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1.
Mem. Inst. Oswaldo Cruz ; 113(8): e180086, 2018. tab, graf
Article Dans Anglais | LILACS | ID: biblio-1040598

Résumé

Dynamic S-palmitoylation of proteins is the addition of palmitic acid by zDHHC palmitoyl transferases (PATs) and depalmitoylation by palmitoyl protein thioesterases (PPTs). A putative PAT (TcPAT1) has been previously identified in Trypanosoma cruzi, the etiological agent of Chagas disease. Here we analyse other 14 putative TcPATs and 2 PPTs in the parasite genome. T. cruzi cell lines expressing TcPATs and TcPPTs plus a FLAG tag at the C terminus were produced for most enzymes, with positive detection by indirect immunofluorescence. Overexpressed TcPATs were mostly found as single spots at the parasite anterior end, while the TcPPTs were dispersed throughout the parasite body.


Sujets)
Palmitates/métabolisme , Trypanosoma cruzi/métabolisme , Protéines de protozoaire/métabolisme , Protéine S/métabolisme , Lipoylation/génétique , Trypanosoma cruzi/enzymologie , Trypanosoma cruzi/génétique , Protéines de protozoaire/génétique , Régulation de l'expression des gènes , Protéine S/génétique
2.
Mem. Inst. Oswaldo Cruz ; 113(12): e180377, 2018. graf
Article Dans Anglais | LILACS | ID: biblio-1040587

Résumé

Ascorbate peroxidase (APX) is a redox enzyme of the trypanothione pathway that converts hydrogen peroxide (H2O2) into water molecules. In the present study, the APX gene was overexpressed in Leishmania braziliensis to investigate its contribution to the trivalent antimony (SbIII)-resistance phenotype. Western blot results demonstrated that APX-overexpressing parasites had higher APX protein levels in comparison with the wild-type line (LbWTS). APX-overexpressing clones showed an 8-fold increase in the antimony-resistance index over the parental line. In addition, our results indicated that these clones were approximately 1.8-fold more tolerant to H2O2 than the LbWTS line, suggesting that the APX enzyme plays an important role in the defence against oxidative stress. Susceptibility tests revealed that APX-overexpressing L. braziliensis lines were more resistant to isoniazid, an antibacterial agent that interacts with APX. Interestingly, this compound enhanced the anti-leishmanial SbIII effect, indicating that this combination represents a good strategy for leishmaniasis chemotherapy. Our data demonstrate that APX enzyme is involved in the development of L. braziliensis antimony-resistance phenotype and may be an attractive therapeutic target in the design of new strategies for leishmaniasis treatment.


Sujets)
Leishmania brasiliensis/effets des médicaments et des substances chimiques , Leishmania brasiliensis/enzymologie , Ascorbate peroxidases/métabolisme , Antimoine/pharmacologie , Antiprotozoaires/pharmacologie , Phénotype , Résistance aux substances , Régulation de l'expression des gènes codant pour des enzymes , Protéines de protozoaire/métabolisme , Technique de Western , Stress oxydatif , Tests de sensibilité parasitaire
3.
Rev. bras. parasitol. vet ; 26(2): 185-204, Apr.-June 2017. tab, graf
Article Dans Anglais | LILACS | ID: biblio-899279

Résumé

Abstract Ornithodoros mimon is an argasid tick that parasitizes bats, birds and opossums and is also harmful to humans. Knowledge of the transcripts present in the tick gut helps in understanding the role of vital molecules in the digestion process and parasite-host relationship, while also providing information about the evolution of arthropod hematophagy. Thus, the present study aimed to know and ascertain the main molecules expressed in the gut of argasid after their blood meal, through analysis on the gut transcriptome of engorged females of O. mimon using 454-based RNA sequencing. The gut transcriptome analysis reveals several transcripts associated with hemoglobin digestion, such as serine, cysteine, aspartic proteases and metalloenzymes. The phylogenetic analysis on the peptidases confirmed that most of them are clustered with other tick genes. We recorded the presence a cathepsin O peptidase-coding transcript in ticks. The topology of the phylogenetic inferences, based on transcripts of inferred families of homologues, was similar to that of previous reports based on mitochondrial genome and nuclear rRNA sequences. We deposited 2,213 sequence of O. mimon to the public databases. Our findings may help towards better understanding of important argasid metabolic processes, such as digestion, nutrition and immunity.


