transporter. The molecular basis of the trypanocidal activity of suramin remains unclear, but some evidence suggests broad, but specific, impacts on trypanosome metabolism (i.e. polypharmacology). Here we observed that suramin is rapidly accumulated in trypanosome cells proportionally to ISG75 abundance. Although we found little evidence that suramin disrupts glycolytic or glycosomal pathways, we noted increased mitochondrial ATP production, but a net decrease in cellular ATP levels. Metabolomics highlighted additional impacts on mitochondrial metabolism, including partial Krebs' cycle activation and significant accumulation of pyruvate, corroborated by increased expression of mitochondrial enzymes and transporters. Significantly, the vast majority of suramin-induced proteins were normally more abundant in the insect forms compared with the blood stage of the parasite, including several proteins associated with differentiation. We conclude that suramin has multiple and complex effects on trypanosomes, but unexpectedly partially activates mitochondrial ATP-generating activity. We propose that despite apparent compensatory mechanisms in drug-challenged cells, the suramin-induced collapse of cellular ATP ultimately leads to trypanosome cell death.


Assuntos
Metabolismo Energético/efeitos dos fármacos , Mitocôndrias/metabolismo , Suramina/farmacologia , Trypanosoma brucei brucei/metabolismo , Trifosfato de Adenosina/metabolismo , Flagelos/efeitos dos fármacos , Flagelos/metabolismo , Flagelos/ultraestrutura , Glicólise/efeitos dos fármacos , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Metaboloma/efeitos dos fármacos , Microcorpos/efeitos dos fármacos , Microcorpos/metabolismo , Microcorpos/ultraestrutura , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/ultraestrutura , Modelos Moleculares , Prolina/metabolismo , Proteoma/metabolismo , ATPases Translocadoras de Prótons/metabolismo , Proteínas de Protozoários/metabolismo , Ácido Pirúvico/metabolismo
10.
Biochem J ; 477(9): 1733-1744, 2020 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-32329788

RESUMO

Post-translational modifications provide suitable mechanisms for cellular adaptation to environmental changes. Lysine acetylation is one of these modifications and occurs with the addition of an acetyl group to Nε-amino chain of this residue, eliminating its positive charge. Recently, we found distinct acetylation profiles of procyclic and bloodstream forms of Trypanosoma brucei, the agent of African Trypanosomiasis. Interestingly, glycolytic enzymes were more acetylated in the procyclic, which develops in insects and uses oxidative phosphorylation to obtain energy, compared with the bloodstream form, whose main source of energy is glycolysis. Here, we investigated whether acetylation regulates the T. brucei fructose 1,6-bisphosphate aldolase. We found that aldolase activity was reduced in procyclic parasites cultivated in the absence of glucose and partial recovered by in vitro deacetylation. Similarly, acetylation of protein extracts from procyclics cultivated in glucose-rich medium, caused a reduction in the aldolase activity. In addition, aldolase acetylation levels were higher in procyclics cultivated in the absence of glucose compared with those cultivated in the presence of glucose. To further confirm the role of acetylation, lysine residues near the catalytic site were substituted by glutamine in recombinant T. brucei aldolase. These replacements, especially K157, inhibited enzymatic activity, changed the electrostatic surface potential, decrease substrate binding and modify the catalytic pocket structure of the enzyme, as predicted by in silico analysis. Taken together, these data confirm the role of acetylation in regulating the activity of an enzyme from the glycolytic pathway of T. brucei, expanding the factors responsible for regulating important pathways in this parasite.


Assuntos
Frutose-Bifosfato Aldolase/metabolismo , Glicólise/fisiologia , Lisina/metabolismo , Trypanosoma brucei brucei/metabolismo , Acetilação , Animais , Microcorpos/metabolismo , Processamento de Proteína Pós-Traducional , Proteínas de Protozoários/metabolismo
11.
Methods Mol Biol ; 2116: 627-643, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32221946

RESUMO

Glycosomes are peroxisome-related organelles of trypanosomatids in which the glycolytic and some other metabolic pathways are compartmentalized. We describe here two methods for the purification of glycosomes from Trypanosoma cruzi for preparative purposes, differential and isopycnic centrifugation. These are two techniques that allow the separation of different cellular compartments based on their different physicochemical characteristics. The first type of centrifugation is a rapid method that does not require large inputs and allows for fractions enriched in specific cell compartments to be obtained. The second type of centrifugation is a more elaborate method, but enables highly purified cellular compartments to be isolated. The success in obtaining these purified, intact organelles critically depends on using an appropriate method for controlled rupture of the cells.


