Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 8.913
Filtrar
1.
Gene ; 716: 144016, 2019 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-31377318

RESUMO

Drug resistance of malaria parasites remains a problem affecting antimalarial treatment and control of the disease. We previously synthesized an antimalarial endoperoxide, N-89, having high antimalarial effects in vitro and in vivo. In this study we seek to understand the resistant mechanism against N-89 by establishing a highly N-89-resistant clone, named NRC10H, of the Plasmodium falciparum FCR-3 strain. We describe gene mutations in the parent FCR-3 strain and the NRC10H clone using whole-genome sequencing and subsequently by expression profiling using quantitative real-time PCR. Seven genes related to drug resistance, proteolysis, glycophosphatidylinositol anchor biosynthesis, and phosphatidylethanolamine biosynthesis exhibited a single amino acid substitution in the NRC10H clone. Among these seven genes, the multidrug resistance protein 2 (mdr2) variant A532S was found only in NRC10H. The genetic status of the P. falciparum endoplasmic reticulum-resident calcium binding protein (PfERC), a potential target of N-89, was similar between the NRC10H clone and the parent FCR-3 strain. These findings suggest that the genetic alterations of the identified seven genes, in particular mdr2, in NRC10H could give rise to resistance of the antimalarial endoperoxide N-89.


Assuntos
Antimaláricos/farmacologia , Compostos Heterocíclicos com 2 Anéis/farmacologia , Plasmodium falciparum/efeitos dos fármacos , Compostos de Espiro/farmacologia , Resistência a Medicamentos/genética , Genômica , Plasmodium falciparum/genética , Plasmodium falciparum/metabolismo , Proteínas de Protozoários/genética , Proteínas de Protozoários/metabolismo , RNA Mensageiro/metabolismo , Sequenciamento Completo do Genoma
2.
Microbiol Res ; 227: 126293, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31421715

RESUMO

T. gondii is a major opportunistic pathogen chronically infecting nearly one third of the world's population. Due to the high infection and mortality rates in immunocompromised patients and newborns, the extent or magnitude of T. gondii pathogenesis is determined mainly by host-pathogen interactions. T. gondii utilizes specialized secretory proteins to modify host cellular factors and facilitate invasion and replication. This review provides update on the recent progress in this field of research with particular emphasis on the T. gondii secretory proteins and their role in invasion and pathogenesis.


Assuntos
Transporte Proteico/fisiologia , Proteínas de Protozoários/metabolismo , Toxoplasma/fisiologia , Toxoplasma/patogenicidade , Animais , Interações Hospedeiro-Parasita , Humanos , Estágios do Ciclo de Vida , Toxoplasmose/parasitologia
3.
Exp Parasitol ; 204: 107731, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31374185

RESUMO

Neospora caninum is an obligate intracellular parasite related to cases of abortion and fertility impairment in cattle. The control of the parasite still lacks an effective protective strategy and the understanding of key mechanisms for host infection might be crucial for identification of specific targets. There are many proteins related to important mechanisms in the host cell infection cycle such as adhesion, invasion, proliferation and immune evasion. The surface proteins, especially SRS (Surface Antigen Glycoprotein - Related Sequences), have been demonstrated to have a pivotal role in the adhesion and invasion processes, making them potential anti-parasite targets. However, several predicted surface proteins were not described concerning their function and importance in the parasite life cycle. As such, a novel SRS protein, NcSRS57, was described. NcSRS57 antiserum was used to detect SRS proteins by immunofluorescence in parasites treated or not with phosphatidylinositol-specific phospholipase C (PI-PLC). The treatment with PI-PLC also allowed the identification of NcSRS29B and NcSRS29C, which were the most abundant SRS proteins in the soluble fraction. Our data indicated that SRS proteins in N. caninum shared a high level of sequence similarity and were susceptible to PI-PLC. In addition, the description of the SRS members, regarding abundance, function and immunogenicity will be useful in guiding specific methods to control the mechanism of adhesion and invasion mediated by these surface proteins.


Assuntos
Antígenos de Protozoários/metabolismo , Antígenos de Superfície/metabolismo , Neospora/química , Fosfoinositídeo Fosfolipase C/farmacologia , Proteínas de Protozoários/metabolismo , Animais , Antígenos de Protozoários/genética , Antígenos de Protozoários/imunologia , Antígenos de Superfície/genética , Antígenos de Superfície/imunologia , Cercopithecus aethiops , Clonagem Molecular , DNA de Protozoário/isolamento & purificação , Eletroforese em Gel Bidimensional , Eletroforese em Gel de Poliacrilamida , Soros Imunes/imunologia , Soros Imunes/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Microscopia Confocal , Neospora/efeitos dos fármacos , Neospora/genética , Neospora/imunologia , Fosfoinositídeo Fosfolipase C/metabolismo , Proteínas de Protozoários/genética , Proteínas de Protozoários/imunologia , Espectrometria de Massas em Tandem , Fosfolipases Tipo C/metabolismo , Fosfolipases Tipo C/farmacologia , Células Vero
4.
Mem Inst Oswaldo Cruz ; 114: e190111, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31433006