Resumo Ornithodoros mimon é um carrapato argasídeo parasita de morcegos, aves e marsupiais, além de ser bastante agressivo aos humanos. O conhecimento dos transcritos presentes no intestino dos carrapatos auxilia no entendimento do papel de moléculas vitais no processo de digestão e na relação parasito-hospedeiro, além de fornecer também informações sobre a evolução dos artrópodes hematófagos. Desta maneira, o presente estudo teve como objetivo conhecer e identificar as principais moléculas expressas no intestino de uma espécie de carrapato argasídeo após o repasto sanguíneo, através de uma análise transcritômica descritiva do intestino de fêmeas ingurgitadas de O. mimon, utilizando um sequenciamento de RNA de nova geração da plataforma 454. Além de inferir a relação filogenética de carrapatos através de um conjunto de dados transcritômicos. O transcriptoma do intestino revelou diversos transcritos associados com a digestão da hemoglobina, como proteinases das classes serino, cisteína, aspártica e metalo. Registramos a presença de um transcrito de uma cisteína peptidase do tipo catepsina O em carrapatos. A inferência filogenética baseada em conjunto de dados transcritos homólogos tem uma resolução topológica similar a de outros conjuntos de dados moleculares. Foram depositados no banco de dados gênico público 2213 transcritos de O. mimon. Os achados obtidos no presente estudo podem contribuir para compreensão dos importantes processos, como digestão, nutrição e imunidade dos carrapatos da família Argasidae, além de fornecer informações sobre a filogenia da ordem Ixodida.


Sujets)
Animaux , Femelle , Protéines de protozoaire/métabolisme , Analyse de profil d'expression de gènes/médecine vétérinaire , Ornithodoros/métabolisme , Muqueuse intestinale/métabolisme , Phylogenèse , Protéines de protozoaire/génétique , Analyse de profil d'expression de gènes/méthodes , Ornithodoros/classification
4.
Braz. j. infect. dis ; 21(2): 125-132, Mar.-Apr. 2017. tab, graf
Article Dans Anglais | LILACS | ID: biblio-839198

Résumé

Abstract Resistance to benznidazole in certain strains of Trypanosoma cruzi may be caused by the increased production of enzymes that act on the oxidative metabolism, such as mitochondrial tryparedoxin peroxidase which catalyses the reduction of peroxides. This work presents cytotoxicity assays performed with ferrocenyl diamine hydrochlorides in six different strains of T. cruzi epimastigote forms (Y, Bolivia, SI1, SI8, QMII, and SIGR3). The last four strains have been recently isolated from triatominae and mammalian host (domestic cat). The expression of mitochondrial tryparedoxin peroxidase was analyzed by the Western blotting technique using polyclonal antibody anti mitochondrial tryparedoxin peroxidase obtained from a rabbit immunized with the mitochondrial tryparedoxin peroxidase recombinant protein. All the tested ferrocenyl diamine hydrochlorides were more cytotoxic than benznidazole. The expression of the 25.5 kDa polypeptide of mitochondrial tryparedoxin peroxidase did not increase in strains that were more resistant to the ferrocenyl compounds (SI8 and SIGR3). In addition, a 58 kDa polypeptide was also recognized in all strains. Ferrocenyl diamine hydrochlorides showed trypanocidal activity and the expression of 25.5 kDa mitochondrial tryparedoxin peroxidase is not necessarily increased in some T. cruzi strains. Most likely, other mechanisms, in addition to the over expression of this antioxidative enzyme, should be involved in the escape of parasites from cytotoxic oxidant agents.


Sujets)
Animaux , Chats , Lapins , Peroxidases/métabolisme , Composés du fer II/pharmacologie , Protéines de protozoaire/métabolisme , Oxydants/pharmacologie , Diamines/pharmacologie , Mitochondries/enzymologie , Trypanosoma cruzi/effets des médicaments et des substances chimiques , Trypanosoma cruzi/enzymologie , Technique de Western , Mitochondries/effets des médicaments et des substances chimiques
5.
Mem. Inst. Oswaldo Cruz ; 111(11): 670-675, Nov. 2016. graf
Article Dans Anglais | LILACS | ID: biblio-829246

Résumé

Nicotinamide/nicotinate adenine dinucleotide (NAD+/NaAD) performs essential functions in cell metabolism and energy production due to its redox properties. The nicotinamide/nicotinate mononucleotide adenylyltransferase (NMNAT, EC 2.7.7.1/18) enzyme catalyses the key step in the biosynthesis of NAD+. Previously, the enzyme NMNAT was identified in Trypanosoma cruzi (TcNMNAT), a pathogenic agent with epidemiological importance in Latin America. To continue with the functional characterisation of this enzyme, its subcellular location and its possible post-translational modifications were examined in this study. For this, polyclonal antibodies were generated in mice, with soluble and denatured recombinant protein being used to detect the parasite’s NMNAT. Immunodetection assays were performed on whole extracts of T. cruzi, and an approximation of its intracellular location was determined using confocal microscopy on wild and transgenic parasites, which revealed the cytosol distribution patterns. This localisation occurs according to the needs of the dinucleotides that exist in this compartment. Additionally, a bioinformatics study was performed as a first approach to establish the post-translational modifications of the enzyme. Possible phosphorylation events were experimentally analysed by western blot, highlighting TcNMNAT as a potential target for serine kinases.