Assuntos
Fracionamento Celular/métodos , Microcorpos , Trypanosoma cruzi/citologia , Centrifugação Isopícnica/instrumentação , Centrifugação Isopícnica/métodos
12.
Methods Mol Biol ; 2116: 425-447, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32221935

RESUMO

In this chapter we describe different electron microscopy techniques such as freeze fracture, deep etching, and three-dimensional reconstruction, obtained by electron tomography or focused ion beam scanning electron microscopy (FIB-SEM), combined with quick-freezing methods in order to reveal aspects of the cell structure in trypanosomatids. For this purpose, we chose protists that evolve in a mutualistic way with a symbiotic bacterium. Such cells represent excellent models to study the positioning and distribution of organelles, since the symbiotic bacterium interacts with different organelles of the host trypanosomatid. We demonstrate that the employment of such techniques can show the proximity and even the interaction of the symbiotic bacterium with different structures of the protist host, such as the nucleus and the glycosomes. In addition, the quick-freezing approach can reveal new aspects of the gram-negative bacterial envelope, such as the presence of a greatly reduced cell wall between the two membrane units.


Assuntos
Bactérias/citologia , Microscopia Eletrônica de Varredura/métodos , Trypanosomatina/microbiologia , Núcleo Celular/microbiologia , Parede Celular , Microcorpos/microbiologia , Microscopia Eletrônica de Varredura/instrumentação , Simbiose , Trypanosomatina/citologia
13.
Artigo em Inglês | MEDLINE | ID: mdl-32083023

RESUMO

Glycosomes are peroxisome-related organelles that have been identified in kinetoplastids and diplonemids. The hallmark of glycosomes is their harboring of the majority of the glycolytic enzymes. Our biochemical studies and proteome analysis of Trypanosoma cruzi glycosomes have located, in addition to enzymes of the glycolytic pathway, enzymes of several other metabolic processes in the organelles. These analyses revealed many aspects in common with glycosomes from other trypanosomatids as well as features that seem specific for T. cruzi. Their enzyme content indicates that T. cruzi glycosomes are multifunctional organelles, involved in both several catabolic processes such as glycolysis and anabolic ones. Specifically discussed in this minireview are the cross-talk between glycosomal metabolism and metabolic processes occurring in other cell compartments, and the importance of metabolite translocation systems in the glycosomal membrane to enable the coordination between the spatially separated processes. Possible mechanisms for metabolite translocation across the membrane are suggested by proteins identified in the organelle's membrane-homologs of the ABC and MCF transporter families-and the presence of channels as inferred previously from the detection of channel-forming proteins in glycosomal membrane preparations from the related parasite T. brucei. Together, these data provide insight in the way in which different parts of T. cruzi metabolism, although uniquely distributed over different compartments, are integrated and regulated. Moreover, this information reveals opportunities for the development of drugs against Chagas disease caused by these parasites and for which currently no adequate treatment is available.


Assuntos
Doença de Chagas , Trypanosoma brucei brucei , Trypanosoma cruzi , Doença de Chagas/metabolismo , Glicólise , Humanos , Microcorpos , Organelas
14.
mSphere ; 5(1)2020 02 19.
Artigo em Inglês | MEDLINE | ID: mdl-32075879