RESUMO

BACKGROUND: In addition to the limited therapeutic arsenal and the side effects of antileishmanial agents, drug resistance hinders disease control. In Brazil, Leishmania braziliensis causes atypical (AT) tegumentary leishmaniasis lesions, frequently refractory to treatment. OBJECTIVES: The main goal of this study was to characterise antimony (Sb)-resistant (SbR) L. braziliensis strains obtained from patients living in Xakriabá indigenous community, Minas Gerais, Brazil. METHODS: The aquaglyceroporin 1-encoding gene (AQP1) from L. braziliensis clinical isolates was sequenced, and its function was evaluated by hypo-osmotic shock. mRNA levels of genes associated with Sb resistance were measured by quantitative reverse transcription polymerase chain reaction (qRT-PCR). Atomic absorption was used to measure Sb uptake. FINDINGS: Although clinical isolates presented delayed recovery time in hypo-osmotic shock, AQP1 function was maintained. Isolate 340 accumulated less Sb than all other isolates, supporting the 65-fold downregulation of AQP1 mRNA levels. Both 330 and 340 isolates upregulated antimony resistance marker (ARM) 56/ARM58 and multidrug resistant protein A (MRPA); however, only ARM58 upregulation was an exclusive feature of SbR field isolates. CA7AE seemed to increase drug uptake in L. braziliensis and represented a tool to study the role of glycoconjugates in Sb transport. MAIN CONCLUSIONS: There is a clear correlation between ARM56/58 upregulation and Sb resistance in AT-harbouring patients, suggesting the use of these markers as potential indicators to help the treatment choice and outcome, preventing therapeutic failure.


Assuntos
Antimônio/farmacologia , Resistência a Medicamentos/genética , Leishmania braziliensis/efeitos dos fármacos , Leishmaniose Cutânea/parasitologia , Proteínas de Protozoários/genética , Tripanossomicidas/farmacologia , Aquagliceroporinas/metabolismo , Resistência a Medicamentos/efeitos dos fármacos , Humanos , Leishmania braziliensis/genética , Testes de Sensibilidade Parasitária , Proteínas de Protozoários/metabolismo , Reação em Cadeia da Polimerase em Tempo Real
5.
Chem Commun (Camb) ; 55(64): 9535-9538, 2019 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-31334508

RESUMO

Endoperoxide-containing antimalarials, such as artemisinin and the synthetic trioxolane OZ439, are prodrugs activated by heme to generate primary and secondary carbon-centered radicals. We employed activity-based protein profiling (ABPP) to show that the secondary-carbon-centered radical of 1,2,4-trioxolanes is primarily responsible for protein labeling in malaria parasites.


Assuntos
Carbono/metabolismo , Plasmodium falciparum/metabolismo , Proteínas de Protozoários/metabolismo , Animais
6.
Gene ; 710: 279-290, 2019 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-31200083

RESUMO

Plants are frequently exposed to variable environmental stresses that adversely affect plant growth, development and agricultural production. In this study, a trypanothione synthetase gene from Trypanosoma cruzi, TcTryS, was chemically synthesized and its roles in tolerance to multiple abiotic stresses were functionally characterized by generating transgenic rice overexpressing TcTryS. Overexpression of TcTryS in rice endows transgenic plants with hypersensitivity to ABA, hyposensitivity to NaCl- and mannitol-induced osmotic stress at the seed germination stage. TcTryS overexpression results in enhanced tolerance to drought, salt, cadmium, and 2,4,6-trichlorophenol stresses in transgenic rice, simultaneously supported by improved physiological traits. The TcTryS-overexpression plants also accumulated greater amounts of proline, less malondialdehyde and more transcripts of stress-related genes than wild-type plants under drought and salt stress conditions. In addition, TcTryS might play a positive role in maintaining chlorophyll content under 2,4,6-trichlorophenol stress. Histochemical staining assay showed that TcTryS renders transgenic plants better ROS-scavenging capability. All of these results suggest that TcTryS could function as a key regulator in modulation of abiotic stress tolerance in plant, and may have applications in the engineering of economically important crops.


Assuntos
Amida Sintases/genética , Amida Sintases/metabolismo , Oryza/genética , Estresse Fisiológico , Trypanosoma cruzi/enzimologia , Ácido Abscísico/farmacologia , Cádmio/toxicidade , Secas , Regulação da Expressão Gênica de Plantas , Oryza/crescimento & desenvolvimento , Plantas Geneticamente Modificadas/crescimento & desenvolvimento , Proteínas de Protozoários/genética , Proteínas de Protozoários/metabolismo , Tolerância ao Sal , Trypanosoma cruzi/genética , Regulação para Cima
7.
Parasit Vectors ; 12(1): 317, 2019 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-31234897