Sujets)
Animaux , Nicotinamide nucleotide adenylyltransferase/métabolisme , Protéines de protozoaire/métabolisme , Trypanosoma cruzi/enzymologie , Séquence d'acides aminés , Cytosol/parasitologie , Interactions hôte-parasite , Souris , Souris de lignée BALB C , Nicotinamide nucleotide adenylyltransferase/isolement et purification , Phosphorylation , Protein-Serine-Threonine Kinases , Protéines de protozoaire/isolement et purification
6.
Mem. Inst. Oswaldo Cruz ; 110(7): 877-883, Nov. 2015. tab, graf
Article Dans Anglais | LILACS | ID: lil-764587

Résumé

Trichomonas vaginalis is a flagellate protozoan that parasitises the urogenital human tract and causes trichomoniasis. During the infection, the acquisition of nutrients, such as iron and purine and pyrimidine nucleosides, is essential for the survival of the parasite. The enzymes for purinergic signalling, including adenosine deaminase (ADA), which degrades adenosine to inosine, have been characterised in T. vaginalis. In the evaluation of the ADA profile in different T. vaginalisisolates treated with different iron sources or with limited iron availability, a decrease in activity and an increase in ADA gene expression after iron limitation by 2,2-bipyridyl and ferrozine chelators were observed. This supported the hypothesis that iron can modulate the activity of the enzymes involved in purinergic signalling. Under bovine serum limitation conditions, no significant differences were observed. The results obtained in this study allow for the assessment of important aspects of ADA and contribute to a better understanding of the purinergic system in T. vaginalis and the role of iron in establishing infection and parasite survival.


Sujets)
Animaux , Bovins , Femelle , Humains , Adenosine deaminase/métabolisme , Agents chélateurs du fer/pharmacologie , Trichomonas vaginalis/effets des médicaments et des substances chimiques , Trichomonas vaginalis/enzymologie , Adenosine deaminase/effets des médicaments et des substances chimiques , Régulation de l'expression des gènes codant pour des enzymes , Protéines de protozoaire/génétique , Protéines de protozoaire/métabolisme , RT-PCR , Trichomonas vaginalis/croissance et développement
7.
Clinics ; 70(3): 157-161, 03/2015. tab
Article Dans Anglais | LILACS | ID: lil-747105

Résumé

OBJECTIVE: To determine whether Tai Chi Chuan or ballroom dancing promotes better performance with respect to postural balance, gait, and postural transfer among elderly people. METHODS: We evaluated 76 elderly individuals who were divided into two groups: the Tai Chi Chuan Group and the Dance Group. The subjects were tested using the NeuroCom Balance Master¯ force platform system with the following protocols: static balance tests (the Modified Clinical Tests of Sensory Interaction on Balance and Unilateral Stance) and dynamic balance tests (the Walk Across Test and Sit-to-stand Transfer Test). RESULTS: In the Modified Clinical Test of Sensory Interaction on Balance, the Tai Chi Chuan Group presented a lower sway velocity on a firm surface with open and closed eyes, as well as on a foam surface with closed eyes. In the Modified Clinical Test of Sensory Interaction on Unilateral Stance, the Tai Chi Chuan Group presented a lower sway velocity with open eyes, whereas the Dance Group presented a lower sway velocity with closed eyes. In the Walk Across Test, the Tai Chi Chuan Group presented faster walking speeds than those of the Dance Group. In the Sit-to-stand Transfer Test, the Tai Chi Chuan Group presented shorter transfer times from the sitting to the standing position, with less sway in the final standing position. CONCLUSION: The elderly individuals who practiced Tai Chi Chuan had better bilateral balance with eyes open on both types of surfaces compared with the Dance Group. The Dance Group had better unilateral postural balance with eyes closed. The Tai Chi Chuan Group had faster walking speeds, shorter transfer times, and better postural balance in the final standing position during the Sit-to-stand Test. .