RESUMO

Kinetoplastid parasites, including Trypanosoma brucei, Trypanosoma cruzi, and Leishmania, harbor unique organelles known as glycosomes, which are evolutionarily related to peroxisomes. Glycosome/peroxisome biogenesis is mediated by proteins called peroxins that facilitate organelle formation, proliferation, and degradation and import of proteins housed therein. Import of matrix proteins occurs via one of two pathways that are dictated by their peroxisome targeting sequence (PTS). In PTS1 import, a C-terminal tripeptide sequence, most commonly SKL, is recognized by the soluble receptor Pex5. In PTS2 import, a less conserved N-terminal sequence is recognized by Pex7. The soluble receptors deliver their cargo to the import channel consisting minimally of Pex13 and Pex14. While much of the import process is conserved, kinetoplastids are the only organisms to have two Pex13s, Pex13.1 and Pex13.2. It is unclear why trypanosomes require two Pex13s when one is sufficient for most eukaryotes. To interrogate the role of Pex13.2, we have employed biochemical approaches to partially resolve the composition of the Pex13/Pex14 import complexes in T. brucei and characterized glycosome morphology and protein import in Pex13.2-deficient parasites. Here, we show that Pex13.2 is an integral glycosome membrane protein that interacts with Pex13.1 and Pex14. The N terminus of Pex13.2 faces the cytoplasmic side of the membrane, where it can facilitate interactions required for protein import. Two-dimensional gel electrophoresis revealed three glycosome membrane complexes containing combinations of Pex13.1, Pex13.2, and Pex14. The silencing of Pex13.2 resulted in parasites with fewer, larger glycosomes and disrupted glycosome protein import, suggesting the protein is involved in glycosome biogenesis as well as protein import. Furthermore, superresolution microscopy demonstrated that Pex13.2 localizes to discrete foci in the glycosome periphery, indicating that the glycosome periphery is not homogenous.IMPORTANCE Trypanosoma brucei causes human African trypanosomiasis and a wasting disease called Nagana in livestock. Current treatments are expensive, toxic, and difficult to administer. Because of this, the search for new drug targets is essential. T. brucei has glycosomes that are essential to parasite survival; however, our ability to target them in drug development is hindered by our lack of understanding about how these organelles are formed and maintained. This work forwards our understanding of how the parasite-specific protein Pex13.2 functions in glycosome protein import and lays the foundation for future studies focused on blocking Pex13.2 function, which would be lethal to bloodstream-form parasites that reside in the mammalian bloodstream.


Assuntos
Microcorpos/metabolismo , Peroxinas/metabolismo , Peroxissomos/metabolismo , Proteínas de Protozoários/metabolismo , Trypanosoma brucei brucei/genética , Citosol/química , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Peroxinas/genética , Peroxissomos/genética , Transporte Proteico , Proteínas de Protozoários/genética
15.
PLoS Negl Trop Dis ; 14(1): e0007945, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31895927

RESUMO

Chagas disease, also known as American trypanosomiasis, is a potentially life-threatening illness caused by the protozoan parasite, Trypanosoma cruzi, and is transmitted by triatomine insects during its blood meal. Proliferative epimastigotes forms thrive inside the insects in the presence of heme (iron protoporphyrin IX), an abundant product of blood digestion, however little is known about the metabolic outcome of this signaling molecule in the parasite. Trypanosomatids exhibit unusual gene transcription employing a polycistronic transcription mechanism through trans-splicing that regulates its life cycle. Using the Deep Seq transcriptome sequencing we characterized the heme induced transcriptome of epimastigotes and determined that most of the upregulated genes were related to glucose metabolism inside the glycosomes. These results were supported by the upregulation of glycosomal isoforms of PEPCK and fumarate reductase of heme-treated parasites, implying that the fermentation process was favored. Moreover, the downregulation of mitochondrial gene enzymes in the presence of heme also supported the hypothesis that heme shifts the parasite glycosomal glucose metabolism towards aerobic fermentation. These results are examples of the environmental metabolic plasticity inside the vector supporting ATP production, promoting epimastigotes proliferation and survival.


Assuntos
Perfilação da Expressão Gênica , Heme/farmacologia , Trypanosoma cruzi/efeitos dos fármacos , Trypanosoma cruzi/metabolismo , Animais , Doença de Chagas/metabolismo , Genes Mitocondriais , Glucose/metabolismo , Insetos Vetores/parasitologia , Microcorpos/metabolismo , Transdução de Sinais , Transcrição Genética , Triatominae/parasitologia , Trypanosoma cruzi/genética , Trypanosoma cruzi/crescimento & desenvolvimento
16.
Acta Trop ; 201: 105217, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31605692

RESUMO

Glycosomes of trypanosomatids are peroxisome-like organelles comprising unique metabolic features, among which the lack of the hallmark peroxisomal enzyme catalase. The absence of this highly efficient peroxidase from glycosomes is presumably compensated by other antioxidants, peroxidases of the peroxiredoxin (PRX) family being the most promising candidates for this function. Here, we follow on this premise and investigate the product of a Leishmania infantum gene coding for a putative glycosomal PRX (LigPRX). First, we demonstrate that LigPRX localizes to glycosomes, resorting to indirect immunofluorescence analysis. Second, we prove that purified recombinant LigPRX is an active peroxidase in vitro. Third, we generate viable LigPRX-depleted L. infantum promastigotes by classical homologous recombination. Surprisingly, phenotypic analysis of these knockout parasites revealed that promastigote survival, replication, and protection from oxidative and nitrosative insults can proceed normally in the absence of LigPRX. Noticeably, we also witness that LigPRX-depleted parasites can infect and thrive in mice to the same extent as wild type parasites. Overall, by disclosing the dispensable character of the glycosomal peroxiredoxin in L. infantum, this work excludes this enzyme from being a key component of the glycosomal hydroperoxide metabolism and contemplates alternative players for this function.