RESUMO

Glycophorins are heavily glycosylated sialoglycoproteins of human and animal erythrocytes. In humans, there are four glycophorins: A, B, C and D. Glycophorins play an important role in the invasion of red blood cells (RBCs) by malaria parasites, which involves several ligands binding to RBC receptors. Four Plasmodium falciparum merozoite EBL ligands have been identified: erythrocyte-binding antigen-175 (EBA-175), erythrocyte-binding antigen-181 (EBA-181), erythrocyte-binding ligand-1 (EBL-1) and erythrocyte-binding antigen-140 (EBA-140). It is generally accepted that glycophorin A (GPA) is the receptor for P. falciparum EBA-175 ligand. It has been shown that α(2,3) sialic acid residues of GPA O-glycans form conformation-dependent clusters on GPA polypeptide chain which facilitate binding. P. falciparum can also invade erythrocytes using glycophorin B (GPB), which is structurally similar to GPA. It has been shown that P. falciparum EBL-1 ligand binds to GPB. Interestingly, a hybrid GPB-GPA molecule called Dantu is associated with a reduced risk of severe malaria and ameliorates malaria-related morbidity. Glycophorin C (GPC) is a receptor for P. falciparum EBA-140 ligand. Likewise, successful binding of EBA-140 depends on sialic acid residues of N- and O-linked oligosaccharides of GPC, which form a cluster or a conformational structure depending on the presence of peptide fragment encompassing amino acids (aa) 36-63. Evaluation of the homologous P. reichenowi EBA-140 unexpectedly revealed that the chimpanzee homolog of human glycophorin D (GPD) is probably the receptor for this ligand. In this review, we concentrate on the role of glycophorins as erythrocyte receptors for Plasmodium parasites. The presented data support the long-lasting idea of high evolutionary pressure exerted by Plasmodium on the human glycophorins, which emerge as important receptors for these parasites.


Assuntos
Proteínas de Transporte/metabolismo , Eritrócitos/metabolismo , Eritrócitos/parasitologia , Glicoforina/metabolismo , Plasmodium falciparum/fisiologia , Proteínas de Protozoários/metabolismo , Receptores de Superfície Celular/metabolismo , Animais , Proteínas de Transporte/genética , Glicoforina/genética , Humanos , Ligantes , Merozoítos , Pan troglodytes , Ligação Proteica , Proteínas de Protozoários/genética , Receptores de Superfície Celular/genética
8.
Mol Biol (Mosk) ; 53(3): 446-455, 2019.
Artigo em Russo | MEDLINE | ID: mdl-31184610

RESUMO

Ran is an evolutionarily conserved GTPase crucial in regulating various cell divisions, including mitosis and meiosis. A previous study showed that the knockdown of RAN1 inhibited macronuclear amitosis with the abnormal organization of intramacronuclear microtubules in Tetrahymena thermophila. This study aimed to further investigate the effects of the inducible expression of wild-type Ran1 (Ran1WT), GTP-bound Ran1-mimetic (Ran1Q70L), and GDP-bound Ran1-mimetic (Ran1T25N) on cytoplasmic microtubule assembly during amitosis of T. thermophila, based on previous studies about their effects on intramacronuclear microtubule. The mutant strains of T. thermophila for inducible expression of Ran1WT/T25N/Q70L by Cd^(2+) were constructed. The inducibly expressed HA-Ran1Q70L/T25N distributed asymmetrically across the macronuclear envelope during amitosis. At the lower level of inducible expression, only Ran1T25N showed a significant decreasing effect on T. thermophila reproduction, macronuclear amitosis and cytokinesis. At the higher level of inducible expression, Ran1WT/Q70L/T25N inhibited T. thermophila reproduction, macronuclear amitosis and cytokinesis, and the inhibitive effect of Ran1T25N was the most significant. The inducible expression of Ran1WT/Q70L/T25N led to defects in amitosis and cytokinesis with abnormal cytoplasmic microtubule assembly. These results further confirmed the regulatory function of Ran1 on amitosis and suggested a novel role of Ran1 in cytokinesis and the alignment of cytoplasmic microtubules in T. thermophila.


Assuntos
Citocinese , Guanosina Difosfato/metabolismo , Guanosina Trifosfato/metabolismo , Microtúbulos/metabolismo , Mutação , Proteínas de Protozoários/metabolismo , Tetrahymena thermophila , Proteína ran de Ligação ao GTP/metabolismo , Microtúbulos/patologia , Mitose , Proteínas de Protozoários/genética , Tetrahymena thermophila/citologia , Tetrahymena thermophila/genética , Tetrahymena thermophila/metabolismo , Proteína ran de Ligação ao GTP/genética
9.
mSphere ; 4(3)2019 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-31043517

RESUMO

The early divergent protozoan parasite Trypanosoma brucei alternates between the insect vector and the mammalian hosts during its life cycle and proliferates through binary cell fission. The cell cycle control system in T. brucei differs substantially from that in its mammalian hosts and possesses distinct mitosis-cytokinesis checkpoint controls between two life cycle stages, the procyclic form and the bloodstream form. T. brucei undergoes an unusual mode of cytokinesis, which is controlled by a novel signaling cascade consisting of evolutionarily conserved protein kinases and trypanosome-specific regulatory proteins in the procyclic form. However, given the distinct mitosis-cytokinesis checkpoints between the two forms, it is unclear whether the cytokinesis regulatory pathway discovered in the procyclic form also operates in a similar manner in the bloodstream form. Here, we showed that the three regulators of cytokinesis initiation, cytokinesis initiation factor 1 (CIF1), CIF2, and CIF3, are interdependent for subcellular localization but not for protein stability as in the procyclic form. Further, we demonstrated that KLIF, a regulator of cytokinesis completion in the procyclic form, plays limited roles in cytokinesis in the bloodstream form. Finally, we showed that the cleavage furrow-localizing protein FRW1 is required for cytokinesis initiation in the bloodstream form but is nonessential for cytokinesis in the procyclic form. Together, these results identify conserved and life cycle-specific functions of cytokinesis regulators, highlighting the distinction in the regulation of cytokinesis between different life cycle stages of T. brucei IMPORTANCE The early divergent protozoan parasite Trypanosoma brucei is the causative agent of sleeping sickness in humans and nagana in cattle in sub-Saharan Africa. This parasite has a complex life cycle by alternating between the insect vector and the mammalian hosts and proliferates by binary cell fission. The control of cell division in trypanosomes appears to be distinct from that in its human host and differs substantially between two life cycle stages, the procyclic (insect) form and the bloodstream form. Cytokinesis, the final step of binary cell fission, is regulated by a novel signaling cascade consisting of two evolutionarily conserved protein kinases and a cohort of trypanosome-specific regulators in the procyclic form, but whether this signaling pathway operates in a similar manner in the bloodstream form is unclear. In this report, we performed a functional analysis of multiple cytokinesis regulators and discovered their distinct functions and regulations in the bloodstream form.