Sujets)
/métabolisme , AMP cyclique/métabolisme , Dictyostelium/enzymologie , Dictyostelium/génétique , Sous-unités alpha Gi-Go des protéines G/métabolisme , Protéines de protozoaire/métabolisme , /génétique , Dictyostelium/croissance et développement , Dictyostelium/métabolisme , Régulation négative/effets des médicaments et des substances chimiques , Protéines de la matrice extracellulaire/génétique , Protéines de la matrice extracellulaire/métabolisme , Acide folique/pharmacologie , /déficit , /génétique , /métabolisme , Sous-unités alpha Gi-Go des protéines G/déficit , Sous-unités alpha Gi-Go des protéines G/génétique , Mutation , Mitogen-Activated Protein Kinase 1/génétique , Mitogen-Activated Protein Kinase 1/métabolisme , Protéines de protozoaire/génétique , Transduction du signal , Spores de protozoaire/enzymologie , Spores de protozoaire/génétique , Complexe vitaminique B/pharmacologie
8.
Indian J Biochem Biophys ; 2014 Dec ; 51 (6): 559-566
Article Dans Anglais | IMSEAR | ID: sea-156537

Résumé

In addition to well-known process of proteasome-mediated degradation of polyubiquitinated proteins, monoubiquitination of proteins is also an important post-translational modification that regulates various non-degradative cellular processes like protein trafficking, cellular signalling, DNA replication and DNA repair. We have previously characterized a multi-domain cycling sequence binding protein LdCSBP from Leishmania donovani, which binds specifically to a conserved CAUAGAAG octamer containing RNAs via its uniquely arranged CCCH type Zn-fingers and degrades them using its Smr endonuclease domain, indicative of its potential role in the turnover of the S-phase mRNAs. Remarkably, its riboendonuclease activity is inhibited due to the incorporation of a monoubiquitin residue in the ZnF domain, though the target Lys residue remains unknown. Here, we report through systematic mutation of Lys residue to Ala that Lys-413 in LdCSBP is the site of monoubiquitination. However, the amino acid motif around the target Lys in LdCSBP is not consensus with any previously known monoubiquitination site, though partial homology is observed with a subset of recently identified mammalian ubiquitination target sites. Interestingly, Lys-413 of LdCSBP is conserved in the homologous annotated proteins from the related kinetoplastida parasites, suggesting similar monoubiquitination-mediated regulation of RNA endonuclease activity in the organisms.


Sujets)
Séquence d'acides aminés , Sites de fixation , Endonucleases/composition chimique , Endonucleases/génétique , Endonucleases/métabolisme , Leishmania donovani/cytologie , Leishmania donovani/physiologie , Lysine/composition chimique , Lysine/génétique , Lysine/métabolisme , Données de séquences moléculaires , Liaison aux protéines , Motifs et domaines d'intéraction protéique , Protéines de protozoaire/métabolisme , Protéines de liaison à l'ARN , Phase S/physiologie , Relation structure-activité , Ubiquitination , Doigts de zinc
9.
Invest. clín ; 54(3): 270-283, sep. 2013. ilus
Article Dans Espagnol | LILACS | ID: lil-740325

Résumé

Mediante dos métodos de ensayo de peptidasas, uno en fase líquida y otro en fase gel (zimografía en geles), se detectó una peptidasa, en extractos proteicos crudos de epimastigotes de Trypanosoma cruzi, provenientes de un área rural de Venezuela endémica para el mal de Chagas. La peptidasa mostró actividad en el intervalo de pH comprendido entre 2,0 y 2,9. Bajo las condiciones experimentales descritas, la peptidasa resultó insensible a concentraciones usuales de inhibidores clásicos de peptidasas de tipo: serina, cisteína, metalo-peptidasas y aspártico. No obstante, a semejanza de la pepsina porcina a pH 2,9, la peptidasa es inhibida en presencia de 5mM DTT.


Through two peptidase assay methods, one in liquid-phase and another, in gel-phase (gel zymography), an acid peptidase was detected in protein crude extracts of epimastigotes of Trypanosoma cruzi, from a rural area of Venezuela where Chagas disease is endemic. The peptidase shows activity at a pH range between 2.0 and 2.9. Under the experimental conditions described, the acid peptidase was insensitive to usual concentrations of peptidase inhibitors of the types: serine, cysteine, aspartic and metallo-peptidases. Nevertheless, like porcine pepsin at pH 2.9, the peptidase was inhibited in the presence of 5mM DTT.