Assuntos
Leishmania infantum/genética , Leishmania infantum/metabolismo , Microcorpos/metabolismo , Oxirredutases/metabolismo , Peroxirredoxinas/metabolismo , Proteínas de Protozoários/genética , Proteínas de Protozoários/metabolismo , Animais , Camundongos , Microcorpos/genética , Oxirredutases/genética , Peroxirredoxinas/genética
17.
Biochim Biophys Acta Mol Cell Res ; 1866(12): 118520, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31369765

RESUMO

Trypanosomatid parasites cause devastating African sleeping sickness, Chagas disease, and Leishmaniasis that affect about 18 million people worldwide. Recently, we showed that the biogenesis of glycosomes could be the "Achilles' heel" of trypanosomatids suitable for the development of new therapies against trypanosomiases. This was shown for inhibitors of the import machinery of matrix proteins, while the distinct machinery for the topogenesis of glycosomal membrane proteins evaded investigation due to the lack of a druggable interface. Here we report on the identification of the highly divergent trypanosomal PEX3, a central component of the transport machinery of peroxisomal membrane proteins and the master regulator of peroxisome biogenesis. The trypanosomatid PEX3 shows very low degree of conservation and its identification was made possible by a combinatory approach identifying of PEX19-interacting proteins and secondary structure homology screening. The trypanosomal PEX3 localizes to glycosomes and directly interacts with the membrane protein import receptor PEX19. RNAi-studies revealed that the PEX3 is essential and that its depletion results in mislocalization of glycosomal proteins to the cytosol and a severe growth defect. Comparison of the parasites and human PEX3-PEX19 interface disclosed differences that might be accessible for drug development. The absolute requirement for biogenesis of glycosomes and its structural distinction from its human counterpart make PEX3 a prime drug target for the development of novel therapies against trypanosomiases. The identification paves the way for future drug development targeting PEX3, and for the analysis of additional partners involved in this crucial step of glycosome biogenesis.


Assuntos
Microcorpos/metabolismo , Proteínas de Protozoários/metabolismo , Trypanosomatina/metabolismo , Proteínas de Arabidopsis/metabolismo , Células Cultivadas , Biologia Computacional , Humanos , Lipoproteínas/metabolismo , Proteínas de Membrana/metabolismo , Peroxinas/metabolismo , Trypanosomatina/citologia
18.
mBio ; 10(4)2019 07 09.
Artigo em Inglês | MEDLINE | ID: mdl-31289175

RESUMO

Glycosomes are peroxisome-related organelles that compartmentalize the glycolytic enzymes in kinetoplastid parasites. These organelles are developmentally regulated in their number and composition, allowing metabolic adaptation to the parasite's needs in the blood of mammalian hosts or within their arthropod vector. A protein phosphatase cascade regulates differentiation between parasite developmental forms, comprising a tyrosine phosphatase, Trypanosoma brucei PTP1 (TbPTP1), which dephosphorylates and inhibits a serine threonine phosphatase, TbPIP39, which promotes differentiation. When TbPTP1 is inactivated, TbPIP39 is activated and during differentiation becomes located in glycosomes. Here we have tracked TbPIP39 recruitment to glycosomes during differentiation from bloodstream "stumpy" forms to procyclic forms. Detailed microscopy and live-cell imaging during the synchronous transition between life cycle stages revealed that in stumpy forms, TbPIP39 is located at a periflagellar pocket site closely associated with TbVAP, which defines the flagellar pocket endoplasmic reticulum. TbPTP1 is also located at the same site in stumpy forms, as is REG9.1, a regulator of stumpy-enriched mRNAs. This site provides a molecular node for the interaction between TbPTP1 and TbPIP39. Within 30 min of the initiation of differentiation, TbPIP39 relocates to glycosomes, whereas TbPTP1 disperses to the cytosol. Overall, the study identifies a "stumpy regulatory nexus" (STuRN) that coordinates the molecular components of life cycle signaling and glycosomal development during transmission of Trypanosoma brucei IMPORTANCE African trypanosomes are parasites of sub-Saharan Africa responsible for both human and animal disease. The parasites are transmitted by tsetse flies, and completion of their life cycle involves progression through several development steps. The initiation of differentiation between blood and tsetse fly forms is signaled by a phosphatase cascade, ultimately trafficked into peroxisome-related organelles called glycosomes that are unique to this group of organisms. Glycosomes undergo substantial remodeling of their composition and function during the differentiation step, but how this is regulated is not understood. Here we identify a cytological site where the signaling molecules controlling differentiation converge before the dispersal of one of them into glycosomes. In combination, the study provides the first insight into the spatial coordination of signaling pathway components in trypanosomes as they undergo cell-type differentiation.