Assuntos
Citocinese , Proteínas de Protozoários/genética , Trypanosoma brucei brucei/genética , Trypanosoma brucei brucei/fisiologia , Tripanossomíase Bovina/sangue , Animais , Bovinos , Regulação da Expressão Gênica , Estágios do Ciclo de Vida , Proteínas Quinases/metabolismo , Proteínas de Protozoários/metabolismo
10.
MBio ; 10(2)2019 04 30.
Artigo em Inglês | MEDLINE | ID: mdl-31040242

RESUMO

Toxoplasma gondii is an obligate intracellular parasite that establishes a favorable environment in the host cells in which it replicates. We have previously reported that it uses MYR-dependent translocation of dense granule proteins to elicit a key set of host responses related to the cell cycle, specifically, E2F transcription factor targets, including cyclin E. We report here the identification of a novel Toxoplasma effector protein that is exported from the parasitophorous vacuole in a MYR1-dependent manner and localizes to the host's nucleus. Parasites lacking this inducer of host cyclin E (HCE1) are unable to modulate E2F transcription factor target genes and exhibit a substantial growth defect. Immunoprecipitation of HCE1 from infected host cells showed that HCE1 efficiently binds elements of the cyclin E regulatory complex, namely, DP1 and its partners E2F3 and E2F4. Expression of HCE1 in Neospora caninum, or in uninfected human foreskin fibroblasts (HFFs), showed localization of the expressed protein to the host nuclei and strong cyclin E upregulation. Thus, HCE1 is a novel effector protein that is necessary and sufficient to impact the E2F axis of transcription, resulting in co-opting of host functions to the advantage of Toxoplasma IMPORTANCE Like most Apicomplexan parasites, Toxoplasma gondii has the remarkable ability to invade and establish a replicative niche within another eukaryotic cell, in this case, any of a large number of cell types in almost any warm-blooded animals. Part of the process of establishing this niche is the export of effector proteins to co-opt host cell functions in favor of the parasite. Here we identify a novel effector protein, HCE1, that the parasites export into the nucleus of human cells, where it modulates the expression of multiple genes, including the gene encoding cyclin E, one of the most crucial proteins involved in controlling when and whether a human cell divides. We show that HCE1 works through binding to specific transcription factors, namely, E2F3, E2F4, and DP1, that normally carefully regulate these all-important pathways. This represents a new way in which these consummately efficient infectious agents co-opt the human cells that they so efficiently grow within.


Assuntos
Ciclina E/biossíntese , Regulação da Expressão Gênica , Interações Hospedeiro-Patógeno , Miosina Tipo I/metabolismo , Proteínas de Protozoários/metabolismo , Toxoplasma/fisiologia , Fatores de Virulência/metabolismo , Células Cultivadas , Fatores de Transcrição E2F/metabolismo , Fibroblastos/parasitologia , Humanos , Ligação Proteica , Transporte Proteico
11.
MBio ; 10(3)2019 05 14.
Artigo em Inglês | MEDLINE | ID: mdl-31088924

RESUMO

Trichomonas vaginalis, a prevalent sexually transmitted parasite, adheres to and induces cytolysis of human mucosal epithelial cells. We have characterized a hypothetical protein, TVAG_393390, with predicted tertiary structure similar to that of mammalian cadherin proteins involved in cell-cell adherence. TVAG_393390, renamed cadherin-like protein (CLP), contains a calcium-binding site at a position conserved in cadherins. CLP is surface localized, and its mRNA and protein levels are significantly upregulated upon parasite adherence to host cells. To test the roles of CLP and its calcium-binding dependency during host cell adherence, we first demonstrated that wild-type CLP (CLP) binds calcium with a high affinity, whereas the calcium-binding site mutant protein (CLP-mut) does not. CLP and CLP-mut constructs were then used to overexpress these proteins in T. vaginalis Parasites overexpressing CLP have ∼3.5-fold greater adherence to host cells than wild-type parasites, and this increased adherence is ablated by mutating the calcium-binding site. Additionally, competition with recombinant CLP decreased parasite binding to host cells. We also found that overexpression of CLP induced parasite aggregation which was further enhanced in the presence of calcium, whereas CLP-mut overexpression did not affect aggregation. Lastly, parasites overexpressing wild-type CLP induced killing of host cells ∼2.35-fold, whereas parasites overexpressing CLP-mut did not have this effect. These analyses describe the first parasitic CLP and demonstrate a role for this protein in mediating parasite-parasite and host-parasite interactions. T. vaginalis CLP may represent convergent evolution of a parasite protein that is functionally similar to the mammalian cell adhesion protein cadherin, which contributes to parasite pathogenesis.IMPORTANCE The adherence of pathogens to host cells is critical for colonization of the host and establishing infection. Here we identify a protein with no known function that is more abundant on the surface of parasites that are better at binding host cells. To interrogate a predicted function of this protein, we utilized bioinformatic protein prediction programs which allowed us to uncover the first cadherin-like protein (CLP) found in a parasite. Cadherin proteins are conserved metazoan proteins with central roles in cell-cell adhesion, development, and tissue structure maintenance. Functional characterization of this CLP from the unicellular parasite Trichomonas vaginalis demonstrated that the protein mediates both parasite-parasite and parasite-host adherence, which leads to an enhanced killing of host cells by T. vaginalis Our findings demonstrate the presence of CLPs in unicellular pathogens and identify a new host cell binding protein family in a human-infective parasite.