Sujets)
Humains , Peptide hydrolases/isolement et purification , Protéines de protozoaire/isolement et purification , Trypanosoma cruzi/enzymologie , Maladie de Chagas/parasitologie , Maladies endémiques , Concentration en ions d'hydrogène , Hydrolyse , Hémoglobines/métabolisme , Pepstatines/pharmacologie , Peptide hydrolases/métabolisme , Inhibiteurs de protéases/pharmacologie , Protéines de protozoaire/antagonistes et inhibiteurs , Protéines de protozoaire/métabolisme , Spécificité du substrat , Trypanosoma cruzi/croissance et développement , Trypanosoma cruzi/isolement et purification , Venezuela
10.
Mem. Inst. Oswaldo Cruz ; 108(5): 631-636, ago. 2013. graf
Article Dans Anglais | LILACS | ID: lil-680777

Résumé

Heteroxenic and monoxenic trypanosomatids were screened for the presence of actin using a mouse polyclonal antibody produced against the entire sequence of the Trypanosoma cruzi actin gene, encoding a 41.9 kDa protein. Western blot analysis showed that this antibody reacted with a polypeptide of approximately 42 kDa in the whole-cell lysates of parasites targeting mammals (T. cruzi, Trypanosoma brucei and Leishmania major), insects (Angomonas deanei, Crithidia fasciculata, Herpetomonas samuelpessoai and Strigomonas culicis) and plants (Phytomonas serpens). A single polypeptide of approximately 42 kDa was detected in the whole-cell lysates of T. cruzi cultured epimastigotes, metacyclic trypomastigotes and amastigotes at similar protein expression levels. Confocal microscopy showed that actin was expressed throughout the cytoplasm of all the tested trypanosomatids. These data demonstrate that actin expression is widespread in trypanosomatids.


Sujets)
Animaux , Souris , Actines/métabolisme , Trypanosomatina/métabolisme , Technique de Western , Électrophorèse sur gel de polyacrylamide , Technique d'immunofluorescence , Microscopie confocale , Protéines de protozoaire/métabolisme
11.
Mem. Inst. Oswaldo Cruz ; 107(6): 790-799, set. 2012. ilus, graf, tab
Article Dans Anglais | LILACS | ID: lil-649496

Résumé

Trypanosomes are parasitic protozoa in which gene expression is primarily controlled through the regulation of mRNA stability and translation. This post-transcriptional control is mediated by various families of RNA-binding proteins, including those with zinc finger CCCH motifs. CCCH zinc finger proteins have been shown to be essential to differentiation events in trypanosomatid parasites. Here, we functionally characterise TcZFP2 as a predicted post-transcriptional regulator of differentiation in Trypanosoma cruzi. This protein was detected in cell culture-derived amastigotes and trypomastigotes, but it was present in smaller amounts in metacyclic trypomastigote forms of T. cruzi. We use an optimised recombinant RNA immunopreciptation followed by microarray analysis assay to identify TcZFP2 target mRNAs. We further demonstrate that TcZFP2 binds an A-rich sequence in which the adenosine residue repeats are essential for high-affinity recognition. An analysis of the expression profiles of the genes encoding the TcZFP2-associated mRNAs throughout the parasite life cycle by microarray hybridisation showed that most of the associated mRNAs were upregulated in the metacyclic trypomastigote forms, also suggesting a role for TcZFP2 in metacyclic trypomastigote differentiation. Knockdown of the orthologous Trypanosoma brucei protein levels showed ZFP2 to be a positive regulator of specific target mRNA abundance.


Sujets)
Protéines de liaison à l'ADN/métabolisme , Protéines de protozoaire/métabolisme , ARN messager/métabolisme , Protéines de liaison à l'ARN/métabolisme , Trypanosoma cruzi/métabolisme , Régulation de l'expression des gènes au cours du développement , Stabilité de l'ARN , Trypanosoma cruzi/croissance et développement
12.
The Korean Journal of Parasitology ; : 365-369, 2012.
Article Dans Anglais | WPRIM | ID: wpr-69772

Résumé

Acanthamoeba spp. are single-celled protozoan organisms that are widely distributed in the environment. In this study, to understand functional roles of a mannose-binding protein (MBP), Acanthamoeba castellanii was treated with methyl-alpha-D-mannopyranoside (mannose), and adhesion and cytotoxicity of the amoeba were analyzed. In addition, to understand the association of MBP for amoeba phagocytosis, phagocytosis assay was analyzed using non-pathogenic bacterium, Escherichia coli K12. Amoebae treated with mannose for 20 cycles exhibited larger vacuoles occupying the most area of the amoebic cytoplasm in comparison with the control group amoebae and glucose-treated amoebae. Mannose-selected amoebae exhibited lower levels of binding to Chinese hamster ovary (CHO) cells. Exogenous mannose inhibited >50% inhibition of amoebae (control group) binding to CHO cells. Moreover, exogenous mannose inhibited amoebae (i.e., man-treated) binding to CHO cells by <15%. Mannose-selected amoebae exhibited significantly decreased cytotoxicity to CHO cells compared with the control group amoebae, 25.1% vs 92.1%. In phagocytic assay, mannose-selected amoebae exhibited significant decreases in bacterial uptake in comparison with the control group, 0.019% vs 0.03% (P<0.05). Taken together, it is suggested that mannose-selected A. castellanii trophozoites should be severely damaged and do not well interact with a target cell via a lectin of MBP.