Assuntos
Microcorpos/metabolismo , Fosfoproteínas Fosfatases/metabolismo , Proteínas Tirosina Fosfatases/metabolismo , Proteínas de Protozoários/metabolismo , Trypanosoma brucei brucei/genética , Trypanosoma brucei brucei/fisiologia , Estágios do Ciclo de Vida , Imagem Óptica , Transdução de Sinais , Trypanosoma brucei brucei/enzimologia
19.
Life Sci Alliance ; 2(4)2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31341002

RESUMO

Trypanosomatid parasites are infectious agents for diseases such as African sleeping sickness, Chagas disease, and leishmaniasis that threaten millions of people, mostly in the emerging world. Trypanosomes compartmentalize glycolytic enzymes to an organelle called the glycosome, a specialized peroxisome. Functionally intact glycosomes are essential for trypanosomatid viability, making glycosomal proteins as potential drug targets against trypanosomatid diseases. Peroxins (Pex), of which Pex3 is the master regulator, control glycosome biogenesis. Although Pex3 has been found throughout the eukaryota, its identity has remained stubbornly elusive in trypanosomes. We used bioinformatics predictive of protein secondary structure to identify trypanosomal Pex3. Microscopic and biochemical analyses showed trypanosomal Pex3 to be glycosomal. Interaction of Pex3 with the peroxisomal membrane protein receptor Pex19 observed for other eukaryotes is replicated by trypanosomal Pex3 and Pex19. Depletion of Pex3 leads to mislocalization of glycosomal proteins to the cytosol, reduced glycosome numbers, and trypanosomatid death. Our findings are consistent with Pex3 being an essential gene in trypanosomes.


Assuntos
Microcorpos/metabolismo , Peroxinas/química , Peroxinas/metabolismo , Trypanosoma/crescimento & desenvolvimento , Regulação da Expressão Gênica , Genes Essenciais , Proteínas de Membrana/metabolismo , Viabilidade Microbiana , Modelos Moleculares , Peroxinas/genética , Estrutura Secundária de Proteína , Homologia Estrutural de Proteína , Trypanosoma/metabolismo
20.
Biosci Rep ; 39(6)2019 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-31160481

RESUMO

An explosion of sequence information in the genomics era has thrown up thousands of protein sequences without functional assignment. Though our ability to predict function based on sequence alone is improving steadily, we still have a long way to go. Proteins with common evolutionary origins carry telling sequence signatures, which ought to reveal their biological roles. These sequence signatures have allowed us to classify proteins into families with similar structures, and possibly, functions. Yet, evolution is a perpetual tinkerer, and hence, sequence signatures alone have proved inadequate in understanding the physiological activities of proteins. One such enigmatic family of enzymes is the NUDIX ( nu cleoside di phosphate linked to a moiety X ) hydrolase family that has over 80000 members from all branches of the tree of life. Though MutT, the founding member of this family, was identified in 1954, we are only now beginning to understand the diversity of substrates and biological roles that these enzymes demonstrate. In a recent article by Cordeiro et al. in Bioscience Reports [Biosci. Rep. (2019)], two members of this protein family from the human pathogen Trypanosoma brucei were deorphanized as being polyphosphate hydrolases. The authors show that of the five NUDIX hydrolases coded by the T. brucei genomes, TbNH2 and TbNH4, show in vitro hydrolytic activity against inorganic polyphosphate. Through classical biochemistry and immunostaining microscopy, differences in their substrate specificities and sub-cellular localization were revealed. These new data provide a compelling direction to the study of Trypanosome stress biology as well as our understanding of the NUDIX enzyme family.


Assuntos
Trypanosoma brucei brucei , Hidrolases Anidrido Ácido , Citosol , Humanos , Microcorpos , Polifosfatos , Pirofosfatases , Especificidade por Substrato
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