Assuntos
Caderinas/genética , Células Epiteliais/metabolismo , Proteínas de Protozoários/metabolismo , Trichomonas vaginalis/patogenicidade , Caderinas/metabolismo , Cálcio/metabolismo , Adesão Celular , Linhagem Celular , Células Epiteliais/parasitologia , Feminino , Humanos , Membrana Mucosa/citologia , Domínios Proteicos , Proteínas de Protozoários/genética , Ativação Transcricional , Regulação para Cima
12.
Parasitol Res ; 118(6): 1865-1874, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31065830

RESUMO

Acanthamoeba is a free-living pathogenic protozoan that is distributed in different environmental reservoirs, including lakes and soil. Pathogenic Acanthamoeba can cause severe human diseases, such as blinding keratitis and granulomatous encephalitis. Therefore, it is important to understand the pathogenic relationship between humans and Acanthamoeba. By comparison of systemic analysis results for Acanthamoeba isolates, we identified a novel secreted protein of Acanthamoeba, an M28 aminopeptidase (M28AP), which targets of the human innate immune defense. We investigated the molecular functions and characteristics of the M28AP protein by anti-M28 antibodies and a M28AP mutant strain generated by the CRISPR/Cas9 system. Human complement proteins such as C3b and iC3b were degraded by Acanthamoeba M28AP. We believe that M28AP is an important factor in human innate immunity. This study provides new insight for the development of more efficient medicines to treat Acanthamoeba infection.


Assuntos
Acanthamoeba/metabolismo , Aminopeptidases/imunologia , Aminopeptidases/metabolismo , Complemento C3/metabolismo , Proteínas de Protozoários/imunologia , Proteínas de Protozoários/metabolismo , Acanthamoeba/isolamento & purificação , Amebíase/parasitologia , Aminopeptidases/genética , Sistemas CRISPR-Cas , Humanos , Lagos/parasitologia , Proteínas de Protozoários/genética , Solo/parasitologia
13.
mSphere ; 4(3)2019 05 08.
Artigo em Inglês | MEDLINE | ID: mdl-31068431

RESUMO

The human malaria parasite Plasmodium falciparum causes disease as it replicates within the host's erythrocytes. We have found that an erythrocyte serine hydrolase, acylpeptide hydrolase (APEH), accumulates within developing asexual parasites. Internalization of APEH was associated with a proteolytic event that reduced the size of the catalytic polypeptide from 80 to 55 kDa. A triazole urea APEH inhibitor, termed AA74-1, was employed to characterize the role of parasite-internalized APEH. In cell lysates, AA74-1 was a potent and highly selective inhibitor of both host erythrocyte and parasite-internalized APEH. When added to cultures of ring-stage parasites, AA74-1 was a poor inhibitor of replication over one asexual replication cycle; however, its potency increased dramatically after a second cycle. This enhancement of potency was not abrogated by the addition of exogenous isopentenyl pyrophosphate, the sole essential product of apicoplast metabolism. High-potency inhibition of parasite growth could be effected by adding AA74-1 to schizont-stage parasites, which resulted in parasite death at the early trophozoite stage of the ensuing replication cycle. Analysis of APEH inhibition in intact cultured cells revealed that host erythrocyte APEH, but not the parasite-internalized APEH pool, was inhibited by exogenous AA74-1. Our data support a model for the mode of parasiticidal activity of AA74-1 whereby sustained inactivation of host erythrocyte APEH is required prior to merozoite invasion and during parasite asexual development. Together, these findings provide evidence for an essential catalytic role for parasite-internalized APEH.IMPORTANCE Nearly half a million deaths were attributed to malaria in 2017. Protozoan parasites of the genus Plasmodium cause disease in humans while replicating asexually within the host's erythrocytes, with P. falciparum responsible for most of the mortality. Understanding how Plasmodium spp. have adapted to their unique host erythrocyte environment is important for developing malaria control strategies. Here, we demonstrate that P. falciparum coopts a host erythrocyte serine hydrolase termed acylpeptide hydrolase. By showing that the parasite requires acylpeptide hydrolase activity for replication, we expand our knowledge of host cell factors that contribute to robust parasite growth.