Sujets)
Animaux , Cricetinae , Femelle , Acanthamoeba castellanii/effets des médicaments et des substances chimiques , Amibiase/parasitologie , Cellules CHO , Adhérence cellulaire/effets des médicaments et des substances chimiques , Survie cellulaire , Cricetulus , Escherichia coli K12/métabolisme , Mannose/pharmacologie , Lectine liant le mannose/métabolisme , Phagocytose , Protéines de protozoaire/métabolisme
13.
Article Dans Anglais | IMSEAR | ID: sea-135347

Résumé

Visceral leishmaniasis (VL) or kala-azar is a chronic protozoan infection in humans associated with significant global morbidity and mortality. The causative agent is a haemoflagellate protozoan Leishmania donovani, an obligate intracellular parasite that resides and multiplies within macrophages of the reticulo-endothelial system. Most of the existing anti-leishmanial drugs have serious side effects that limit their clinical application. As an alternate strategy, vaccination is also under experimental and clinical trials. The in vitro evaluation designed to facilitate rapid testing of a large number of drugs has been focussed on the promastigotes milt little attention on the clinically relevant parasite stage, amastigotes. Screening designed to closely reflect the situation in vivo is currently time consuming, laborious, and expensive, since it requires intracellular amastigotes and animal model. The ability to select transgenic Leishmania expressing reporter proteins, such as the green fluorescent proteins (GFP) or the luciferase opened up new possibilities for the development of drug screening models. Many experimental animal models like rodents, dogs and monkeys have been developed, each with specific features, but none accurately reproduces what happens in humans. Available in vitro and in vivo methodologies for antileishmanial drug screening and their respective advantages and disadvantages are reviewed.


Sujets)
Animaux , Animal génétiquement modifié , Antiprotozoaires/pharmacologie , Antiprotozoaires/usage thérapeutique , Essais cliniques comme sujet , Découverte de médicament , Évaluation préclinique de médicament/méthodes , Gènes rapporteurs , Tests de criblage à haut débit , Humains , Leishmania donovani/effets des médicaments et des substances chimiques , Leishmania donovani/génétique , Leishmania donovani/physiologie , Leishmaniose viscérale/traitement médicamenteux , Protéines de protozoaire/génétique , Protéines de protozoaire/métabolisme
14.
Mem. Inst. Oswaldo Cruz ; 105(3): 341-347, May 2010. ilus, graf
Article Dans Anglais | LILACS | ID: lil-547313

Résumé

Kinetoplastid membrane protein-11 (KMP-11), a protein present in all kinetoplastid protozoa, is considered a potential candidate for a leishmaniasis vaccine. A suitable leishmaniasis vaccine candidate molecule must be expressed in amastigotes, the infective stage for mammals. However, the expression of KMP-11 in Leishmania amastigotes has been a subject of controversy. We evaluated the expression of this molecule in logarithmic and stationary growth phase promastigotes, as well as in amastigotes, of Leishmania amazonensis by immunoblotting, flow cytometry and immunocytochemistry, using a monoclonal antibody against KMP-11. We found that KMP-11 is present in promastigotes and amastigotes. In both stages, the protein was found in association with membrane structures (at the cell surface, flagellar pocket and intracellular vesicles). More importantly, its surface expression is higher in amastigotes than in promastigotes and increases during metacyclogenesis. The increased expression of KMP-11 in metacyclic promastigotes, and especially in amastigotes, indicates a role for this molecule in the parasite relationship with the mammalian host. The presence of this molecule in amastigotes is consistent with the previously demonstrated immunoprotective capacity of vaccine prototypes based on the KMP-11-coding gene and the presence of humoral and cellular immune responses to KMP-11 in Leishmania-infected humans and animals.


Sujets)
Animaux , Femelle , Souris , Leishmania mexicana/croissance et développement , Protéines membranaires/métabolisme , Protéines de protozoaire/métabolisme , Technique de Western , Cytométrie en flux , Immunochimie , Leishmania mexicana/composition chimique , Souris de lignée BALB C , Microscopie électronique
15.
Mem. Inst. Oswaldo Cruz ; 104(supl.1): 295-300, July 2009. ilus, tab, graf
Article Dans Anglais | LILACS | ID: lil-520892

Résumé

Trypanosoma cruzi proline racemases (TcPRAC) are homodimeric enzymes that interconvert the L and D-enantiomers of proline. At least two paralogous copies of proline racemase (PR) genes are present per parasite haploid genome and they are differentially expressed during T. cruzi development. Non-infective epimastigote forms that overexpress PR genes differentiate more readily into metacyclic infective forms that are more invasive to host cells, indicating that PR participates in mechanisms of virulence acquisition. Using a combination of biochemical and enzymatic methods, we show here that, in addition to free D-amino acids, non-infective epimastigote and infective metacyclic parasite extracts possess peptides composed notably of D-proline. The relative contribution of TcPRAC to D-proline availability and its further assembly into peptides was estimated through the use of wild-type parasites and parasites over-expressing TcPRAC genes. Our data suggest that D-proline-bearing peptides, similarly to the mucopeptide layer of bacterial cell walls, may be of benefit to T. cruzi by providing resistance against host proteolytic mechanisms.


Sujets)
Amino-acid isomerases/génétique , Protéines de protozoaire/composition chimique , Trypanosoma cruzi/composition chimique , Amino-acid isomerases/métabolisme , Régulation de l'expression des gènes , Protéines de protozoaire/génétique , Protéines de protozoaire/métabolisme , Trypanosoma cruzi/génétique , Trypanosoma cruzi/métabolisme
16.
Mem. Inst. Oswaldo Cruz ; 104(2): 155-161, Mar. 2009. ilus
Article Dans Anglais | LILACS | ID: lil-533501

Résumé

Parasite differentiation from proliferating tachyzoites into latent bradyzoites is central to pathogenesis and transmission of the intracellular protozoan pathogen Toxoplasma gondii. The presence of bradyzoite-containing cysts in human hosts and their subsequent rupture can cause life-threatening recrudescence of acute infection in the immunocompromised and cyst formation in other animals contributes to zoonotic transmission and widespread dissemination of the parasite. In this review, we discuss the evidence showing how the clinically relevant process of bradyzoite differentiation is regulated at both transcriptional and post-transcriptional levels. Specific regulatory factors implicated in modulating bradyzoite differentiation include promoter-based cis-elements, epigenetic modifications and protein translation control through eukaryotic initiation factor -2 (eIF2). In addition to a summary of the current state of knowledge in these areas we discuss the pharmacological ramifications and pose some questions for future research.


Sujets)
Animaux , Humains , Toxoplasma/pathogénicité , Différenciation cellulaire , Épigenèse génétique , /génétique , /métabolisme , Protéines de protozoaire/génétique , Protéines de protozoaire/métabolisme , Transduction du signal , Activation de la transcription , Toxoplasma/cytologie , Toxoplasma/génétique
17.
Indian J Biochem Biophys ; 2009 Feb; 46(1): 86-92
Article Dans Anglais | IMSEAR | ID: sea-26312

Résumé

The recent upsurge of antimony (Sb) resistance is a major impediment to successful chemotherapy of visceral leishmaniasis (VL). Mechanisms involved in antimony resistance have demonstrated an upregulation of drug efflux pumps; however, the biological role drug efflux pumps in clinical isolates remains to be substantiated. Thus, in this study, the functionality of drug efflux pumps was measured in promastigotes and axenic amastigotes isolated from VL patients, who were either Sb-sensitive (AG83, 2001 and MC9) or resistant (NS2, 41 and GE1) using rhodamine123 as a substrate for multidrug resistant (MDR) pumps and calcein as a substrate for multidrug resistance-associated proteins (MRP) respectively; their specificity was confirmed using established blockers. Sb-resistant (Sb-R) isolates accumulated higher amounts of R123, as compared to Sb-sensitive (Sb-S) isolates. Verapamil, a MDR inhibitor failed to alter R123 accumulation, suggesting absence of classical MDR activity. In Sb-R isolates, both promastigotes and axenic amastigotes accumulated significantly lower amounts of calcein than Sb-S isolates and probenecid, an established pan MRP blocker, marginally increased calcein accumulation. Depletion of ATP dramatically increased calcein accumulation primarily in Sb-R isolates, indicating existence of a MRP-like pump, which was more active in Sb-R isolates. In conclusion, our data suggested that overfunctioning of a MRP-like pump contributed towards generation of Sb-R phenotype in L. donovani field isolates.