Assuntos
Eritrócitos/enzimologia , Eritrócitos/parasitologia , Interações Hospedeiro-Parasita , Peptídeo Hidrolases/metabolismo , Plasmodium falciparum/fisiologia , Reprodução Assexuada , Células Cultivadas , Humanos , Malária Falciparum/parasitologia , Plasmodium falciparum/crescimento & desenvolvimento , Proteínas de Protozoários/metabolismo
14.
Plant Sci ; 284: 117-126, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31084864

RESUMO

Previously, we showed that transplastomic tobacco plants expressing the LiHsp83-SAG1 fusion protein displayed a chlorotic phenotype and growth retardation, while plants expressing the SAG1 and GRA4 antigens alone did not. We conducted a comprehensive examination of the metabolic and photosynthetic parameters that could be affecting the normal growth of LiHsp83-SAG1 plants in order to understand the origin of these pleiotropic effects. These plants presented all photosynthetic pigments and parameters related to PSII efficiency significantly diminished. However, the expression of CHLI, RSSU and LHCa/b genes did not show significant differences between LiHsp83-SAG1 and control plants. Total protein, starch, and soluble sugar contents were also greatly reduced in LiHsp83-SAG1 plants. Since Hsp90 s are constitutively expressed at much higher concentrations at high temperatures, we tested if the fitness of LiHsp83-SAG1 over-expressing LiHsp83 would improve after heat treatment. LiHsp83-SAG1 plants showed an important alleviation of their phenotype and an evident recovery of the PSII function. As far as we know, this is the first report where it is demonstrated that a transplastomic line performs much better at higher temperatures. Finally, we detected that LiHsp83-SAG1 protein could be binding to key photosynthesis-related proteins at 37 °C. Our results suggest that the excess of this molecular chaperone could benefit the plant in a possible heat shock and prevent the expected denaturation of proteins. However, the LiHsp83-SAG1 protein content was weakly decreased in heat-treated plants. Therefore, we cannot rule out that the alleviation observed at 37 °C may be partially due to a reduction of the levels of the recombinant protein.


Assuntos
Antígenos de Protozoários/metabolismo , Proteínas de Choque Térmico/metabolismo , Leishmania infantum/metabolismo , Fotossíntese , Plantas Geneticamente Modificadas/metabolismo , Proteínas de Protozoários/metabolismo , Proteínas Recombinantes de Fusão/metabolismo , Toxoplasma/metabolismo , Clorofila/metabolismo , Cromatografia Gasosa-Espectrometria de Massas , Perfilação da Expressão Gênica , Temperatura Alta , Imunoprecipitação , Folhas de Planta/metabolismo , Plantas Geneticamente Modificadas/crescimento & desenvolvimento , Plantas Geneticamente Modificadas/parasitologia , Tabaco
15.
MBio ; 10(3)2019 05 07.
Artigo em Inglês | MEDLINE | ID: mdl-31064825

RESUMO

The mitochondrial Ca2+ uptake in trypanosomatids, which belong to the eukaryotic supergroup Excavata, shares biochemical characteristics with that of animals, which, together with fungi, belong to the supergroup Opisthokonta. However, the composition of the mitochondrial calcium uniporter (MCU) complex in trypanosomatids is quite peculiar, suggesting lineage-specific adaptations. In this work, we used Trypanosoma cruzi to study the role of orthologs for mitochondrial calcium uptake 1 (MICU1) and MICU2 in mitochondrial Ca2+ uptake. T. cruzi MICU1 (TcMICU1) and TcMICU2 have mitochondrial targeting signals, two canonical EF-hand calcium-binding domains, and localize to the mitochondria. Using the CRISPR/Cas9 system (i.e., clustered regularly interspaced short palindromic repeats with Cas9), we generated TcMICU1 and TcMICU2 knockout (-KO) cell lines. Ablation of either TcMICU1 or TcMICU2 showed a significantly reduced mitochondrial Ca2+ uptake in permeabilized epimastigotes without dissipation of the mitochondrial membrane potential or effects on the AMP/ATP ratio or citrate synthase activity. However, none of these proteins had a gatekeeper function at low cytosolic Ca2+ concentrations ([Ca2+]cyt), as occurs with their mammalian orthologs. TcMICU1-KO and TcMICU2-KO epimastigotes had a lower growth rate and impaired oxidative metabolism, while infective trypomastigotes have a reduced capacity to invade host cells and to replicate within them as amastigotes. The findings of this work, which is the first to study the role of MICU1 and MICU2 in organisms evolutionarily distant from animals, suggest that, although these components were probably present in the last eukaryotic common ancestor (LECA), they developed different roles during evolution of different eukaryotic supergroups. The work also provides new insights into the adaptations of trypanosomatids to their particular life styles.IMPORTANCE Trypanosoma cruzi is the etiologic agent of Chagas disease and belongs to the early-branching eukaryotic supergroup Excavata. Its mitochondrial calcium uniporter (MCU) subunit shares similarity with the animal ortholog that was important to discover its encoding gene. In animal cells, the MICU1 and MICU2 proteins act as Ca2+ sensors and gatekeepers of the MCU, preventing Ca2+ uptake under resting conditions and favoring it at high cytosolic Ca2+ concentrations ([Ca2+]cyt). Using the CRISPR/Cas9 technique, we generated TcMICU1 and TcMICU2 knockout cell lines and showed that MICU1 and -2 do not act as gatekeepers at low [Ca2+]cyt but are essential for normal growth, host cell invasion, and intracellular replication, revealing lineage-specific adaptations.