Sujets)
Transporteurs ABC/métabolisme , Adénosine triphosphate/métabolisme , Animaux , Antimoine/pharmacologie , Antiprotozoaires/pharmacologie , Multirésistance aux médicaments , Fluorescéines/métabolisme , Humains , Leishmania donovani/effets des médicaments et des substances chimiques , Leishmania donovani/métabolisme , Leishmaniose viscérale/traitement médicamenteux , Leishmaniose viscérale/parasitologie , Leishmaniose viscérale/physiopathologie , Protéines associées à la multirésistance aux médicaments/antagonistes et inhibiteurs , Protéines associées à la multirésistance aux médicaments/métabolisme , Ofloxacine/pharmacologie , Probénécide/pharmacologie , Protéines de protozoaire/métabolisme , Rhodamine 123/métabolisme , Vérapamil/pharmacologie
18.
The Korean Journal of Parasitology ; : S29-S37, 2009.
Article Dans Anglais | WPRIM | ID: wpr-14772

Résumé

The dense granule of Toxoplasma gondii is a secretory vesicular organelle of which the proteins participate in the modification of the parasitophorous vacuole (PV) and PV membrane for the maintenance of intracellular parasitism in almost all nucleated host cells. In this review, the archives on the research of GRA proteins are reviewed on the foci of finding GRA proteins, characterizing molecular aspects, usefulness in diagnostic antigen, and vaccine trials in addition to some functions in host-parasite interactions.


Sujets)
Animaux , Humains , Antigènes de protozoaire/métabolisme , Granulations cytoplasmiques/métabolisme , Interactions hôte-parasite , Protéines de protozoaire/métabolisme , Toxoplasma/métabolisme , Toxoplasmose/parasitologie , Vacuoles/métabolisme
19.
Indian J Biochem Biophys ; 2008 Dec; 45(6): 365-73
Article Dans Anglais | IMSEAR | ID: sea-27212

Résumé

Protein trafficking in the malarial parasite Plasmodium falciparum is dictated by a complex life-cycle that involves a variety of intra-cellular and host cell destinations, such as the mitochondrion, apicoplast, rhoptries and micronemes. Of these, the apicoplast and mitochondrion are believed to account for more than 10% of this traffic. Studies have shown that mechanisms for mitochondrion and apicoplast targeting are distinct, despite their close physical proximity. The heme biosynthesis pathway spans both these organelles, making trafficking studies crucial for the spatial demarcation of the constituent interactions. This minireview highlights the challenges in identifying the possible sub-cellular destinations of the heme pathway enzymes using gleanings from literature survey as well as focussed bioinformatic analysis.


Sujets)
Séquence d'acides aminés , Animaux , Hème/biosynthèse , Mitochondries/métabolisme , Données de séquences moléculaires , Plasmodium falciparum/enzymologie , Transport des protéines , Protéines de protozoaire/métabolisme
20.
Genet. mol. res. (Online) ; 7(2): 305-313, 2008. ilus
Article Dans Anglais | LILACS | ID: lil-641009

Résumé

Toxoplasma gondii is an intracellular obligate protozoan, which infects humans and warm-blooded animals. The aim of the present study was to clone the rop2, gra5 and gra7 genes from T. gondii RH strain and to produce recombinant proteins. The rop2, gra5 and gra7 gene fragments produced by polymerase chain reaction were cloned into the pET102/D-TOPO® vector which contains thioredoxin and polyhistidine tags at the C- and N-ends, respectively, and is expressed in Escherichia coli BL21(DE-3). The expression fusion proteins were found almost entirely in the insoluble form in the cell lysate. These recombinant proteins were purified with an Ni-NTA column. Concentrations of the recombinant antigens produced in the E. coli BL21-star ranged from 300 to 500 μg/ml growth media, which was used to immunize rabbits. We observed an identity ranging from 96 to 97% when nucleotide sequences were compared to GenBank database sequences. Immunocharacterization of proteins was made by indirect immunofluorescence assay. These proteins will be used for serodiagnosis and vaccination.


Sujets)
Animaux , Antigènes de protozoaire/génétique , Protéines membranaires/génétique , Protéines de protozoaire/génétique , Toxoplasma/génétique , Antigènes de protozoaire/immunologie , Antigènes de protozoaire/métabolisme , Technique de Western , Clonage moléculaire , Électrophorèse sur gel de polyacrylamide , Technique d'immunofluorescence indirecte , Séquençage par oligonucléotides en batterie , Protéines de fusion recombinantes/génétique , Protéines de fusion recombinantes/immunologie , Protéines de fusion recombinantes/métabolisme , Protéines membranaires/immunologie , Protéines membranaires/métabolisme , Protéines de protozoaire/immunologie , Protéines de protozoaire/métabolisme , Toxoplasma/immunologie , Toxoplasma/métabolisme
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