Assuntos
Proteínas de Ligação ao Cálcio/metabolismo , Cálcio/metabolismo , Mitocôndrias/metabolismo , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Proteínas de Protozoários/metabolismo , Trypanosoma cruzi/genética , Adaptação Fisiológica , Transporte Biológico , Sistemas CRISPR-Cas , Proteínas de Ligação ao Cálcio/genética , Proteínas de Transporte de Cátions , Citosol/química , Citosol/metabolismo , Técnicas de Inativação de Genes , Humanos , Proteínas de Transporte da Membrana Mitocondrial/genética , Proteínas de Protozoários/genética , Trypanosoma cruzi/patogenicidade
16.
Parasit Vectors ; 12(1): 227, 2019 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-31088539

RESUMO

BACKGROUND: Giardia lamblia, a protozoan pathogen causing diarrheal outbreaks, has characteristic cytoskeletal structures including eight flagella, a median body and a ventral disc. Gamma-giardin is a unique component protein of the cytoskeleton of this protozoan. RESULTS: Through comparative proteomic analysis between different stages of the cell cycle, G. lamblia γ-giardin (Glγ-giardin) was identified as an upregulated protein in the G2-phase. Increased Glγ-giardin expression in G2 was confirmed by western blot and real-time polymerase chain reaction analyses. Knockdown of this protein using a morpholino affected the formation of ventral discs, especially the microribbons of the discs, but exerted little effect on the binding ability of G. lamblia. The number of cells with four nuclei was increased in Glγ-giardin-knockdown cells. Expression of Glγ-giardin was decreased during encystation, in contrast with the G2-phase. CONCLUSIONS: Knockdown experiments demonstrated that Glγ-giardin is a component of the trilaminar structure of the ventral disc. Expression of Glγ-giardin is induced in the G2-phase prior to active cell division, whereas its expression decreases during encystation, a dormant stage of G. lamblia.


Assuntos
Proteínas do Citoesqueleto/genética , Fase G2/genética , Giardia lamblia/citologia , Giardia lamblia/crescimento & desenvolvimento , Proteínas de Protozoários/genética , Proteínas do Citoesqueleto/metabolismo , Citoesqueleto/química , Citoesqueleto/genética , Técnicas de Silenciamento de Genes , Encistamento de Parasitas , Proteômica , Proteínas de Protozoários/metabolismo , Alinhamento de Sequência , Regulação para Cima
17.
Nat Microbiol ; 4(7): 1208-1220, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31036909

RESUMO

The protozoan parasite Toxoplasma gondii has co-evolved with its homeothermic hosts (humans included) strategies that drive its quasi-asymptomatic persistence in hosts, hence optimizing the chance of transmission to new hosts. Persistence, which starts with a small subset of parasites that escape host immune killing and colonize the so-called immune privileged tissues where they differentiate into a low replicating stage, is driven by the interleukin 12 (IL-12)-interferon-γ (IFN-γ) axis. Recent characterization of a family of Toxoplasma effectors that are delivered into the host cell, in which they rewire the host cell gene expression, has allowed the identification of regulators of the IL-12-IFN-γ axis, including repressors. We now report on the dense granule-resident effector, called TEEGR (Toxoplasma E2F4-associated EZH2-inducing gene regulator) that counteracts the nuclear factor-κB (NF-κB) signalling pathway. Once exported into the host cell, TEEGR ends up in the nucleus where it not only complexes with the E2F3 and E2F4 host transcription factors to induce gene expression, but also promotes shaping of a non-permissive chromatin through its capacity to switch on EZH2. Remarkably, EZH2 fosters the epigenetic silencing of a subset of NF-κB-regulated cytokines, thereby strongly contributing to the host immune equilibrium that influences the host immune response and promotes parasite persistence in mice.


Assuntos
Proteína Potenciadora do Homólogo 2 de Zeste/metabolismo , NF-kappa B/metabolismo , Proteínas de Protozoários/metabolismo , Transdução de Sinais/genética , Toxoplasma/fisiologia , Animais , Linhagem Celular , Núcleo Celular/metabolismo , Citocinas/metabolismo , Fatores de Transcrição E2F/genética , Fatores de Transcrição E2F/metabolismo , Proteína Potenciadora do Homólogo 2 de Zeste/genética , Expressão Gênica , Regulação da Expressão Gênica , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Mutação , Carga Parasitária , Regiões Promotoras Genéticas , Multimerização Proteica , Proteínas de Protozoários/genética , Toxoplasma/genética , Toxoplasma/imunologia , Toxoplasmose/metabolismo , Toxoplasmose/parasitologia
18.
Genes Cells ; 24(6): 422-435, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31002205

RESUMO

Dictyostelium STATa is a homologue of metazoan signal transducers and activators of transcription (STATs) and is important for morphogenesis. STATa is activated by phosphorylation on Tyr702 when cells are exposed to extracellular cAMP. Although two tyrosine kinase-like (TKL) proteins, Pyk2 and Pyk3, have been definitively identified as STATc kinases, no kinase is known for STATa activation. Based on homology to the previously identified tyrosine-selective TKLs, we identified DrkA, a member of the TKL family and the Dictyostelium receptor-like kinase (DRK) subfamily, as a candidate STATa kinase. The drkA gene is almost exclusively expressed in prestalk A (pstA) cells, where STATa is activated. Transient over-expression of DrkA increased STATa phosphorylation, although over-expression of the protein causes a severe growth defect and cell death. Furthermore, recombinant DrkA protein is auto-phosphorylated on tyrosine and threonine residues, and an in vitro kinase assay shows that DrkA can phosphorylate STATa on Tyr702 in a STATa-SH2 (phosphotyrosine binding) domain-dependent manner. These observations strongly suggest that DrkA is one of the key regulators of STATa tyrosine phosphorylation and is consistent with it being the kinase that directly activates STATa.


Assuntos
Dictyostelium/metabolismo , Proteínas de Protozoários/metabolismo , Fatores de Transcrição STAT/metabolismo , Animais , Dictyostelium/citologia , Dictyostelium/genética , Morfogênese , Mutação , Fosforilação , Proteínas Quinases/metabolismo , Proteínas Tirosina Quinases/metabolismo , Proteínas de Protozoários/genética , Proteínas de Protozoários/fisiologia , Fatores de Transcrição STAT/genética , Fatores de Transcrição STAT/fisiologia , Tirosina/metabolismo
19.
PLoS Pathog ; 15(4): e1007512, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30947298

RESUMO

The single mitochondrion of apicomplexan protozoa is thought to be critical for all stages of the life cycle, and is a validated drug target against these important human and veterinary parasites. In contrast to other eukaryotes, replication of the mitochondrion is tightly linked to the cell cycle. A key step in mitochondrial segregation is the fission event, which in many eukaryotes occurs by the action of dynamins constricting the outer membrane of the mitochondria from the cytosolic face. To date, none of the components of the apicomplexan fission machinery have been identified and validated. We identify here a highly divergent, dynamin-related protein (TgDrpC), conserved in apicomplexans as essential for mitochondrial biogenesis and potentially for fission in Toxoplasma gondii. We show that TgDrpC is found adjacent to the mitochondrion, and is localised both at its periphery and at its basal part, where fission is expected to occur. We demonstrate that depletion or dominant negative expression of TgDrpC results in interconnected mitochondria and ultimately in drastic changes in mitochondrial morphology, as well as in parasite death. Intriguingly, we find that the canonical adaptor TgFis1 is not required for mitochondrial fission. The identification of an Apicomplexa-specific enzyme required for mitochondrial biogenesis and essential for parasite growth highlights parasite adaptation. This work paves the way for future drug development targeting TgDrpC, and for the analysis of additional partners involved in this crucial step of apicomplexan multiplication.


Assuntos
Dinaminas/metabolismo , Fibroblastos/metabolismo , Dinâmica Mitocondrial , Proteínas de Protozoários/metabolismo , Toxoplasma/fisiologia , Toxoplasmose/metabolismo , Células Cultivadas , Dinaminas/genética , Fibroblastos/citologia , Fibroblastos/parasitologia , Humanos , Proteínas de Protozoários/genética , Toxoplasmose/genética , Toxoplasmose/parasitologia
20.
mSphere ; 4(2)2019 04 03.
Artigo em Inglês | MEDLINE | ID: mdl-30944211

RESUMO

Inorganic pyrophosphate (PPi) is a by-product of biosynthetic reactions and has bioenergetic and regulatory roles in a variety of cells. Here we show that PPi and other pyrophosphate-containing compounds, including polyphosphate (polyP), can stimulate sodium-dependent depolarization of the membrane potential and Pi conductance in Xenopus oocytes expressing a Saccharomyces cerevisiae or Trypanosoma brucei Na+/Pi symporter. PPi is not taken up by Xenopus oocytes, and deletion of the TbPho91 SPX domain abolished its depolarizing effect. PPi generated outward currents in Na+/Pi-loaded giant vacuoles prepared from wild-type or pho91Δ yeast strains expressing TbPHO91 but not from the pho91Δ strains. Our results suggest that PPi, at physiological concentrations, can function as a signaling molecule releasing Pi from S. cerevisiae vacuoles and T. brucei acidocalcisomes.IMPORTANCE Acidocalcisomes, first described in trypanosomes and known to be present in a variety of cells, have similarities with S. cerevisiae vacuoles in their structure and composition. Both organelles share a Na+/Pi symporter involved in Pi release to the cytosol, where it is needed for biosynthetic reactions. Here we show that PPi, at physiological cytosolic concentrations, stimulates the symporter expressed in either Xenopus oocytes or yeast vacuoles via its SPX domain, revealing a signaling role of this molecule.


Assuntos
Saccharomyces cerevisiae/metabolismo , Proteínas Cotransportadoras de Sódio-Fosfato/metabolismo , Simportadores/genética , Trypanosoma brucei brucei/metabolismo , Vacúolos/metabolismo , Animais , Potenciais da Membrana , Oócitos/metabolismo , Fosfatos/metabolismo , Proteínas de Protozoários/genética , Proteínas de Protozoários/metabolismo , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Transdução de Sinais , Sódio/metabolismo , Proteínas Cotransportadoras de Sódio-Fosfato/genética , Trypanosoma brucei brucei/genética , Xenopus/metabolismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA