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Carvalho-Kelly LF, Freitas-Mesquita AL, Ferreira Pralon C, de Souza-Maciel E, Meyer-Fernandes JR. Identification and characterization of an ectophosphatase activity involved in Acanthamoeba castellanii adhesion to host cells. Eur J Protistol 2023; 91:126026. [PMID: 37871554 DOI: 10.1016/j.ejop.2023.126026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 10/06/2023] [Accepted: 10/11/2023] [Indexed: 10/25/2023]
Abstract
Acanthamoeba castellanii is a free-living amoeba and an opportunistic pathogen for humans that can cause encephalitis and, more commonly, Acanthamoeba keratitis. During its life cycle, A. castellanii may present as proliferative and infective trophozoites or resistant cysts. The adhesion of trophozoites to host cells is a key first step in the pathogenesis of infection. A major virulence protein of Acanthamoeba is a mannose-binding protein (MBP) that mediates the adhesion of amoebae to cell surfaces. Ectophosphatases are ecto-enzymes that can dephosphorylate extracellular substrates and have already been described in several microorganisms. Regarding their physiological roles, there is consistent evidence that ectophosphatase activities play an important role in parasite-host interactions. In the present work, we identified and biochemically characterized the ectophosphatase activity of A. castellanii. The ectophosphatase activity is acidic, stimulated by magnesium, cobalt and nickel, and presents the following apparent kinetic parameters: Km = 2.12 ± 0.54 mM p-NPP and Vmax = 26.12 ± 2.53 nmol p-NP × h-1 × 10-6 cells. We observed that sodium orthovanadate, ammonium molybdate, sodium fluoride, and inorganic phosphate are able to inhibit ectophosphatase activity. Comparing the two stages of the A. castellanii lifecycle, ectophosphatase activity is significantly higher in trophozoites than in cysts. The ectophosphatase activity is stimulated by mannose residues and is significantly increased when trophozoites interact with LLC-MK2 cells. The inhibition of ectophosphatase by pretreatment with sodium orthovanadate also inhibits the adhesion of trophozoites to epithelial cells. These results allow us to conclude that the ectophosphatase activity of A. castellanii is somehow important for the adhesion of trophozoites to their host cells. According to our data, we believe that the activation of MBP by mannose residues triggers the stimulation of ectophosphatase activity to facilitate the adhesion process.
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Affiliation(s)
| | | | - Clara Ferreira Pralon
- Instituto de Bioquímica Médica Leopoldo de Meis (IBqM), UFRJ, Rio de Janeiro, RJ, Brazil
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Takamiya NT, Rogerio LA, Torres C, Leonel JAF, Vioti G, de Sousa Oliveira TMF, Valeriano KC, Porcino GN, de Miranda Santos IKF, Costa CHN, Costa DL, Ferreira TS, Gurgel-Gonçalves R, da Silva JS, Teixeira FR, De Almeida RP, Ribeiro JMC, Maruyama SR. Parasite Detection in Visceral Leishmaniasis Samples by Dye-Based qPCR Using New Gene Targets of Leishmania infantum and Crithidia. Trop Med Infect Dis 2023; 8:405. [PMID: 37624343 PMCID: PMC10457869 DOI: 10.3390/tropicalmed8080405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 07/26/2023] [Accepted: 07/31/2023] [Indexed: 08/26/2023] Open
Abstract
Visceral leishmaniasis (VL) is a neglected disease considered a serious public health problem, especially in endemic countries. Several studies have discovered monoxenous trypanosomatids (Leptomonas and Crithidia) in patients with VL. In different situations of leishmaniasis, investigations have examined cases of co-infection between Leishmania spp. and Crithidia spp. These coinfections have been observed in a wide range of vertebrate hosts, indicating that they are not rare. Diagnostic techniques require improvements and more robust tools to accurately detect the causative agent of VL. This study aimed to develop a real-time quantitative dye-based PCR (qPCR) assay capable of distinguishing Leishmania infantum from Crithidia-related species and to estimate the parasite load in samples of VL from humans and animals. The primer LinJ31_2420 targets an exclusive phosphatase of L. infantum; the primer Catalase_LVH60-12060_1F targets the catalase gene of Crithidia. Therefore, primers were designed to detect L. infantum and Crithidia sp. LVH60A (a novel trypanosomatid isolated from VL patients in Brazil), in samples related to VL. These primers were considered species-specific, based on sequence analysis using genome data retrieved from the TriTryp database and the genome assembling of Crithidia sp. LVH60A strain, in addition to experimental and clinical data presented herein. This novel qPCR assay was highly accurate in identifying and quantifying L. infantum and Crithidia sp. LVH60A in samples obtained experimentally (in vitro and in vivo) or collected from hosts (humans, dogs, cats, and vectors). Importantly, the screening of 62 cultured isolates from VL patients using these primers surprisingly revealed that 51 parasite cultures were PCR+ for Crithidia sp. In addition, qPCR assays identified the co-infection of L. infantum with Crithidia sp. LVH60A in two new VL cases in Brazil, confirming the suspicion of co-infection in a previously reported case of fatal VL. We believe that the species-specific genes targeted in this study can be helpful for the molecular diagnosis of VL, as well as for elucidating suspected co-infections with monoxenous-like trypanosomatids, which is a neglected fact of a neglected disease.
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Affiliation(s)
- Nayore Tamie Takamiya
- Department of Genetics and Evolution, Center for Biological Sciences and Health, Federal University of São Carlos (UFSCar), São Carlos 13565-905, SP, Brazil; (N.T.T.); (F.R.T.)
| | - Luana Aparecida Rogerio
- Department of Genetics and Evolution, Center for Biological Sciences and Health, Federal University of São Carlos (UFSCar), São Carlos 13565-905, SP, Brazil; (N.T.T.); (F.R.T.)
| | - Caroline Torres
- Department of Genetics and Evolution, Center for Biological Sciences and Health, Federal University of São Carlos (UFSCar), São Carlos 13565-905, SP, Brazil; (N.T.T.); (F.R.T.)
| | - João Augusto Franco Leonel
- Post-Graduate Program in Experimental Epidemiology Applied to Zoonoses at the Faculty of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo 05508-270, SP, Brazil
| | - Geovanna Vioti
- Post-Graduate Program in Experimental Epidemiology Applied to Zoonoses at the Faculty of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo 05508-270, SP, Brazil
| | - Tricia Maria Ferreira de Sousa Oliveira
- Post-Graduate Program in Experimental Epidemiology Applied to Zoonoses at the Faculty of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo 05508-270, SP, Brazil
- Department of Veterinary Medicine, Faculty of Animal Science and Food Engineering, University of São Paulo, Pirassununga 13635-900, SP, Brazil
| | - Karoline Camila Valeriano
- Ribeirão Preto Medical School, University of São Paulo, FMRP-USP, Ribeirão Preto 14049-900, SP, Brazil
| | | | | | - Carlos H. N. Costa
- Natan Portela Institute of Tropical Diseases, Teresina 64002-510, PI, Brazil
| | | | - Tauana Sousa Ferreira
- Laboratory of Medical Parasitology and Vector Biology, Faculty of Medicine, University of Brasília, Brasília 70910-900, DF, Brazil
| | - Rodrigo Gurgel-Gonçalves
- Laboratory of Medical Parasitology and Vector Biology, Faculty of Medicine, University of Brasília, Brasília 70910-900, DF, Brazil
| | - João Santana da Silva
- Fiocruz-Bi-Institutional Translational Medicine Project, Oswaldo Cruz Foundation, Ribeirão Preto 14040-900, SP, Brazil
| | - Felipe Roberti Teixeira
- Department of Genetics and Evolution, Center for Biological Sciences and Health, Federal University of São Carlos (UFSCar), São Carlos 13565-905, SP, Brazil; (N.T.T.); (F.R.T.)
| | - Roque Pacheco De Almeida
- Department of Medicine, Center for Biology and Health Sciences, Federal University of Sergipe (UFS), Aracaju 49060-108, SE, Brazil
| | - José M. C. Ribeiro
- National Institute of Allergy and Infectious Diseases, National Institutes of Health, NIH/NIAID, Rockville, MD 20892, USA
| | - Sandra Regina Maruyama
- Department of Genetics and Evolution, Center for Biological Sciences and Health, Federal University of São Carlos (UFSCar), São Carlos 13565-905, SP, Brazil; (N.T.T.); (F.R.T.)
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Freitas-Mesquita AL, Carvalho-Kelly LF, Majerowicz TSS, Meyer-Fernandes JR. Euglena gracilis: Biochemical properties of a membrane bound ecto-phosphatase activity modulated by fluoroaluminate complexes and different trophic conditions. Eur J Protistol 2023; 90:126010. [PMID: 37540916 DOI: 10.1016/j.ejop.2023.126010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 07/05/2023] [Accepted: 07/17/2023] [Indexed: 08/06/2023]
Abstract
The ecto-phosphatases belong to a group of enzymes closely associated with the cell surface that has its catalytic site facing the extracellular environment, where different phosphorylated substrates can be hydrolyzed. In the present work, we biochemically characterized the ecto-phosphatase activity of the freshwater microalgae Euglena gracilis, a model microorganism, ubiquitously distributed and resistant to several environmental stressors. The ecto-phosphatase activity is acidic, stimulated by copper and presents the following apparent kinetic parameters: Km = 2.52 ± 0.12 mM p-NPP and Vmax = 3.62 ± 0.06 nmol p-NP × h-1 × 106 cells. We observed that zinc, orthovanadate, molybdate, fluoride, and inorganic phosphate inhibit the ecto-phosphatase activity with different magnitudes. Fluoroaluminate complexes are also inhibitors of this ecto-phosphatase activity. They can be formed in the enzyme reaction conditions and are likely to occur in a natural environment where E. gracilis can be found. The ecto-phosphatase activity is constant through the culture growth phases and is negatively modulated after continuous subculturing in the dark when a shift from phototrophic to the heterotrophic metabolism is likely. The analysis of those biochemical parameters may contribute to understanding the role of E. gracilis ecto-phosphatase activity in natural environments.
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Affiliation(s)
- Anita Leocadio Freitas-Mesquita
- Instituto de Bioquímica Médica Leopoldo de Meis, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, 21941-590 Rio de Janeiro, RJ, Brazil; Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem, 21941-590 Rio de Janeiro, RJ, Brazil.
| | - Luiz Fernando Carvalho-Kelly
- Instituto de Bioquímica Médica Leopoldo de Meis, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, 21941-590 Rio de Janeiro, RJ, Brazil; Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem, 21941-590 Rio de Janeiro, RJ, Brazil
| | - Thaís Souza Silveira Majerowicz
- Instituto de Bioquímica Médica Leopoldo de Meis, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, 21941-590 Rio de Janeiro, RJ, Brazil; Instituto Federal de Educação, Ciência e Tecnologia do Rio de Janeiro, Rua Senador Furtado, 121. Maracanã, Rio de Janeiro, RJ 20270-021, Brazil
| | - José Roberto Meyer-Fernandes
- Instituto de Bioquímica Médica Leopoldo de Meis, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, 21941-590 Rio de Janeiro, RJ, Brazil; Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem, 21941-590 Rio de Janeiro, RJ, Brazil.
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Lacerda-Abreu MA, Dick CF, Meyer-Fernandes JR. The Role of Inorganic Phosphate Transporters in Highly Proliferative Cells: From Protozoan Parasites to Cancer Cells. MEMBRANES 2022; 13:42. [PMID: 36676849 PMCID: PMC9860751 DOI: 10.3390/membranes13010042] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 12/01/2022] [Accepted: 12/26/2022] [Indexed: 06/17/2023]
Abstract
In addition to their standard inorganic phosphate (Pi) nutritional function, Pi transporters have additional roles in several cells, including Pi sensing (the so-called transceptor) and a crucial role in Pi metabolism, where they control several phenotypes, such as virulence in pathogens and tumour aggressiveness in cancer cells. Thus, intracellular Pi concentration should be tightly regulated by the fine control of intake and storage in organelles. Pi transporters are classified into two groups: the Pi transporter (PiT) family, also known as the Pi:Na+ symporter family; and the Pi:H+ symporter (PHS) family. Highly proliferative cells, such as protozoan parasites and cancer cells, rely on aerobic glycolysis to support the rapid generation of biomass, which is equated with the well-known Warburg effect in cancer cells. In protozoan parasite cells, Pi transporters are strongly associated with cell proliferation, possibly through their action as intracellular Pi suppliers for glyceraldehyde-3-phosphate dehydrogenase (GAPDH) activity. Similarly, the growth rate hypothesis (GRH) proposes that the high Pi demands of tumours when achieving accelerated proliferation are mainly due to increased allocation to P-rich nucleic acids. The purpose of this review was to highlight recent advances in understanding the role of Pi transporters in unicellular eukaryotes and tumorigenic cells, correlating these roles with metabolism in these cells.
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Affiliation(s)
- Marco Antonio Lacerda-Abreu
- Leopoldo de Meis Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro 21941-902, Brazil
| | - Claudia Fernanda Dick
- National Center of Structural Biology and Bioimaging (CENABIO), Federal University of Rio de Janeiro, Rio de Janeiro 21941-902, Brazil
| | - José Roberto Meyer-Fernandes
- Leopoldo de Meis Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro 21941-902, Brazil
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Freitas-Mesquita AL, Dos-Santos ALA, Meyer-Fernandes JR. Involvement of Leishmania Phosphatases in Parasite Biology and Pathogeny. Front Cell Infect Microbiol 2021; 11:633146. [PMID: 33968798 PMCID: PMC8100340 DOI: 10.3389/fcimb.2021.633146] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 04/06/2021] [Indexed: 01/01/2023] Open
Abstract
In the Leishmania lifecycle, the motile promastigote form is transmitted from the sand fly vector to a mammalian host during a blood meal. Inside vertebrate host macrophages, the parasites can differentiate into the amastigote form and multiply, causing leishmaniasis, one of the most significant neglected tropical diseases. Leishmania parasites face different conditions throughout their development inside sand flies. Once in the mammalian host, the parasites have to overcome the microbicide repertoire of the cells of the immune system to successfully establish the infection. In this context, the expression of protein phosphatases is of particular interest. Several members of the serine/threonine-specific protein phosphatase (STP), protein tyrosine phosphatase (PTP), and histidine acid phosphatase (HAcP) families have been described in different Leishmania species. Although their physiological roles have not been fully elucidated, many studies suggest they have an involvement with parasite biology and pathogeny. Phosphatases play a role in adaptation to nutrient starvation during parasite passage through the sand fly midgut. They are also important to parasite virulence, mainly due to the modulation of host cytokine production and impairment of the microbiocidal potential of macrophages. Furthermore, recent whole-genome expression analyses have shown that different phosphatases are upregulated in metacyclic promastigotes, the infective form of the mammalian host. Leishmania phosphatases are also upregulated in drug-resistant strains, probably due to the increase in drug efflux related to the activation of ABC transporters. Throughout this review, we will describe the physiological roles that have been attributed to Leishmania endogenous phosphatases, including their involvement in the adaptation, survival, and proliferation of the parasites inside their hosts.
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Affiliation(s)
- Anita Leocadio Freitas-Mesquita
- Instituto de Bioquímica Médica Leopoldo De Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.,Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - André Luiz Araújo Dos-Santos
- Instituto de Bioquímica Médica Leopoldo De Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.,Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - José Roberto Meyer-Fernandes
- Instituto de Bioquímica Médica Leopoldo De Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.,Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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Dos-Santos ALA, Dick CF, Lopes LR, Rocco-Machado N, Muzi-Filho H, Freitas-Mesquita AL, Paes-Vieira L, Vieyra A, Meyer-Fernandes JR. Tartrate-resistant phosphatase type 5 in Trypanosoma cruzi is important for resistance to oxidative stress promoted by hydrogen peroxide. Exp Parasitol 2019; 205:107748. [PMID: 31442453 DOI: 10.1016/j.exppara.2019.107748] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 08/01/2019] [Accepted: 08/19/2019] [Indexed: 11/28/2022]
Abstract
Trypanosoma cruzi (the causative agent of Chagas disease) presents a complex life cycle that involves adaptations in vertebrate and invertebrate hosts. As a protozoan parasite of hematophagous insects and mammalian hosts, T. cruzi is exposed to reactive oxygen species (ROS). To investigate the functionality of T. cruzi tartrate-resistant acid phosphatase type 5 (TcACP5), we cloned, superexpressed and purified the enzyme. Purified TcACP5 exhibited a Vmax and apparent Km for pNPP hydrolysis of 7.7 ± 0.2 nmol pNP × μg-1 × h-1 and 169.3 ± 22.6 μM, respectively. The pH dependence was characterized by sharp maximal activity at pH 5.0, and inhibition assays demonstrated its sensitivity to acid phosphatase inhibitors. Similar activities were obtained with saturating concentrations of P-Ser and P-Thr as substrates. The enzyme metabolizes hydrogen peroxide (H2O2) in vitro, and parasites superexpressing this enzyme were more resistant to oxidative stress promoted by H2O2. Taken together, these results suggest that TcACP5 plays a central role in phosphoryl transfer and redox reactions.
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Affiliation(s)
- André L A Dos-Santos
- Leopoldo De Meis Medical Biochemistry Institute, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil; National Institute of Science and Technology for Structural Biology and Bioimaging (INBEB), Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Claudia F Dick
- Leopoldo De Meis Medical Biochemistry Institute, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil; Carlos Chagas Filho Biophysics Institute, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil; National Institute of Science and Technology for Structural Biology and Bioimaging (INBEB), Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Leandro R Lopes
- Leopoldo De Meis Medical Biochemistry Institute, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil; Paulo de Góes Microbiology Institute, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil; National Institute of Science and Technology for Structural Biology and Bioimaging (INBEB), Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Nathália Rocco-Machado
- Leopoldo De Meis Medical Biochemistry Institute, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil; National Institute of Science and Technology for Structural Biology and Bioimaging (INBEB), Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Humberto Muzi-Filho
- Carlos Chagas Filho Biophysics Institute, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil; National Center for Structural Biology and Bioimaging (CENABIO), Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Anita L Freitas-Mesquita
- Leopoldo De Meis Medical Biochemistry Institute, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil; National Institute of Science and Technology for Structural Biology and Bioimaging (INBEB), Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Lisvane Paes-Vieira
- Leopoldo De Meis Medical Biochemistry Institute, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil; National Institute of Science and Technology for Structural Biology and Bioimaging (INBEB), Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Adalberto Vieyra
- Carlos Chagas Filho Biophysics Institute, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil; National Center for Structural Biology and Bioimaging (CENABIO), Federal University of Rio de Janeiro, Rio de Janeiro, Brazil; Graduate Program in Translational Biomedicine, Grande Rio University, Duque de Caxias, Brazil
| | - José Roberto Meyer-Fernandes
- Leopoldo De Meis Medical Biochemistry Institute, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil; National Institute of Science and Technology for Structural Biology and Bioimaging (INBEB), Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
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Arora K, Rai AK. Dependence of Leishmania parasite on host derived ATP: an overview of extracellular nucleotide metabolism in parasite. J Parasit Dis 2019; 43:1-13. [PMID: 30956439 PMCID: PMC6423245 DOI: 10.1007/s12639-018-1061-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2018] [Accepted: 11/24/2018] [Indexed: 12/29/2022] Open
Affiliation(s)
- Kashika Arora
- Department of Biotechnology, Motilal Nehru National Institute of Technology (MNNIT) Allahabad, Allahabad, 211004 U.P. India
- Present Address: Biomedical Research Center, Ghent University Global Campus, Incheon, 21985 South Korea
| | - Ambak Kumar Rai
- Department of Biotechnology, Motilal Nehru National Institute of Technology (MNNIT) Allahabad, Allahabad, 211004 U.P. India
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Soulat D, Bogdan C. Function of Macrophage and Parasite Phosphatases in Leishmaniasis. Front Immunol 2017; 8:1838. [PMID: 29312331 PMCID: PMC5743797 DOI: 10.3389/fimmu.2017.01838] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2017] [Accepted: 12/05/2017] [Indexed: 01/23/2023] Open
Abstract
The kinetoplastid protozoan parasites belonging to the genus Leishmania are the causative agents of different clinical forms of leishmaniasis, a vector-borne infectious disease with worldwide prevalence. The protective host immune response against Leishmania parasites relies on myeloid cells such as dendritic cells and macrophages in which upon stimulation by cytokines (e.g., interferon-γ) a complex network of signaling pathways is switched on leading to strong antimicrobial activities directed against the intracellular parasite stage. The regulation of these pathways classically depends on post-translational modifications of proteins, with phosphorylation events playing a cardinal role. Leishmania parasites deactivate their phagocytic host cells by inducing specific mammalian phosphatases that are capable to impede signaling. On the other hand, there is now also evidence that Leishmania spp. themselves express phosphatases that might target host cell molecules and thereby facilitate the intracellular survival of the parasite. This review will present an overview on the modulation of host phosphatases by Leishmania parasites as well as on the known families of Leishmania phosphatases and their possible function as virulence factors. A more detailed understanding of the role of phosphatases in Leishmania–host cell interactions might open new avenues for the treatment of non-healing, progressive forms of leishmaniasis.
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Affiliation(s)
- Didier Soulat
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Erlangen, Germany.,Medical Immunology Campus Erlangen, Interdisciplinary Center of the FAU, Erlangen, Germany
| | - Christian Bogdan
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Erlangen, Germany.,Medical Immunology Campus Erlangen, Interdisciplinary Center of the FAU, Erlangen, Germany
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Deep Insight into the Phosphatomes of Parasitic Protozoa and a Web Resource ProtozPhosDB. PLoS One 2016; 11:e0167594. [PMID: 27930683 PMCID: PMC5145157 DOI: 10.1371/journal.pone.0167594] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 11/16/2016] [Indexed: 11/19/2022] Open
Abstract
Phosphorylation dynamically regulates the function of proteins by maintaining a balance between protein kinase and phosphatase activity. A comprehensive understanding of the role phosphatases in cellular signaling is lacking in case of protozoans of medical and veterinary importance worldwide. The drugs used to treat protozoal diseases have many undesired effects and the development of resistance, highlights the need for new effective and safer antiprotozoal agents. In the present study we have analyzed phosphatomes of 15 protozoans of medical significance. We identified ~2000 phosphatases, out of which 21% are uncharacterized proteins. A significant positive correlation between phosphatome and proteome size was observed except for E. histolytica, having highest density of phosphatases irrespective of its proteome size. A difference in the number of phosphatases among different genera shows the variation in the signaling pathways they are involved in. The phosphatome of parasites is dominated by ser/thr phosphatases contrary to the vertebrate host dominated by tyrosine phosphatases. Phosphatases were widely distributed throughout the cell suggesting physiological adaptation of the parasite to regulate its host. 20% to 45% phosphatome of different protozoa consists of ectophosphatases, i.e. crucial for the survival of parasites. A database and a webserver "ProtozPhosDB" can be used to explore the phosphatomes of protozoans of medical significance.
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Singh N, Yadav S, Rathaur S. Identification and characterization of novel membrane-bound PRL protein tyrosine phosphatases from Setaria cervi, a bovine filarial parasite. Parasitol Res 2015; 114:4267-79. [PMID: 26341797 DOI: 10.1007/s00436-015-4667-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 08/06/2015] [Indexed: 11/29/2022]
Abstract
A significant amount of protein tyrosine phosphatase (PTP) activity was detected in the detergent-soluble membrane-bound fraction of Setaria cervi, a bovine filarial parasite. The membrane-bound PTP activity was significantly inhibited when the adult parasites were exposed to compounds having antifilarial activity like aspirin and SK7 as well as phenylarsine oxide, a specific PTP inhibitor suggesting that this activity is stress regulated. Further, this enzyme was purified as a single protein of apparently 21 kDa using two different chromatographic techniques. The MALDI-MS/MS analysis of its peptides showed closest match with protein tyrosine phosphatase PRL (Aedes aegypti). This purified enzyme (named as PRL) showed maximum activity at pH 5.5/37 °C and hydrolysed para nitro phenyl phosphate (pNPP) at the highest rate followed by O-P-L-tyrosine and O-P-L-threonine. It showed significant inhibition by specific inhibitors of PTP such as sodium orthovanadate, phenylarsine oxide and ammonium molybdate and was activated by dithiothreitol (DTT). The active site modification studies suggested involvement of cysteine, arginine, histidine and aspartic acid in the catalytic activity of PRL. The activity of S. cervi PRL was also found to be resistant towards the external oxidative stress. Thus, S. cervi PRL could be taken as a potential target for the management of human lymphatic filariasis.
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Affiliation(s)
- Neetu Singh
- Department of Biochemistry, Faculty of Science, Banaras Hindu University, Varanasi, 221005, India
| | - Smita Yadav
- Department of Biochemistry, Faculty of Science, Banaras Hindu University, Varanasi, 221005, India
| | - Sushma Rathaur
- Department of Biochemistry, Faculty of Science, Banaras Hindu University, Varanasi, 221005, India.
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The Leishmania donovani histidine acid ecto-phosphatase LdMAcP: insight into its structure and function. Biochem J 2015; 467:473-86. [PMID: 25695743 PMCID: PMC4687092 DOI: 10.1042/bj20141371] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Acid ecto-phosphatase activity has been implicated in Leishmania donovani promastigote virulence. In the present study, we report data contributing to the molecular/structural and functional characterization of the L. donovani LdMAcP (L. donovani membrane acid phosphatase), member of the histidine acid phosphatase (HAcP) family. LdMAcP is membrane-anchored and shares high sequence identity with the major secreted L. donovani acid phosphatases (LdSAcPs). Sequence comparison of the LdMAcP orthologues in Leishmania sp. revealed strain polymorphism and species specificity for the L. donovani complex, responsible for visceral leishmaniasis (Khala azar), proposing thus a potential value of LdMAcP as an epidemiological or diagnostic tool. The extracellular orientation of the LdMAcP catalytic domain was confirmed in L. donovani promastigotes, wild-type (wt) and transgenic overexpressing a recombinant LdMAcP–mRFP1 (monomeric RFP1) chimera, as well as in transiently transfected mammalian cells expressing rLdMAcP–His. For the first time it is demonstrated in the present study that LdMAcP confers tartrate resistant acid ecto-phosphatase activity in live L. donovani promastigotes. The latter confirmed the long sought molecular identity of at least one enzyme contributing to this activity. Interestingly, the L. donovani rLdMAcP–mRFP1 promastigotes generated in this study, showed significantly higher infectivity and virulence indexes than control parasites in the infection of J774 mouse macrophages highlighting thereby a role for LdMAcP in the parasite's virulence. Acid ecto-phosphatase activity has been linked to Leishmania donovani virulence. In the present study, we confirm the molecular identity and characterize molecular and functional properties of an enzyme contributing to this activity, the LdMAcP, an L. donovani specific membrane histidine acid phosphatase (HAcP).
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Biochemical properties and possible roles of ectophosphatase activities in fungi. Int J Mol Sci 2014; 15:2289-304. [PMID: 24509700 PMCID: PMC3958851 DOI: 10.3390/ijms15022289] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 11/27/2013] [Accepted: 01/14/2014] [Indexed: 12/31/2022] Open
Abstract
Ectophosphatases are surface membrane-bound proteins whose active sites face the extracellular medium. These enzymes have been reported in several microorganisms including a large number of medically relevant fungal species. An effective technique for identifying ectophosphatases is performing phosphatase activity assays using living intact cells. Biochemical characterization of these activities has shown their differential modulation by classical phosphatase inhibitors, divalent metals and pH range. The physiological roles of ectophosphatases are not well established; however, it has been suggested that these enzymes play important roles in nutrition, proliferation, differentiation, adhesion, virulence and infection. Adhesion to host cells is the first step in establishing a fungal infection and ectophosphatases may be one of the first parasite proteins that come into contact with the host cells. Several results indicate that ectophosphatase activities increase the capacity of fungi to adhere to the host cells. In this context, the present review provides an overview of recent discoveries related to the occurrence and possible roles of ectophosphatase activities in fungal cells.
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Freitas-Mesquita AL, Meyer-Fernandes JR. Ecto-nucleotidases and Ecto-phosphatases from Leishmania and Trypanosoma parasites. Subcell Biochem 2014; 74:217-252. [PMID: 24264248 DOI: 10.1007/978-94-007-7305-9_10] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Ecto-enzymes can be defined as membrane-bound proteins that have their active site facing the extracellular millieu. In trypanosomatids, the physiological roles of these enzymes remain to be completed elucidated; however, many important events have already been related to them, such as the survival of parasites during their complex life cycle and the successful establishment of host infection. This chapter focuses on two remarkable classes of ecto-enzymes: ecto-nucleotidases and ecto-phosphatases, summarizing their occurrence and possible physiological roles in Leishmania and Trypanosoma genera. Ecto-nucleotidases are characterized by their ability to hydrolyze extracellular nucleotides, playing an important role in purinergic signaling. By the action of these ecto-enzymes, parasites are capable of modulating the host immune system, which leads to a successful parasite infection. Furthermore, ecto-nucleotidases are also involved in the purine salvage pathway, acting in the generation of nucleosides that are able to cross plasma membrane via specialized transporters. Another important ecto-enzyme present in a vast number of pathogenic organisms is the ecto-phosphatase. These enzymes are able to hydrolyze extracellular phosphorylated substrates, releasing free inorganic phosphate that can be internalized by the cell, crossing the plasma membrane through a Pi-transporter. Ecto-phosphatases are also involved in the invasion and survival of parasite in the host cells. Several alternative functions have been suggested for these enzymes in parasites, such as participation in their proliferation, differentiation, nutrition and protection. In this context, the present chapter provides an overview of recent discoveries related to the occurrence of ecto-nucleotidase and ecto-phosphatase activities in Leishmania and Trypanosoma parasites.
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Freitas-Mesquita AL, Fonseca-de-Souza AL, Meyer-Fernandes JR. Leishmania amazonensis: characterization of an ecto-pyrophosphatase activity. Exp Parasitol 2013; 137:8-13. [PMID: 24316462 DOI: 10.1016/j.exppara.2013.11.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Revised: 11/22/2013] [Accepted: 11/27/2013] [Indexed: 01/30/2023]
Abstract
Several ecto-enzymatic activities have been described in the plasma membrane of the protozoan Leishmania amazonensis, which is the major etiological agent of diffuse cutaneous leishmaniasis in South America. These enzymes, including ecto-phosphatases, contribute to the survival of the parasite by participating in phosphate metabolism. This work identifies and characterizes the extracellular hydrolysis of inorganic pyrophosphate related to an ecto-pyrophosphatase activity of the promastigote form of L. amazonensis. This ecto-pyrophosphatase activity is insensitive to MnCl2 but is strongly stimulated by MgCl2. This stimulation was not observed during the hydrolysis of p-nitrophenyl phosphate (p-NPP) or β-glycerophosphate, two substrates for different ecto-phosphatases present in the L. amazonensis plasma membrane. Furthermore, extracellular PPi hydrolysis is more efficient at alkaline pHs, while p-NPP hydrolysis occurs mainly at acidic pHs. These results led us to conclude that extracellular PPi is hydrolyzed not by non-specific ecto-phosphatases but rather by a genuine ecto-pyrophosphatase. In the presence of 5mM MgCl2, the ecto-pyrophosphatase activity from L. amazonensis is sensitive to micromolar concentrations of NaF and millimolar concentrations of CaCl2. Moreover, this activity is significantly higher during the first days of L. amazonensis culture, which suggests a possible role for this enzyme in parasite growth.
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Affiliation(s)
- Anita Leocadio Freitas-Mesquita
- Instituto de Bioquímica Médica, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, 21941-590 Rio de Janeiro, RJ, Brazil; Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem, 21941-590 Rio de Janeiro, RJ, Brazil
| | - André Luiz Fonseca-de-Souza
- Laboratório de Terapia e Fisiologia Celular e Molecular, Centro Universitário Estadual da Zona Oeste, 23070-200 Rio de Janeiro, RJ, Brazil
| | - José Roberto Meyer-Fernandes
- Instituto de Bioquímica Médica, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, 21941-590 Rio de Janeiro, RJ, Brazil; Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem, 21941-590 Rio de Janeiro, RJ, Brazil.
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Trypanosoma rangeli: An alkaline ecto-phosphatase activity is involved with survival and growth of the parasite. Exp Parasitol 2013; 135:459-65. [DOI: 10.1016/j.exppara.2013.08.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Revised: 07/18/2013] [Accepted: 08/21/2013] [Indexed: 12/25/2022]
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16
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Catta-Preta CMC, Nascimento MTC, Garcia MCF, Saraiva EM, Motta MCM, Meyer-Fernandes JR. The presence of a symbiotic bacterium in Strigomonas culicis is related to differential ecto-phosphatase activity and influences the mosquito-protozoa interaction. Int J Parasitol 2013; 43:571-7. [PMID: 23562935 DOI: 10.1016/j.ijpara.2013.02.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Revised: 02/18/2013] [Accepted: 02/19/2013] [Indexed: 12/22/2022]
Abstract
Strigomonas culicis is a monoxenous trypanosomatid that co-evolves with a symbiotic bacterium in a mutualistic relationship that is characterized by intense metabolic exchanges between both partners. S. culicis infects and colonizes the Aedes aegypti mosquito midgut, reaches its hemocoel and then invades the salivary glands. An artificial aposymbiotic strain is unable to colonize insects, reinforcing the idea that the bacterium influences the protozoan surface composition and cell interaction. Here, we report the characterization of the hydrolytic activity of ecto-phosphatases evaluated in symbiont-bearing and aposymbiotic strains of S. culicis by incubating the protozoa with p-nitrophenyl phosphate (pNPP) at different pH levels, in the presence of phosphatase inhibitors, and with several divalent metals. The symbiont-bearing and aposymbiotic cells differ in their ecto-phosphatase enzymes, based on their activities and specificities. Furthermore, the ability of the protozoan to bind to the mosquito midgut and salivary glands was impaired by ecto-phosphatase inhibition. Taken together, our data suggest that the symbiont influences the host protozoan ecto-phosphatase activity and indicate a possible role of this enzyme during mosquito tissue colonization by S. culicis.
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Affiliation(s)
- C M C Catta-Preta
- Instituto de Biofísica Carlos Chagas Filho, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, UFRJ, Cidade Universitária, Ilha do Fundão, 21941-590 Rio de Janeiro, RJ, Brazil
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Fernandes AC, Soares DC, Saraiva EM, Meyer-Fernandes JR, Souto-Padrón T. Different secreted phosphatase activities inLeishmania amazonensis. FEMS Microbiol Lett 2013; 340:117-28. [DOI: 10.1111/1574-6968.12080] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Revised: 01/03/2013] [Accepted: 01/07/2013] [Indexed: 12/21/2022] Open
Affiliation(s)
- Anne C.S. Fernandes
- Instituto de Microbiologia Paulo de Góes; Centro de Ciências da Saúde; Universidade Federal do Rio de Janeiro; Rio de Janeiro; Brasil
| | - Deivid C. Soares
- Instituto de Microbiologia Paulo de Góes; Centro de Ciências da Saúde; Universidade Federal do Rio de Janeiro; Rio de Janeiro; Brasil
| | - Elvira M. Saraiva
- Instituto de Microbiologia Paulo de Góes; Centro de Ciências da Saúde; Universidade Federal do Rio de Janeiro; Rio de Janeiro; Brasil
| | - José R. Meyer-Fernandes
- Instituto de Bioquímica Médica; Centro de Ciências da Saúde; Universidade Federal do Rio de Janeiro; Rio de Janeiro; Brasil
| | - Thaïs Souto-Padrón
- Instituto de Microbiologia Paulo de Góes; Centro de Ciências da Saúde; Universidade Federal do Rio de Janeiro; Rio de Janeiro; Brasil
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Cosentino-Gomes D, Rocco-Machado N, Santi L, Broetto L, Vainstein MH, Meyer-Fernandes JR, Schrank A, Beys-da-Silva WO. Inhibition of ecto-phosphatase activity in conidia reduces adhesion and virulence of Metarhizium anisopliae on the host insect Dysdercus peruvianus. Curr Microbiol 2013; 66:467-74. [PMID: 23306352 DOI: 10.1007/s00284-012-0296-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Accepted: 12/03/2012] [Indexed: 01/17/2023]
Abstract
Metarhizium anisopliae is an entomopathogenic fungus with the ability to infect a broad range of arthropods, and have evolved distinct strategies for their attachment to hosts. Here, we describe the characterisation of ecto-phosphatase activity on the conidia surface of M. anisopliae and its relevance in the host interaction process. Ecto-phosphatase activity was linear for 60 min and during this time, was linear with the increase of cell density. The optimum pH was in the acidic range and some divalent metals, such as Cu(2+), Cd(2+) and Zn(2+), inhibited ecto-phosphatase activity. The activity was also reduced by phosphatase inhibitors. Importantly, the inhibition of phosphatase activity in conidia reduced the adhesion to Dysdercus peruvianus (Hemiptera: Pyrrhocoridae) integument and, consequently and indirectly, M. anisopliae infection. The results herein presented show, for the first time, the importance of ecto-phosphatase activity in M. anisopliae conidia and provide the first evidence of its direct involvement in adhesion and host infection.
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Affiliation(s)
- Daniela Cosentino-Gomes
- Instituto de Bioquímica Médica, Universidade Federal do Rio de Janeiro, CCS, Bloco H, Cidade Universitária, Ilha do Fundão, Rio de Janeiro, RJ 21941-902, Brazil
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Paletta-Silva R, Vieira-Bernardo R, Cosentino-Gomes D, Meyer-Fernandes JR. Leishmania amazonensis: Inhibition of 3′-nucleotidase activity by Cu2+ ions. Exp Parasitol 2012; 131:63-8. [DOI: 10.1016/j.exppara.2012.03.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Revised: 02/28/2012] [Accepted: 03/01/2012] [Indexed: 11/17/2022]
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Leishmania amazonensis: characterization of an ecto-3'-nucleotidase activity and its possible role in virulence. Exp Parasitol 2011; 129:277-83. [PMID: 21827749 DOI: 10.1016/j.exppara.2011.07.014] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Revised: 07/07/2011] [Accepted: 07/14/2011] [Indexed: 11/22/2022]
Abstract
Ecto-3'-nucleotidase/nuclease (3'NT/NU) is a membrane-bound enzyme that plays a key role in the nutrition of Leishmania sp. protozoan parasites. This enzyme generates nucleosides via hydrolyzes of 3'mononucleotides and nucleic acids, which enter the cell by specific transporters. In this work, we identify and characterize Leishmania amazonensis ecto-3'-nucleotidase activity (La3'-nucleotidase), report ammonium tetrathiomolybdate (TTM) as a novel La3'-nucleotidase inhibitor and approach the possible involvement of ecto-3'-nucleotidase in cellular adhesion. La3'-nucleotidase presented characteristics similar to those reported for the class I single-strand nuclease family; a molecular weight of approximately 40 kDa and optimum activity in an alkaline pH range were observed. Although it is conserved among the genus, La3'-nucleotidase displays different kinetic properties; it can be inhibited by vanadate, molybdate and Cu(2+) ions. Interestingly, ecto-3'-nucleotidase activity is 60-fold higher than that of ecto-5'-nucleotidase in L. amazonensis. Additionally, ecto-3'-nucleotidase activity is two-fold higher in virulent L. amazonensis cells than in avirulent ones. Notably, macrophage-parasite attachment/invasion was increased by 400% in the presence of adenosine 3'-monophosphate (3'AMP); however, this effect was reverted by TTM treatment. We believe that La3'-nucleotidase may play a significant role in the generation of adenosine, which may contribute to mammalian host immune response impairment and establishment of infection.
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Cosentino-Gomes D, Meyer-Fernandes JR. Ecto-phosphatases in protozoan parasites: possible roles in nutrition, growth and ROS sensing. J Bioenerg Biomembr 2011; 43:89-92. [PMID: 21253843 DOI: 10.1007/s10863-011-9334-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The cellular plasma membrane contains enzymes whose active sites face the external medium rather than the cytoplasm. The activities of these enzymes, referred to as ecto-enzymes, can be measured using living cells. Ecto-phosphatases are ecto-enzymes that presumably hydrolyze extracellular phosphorylated substrates, releasing free inorganic phosphate. Although, several alternative functions have been suggested for these enzymes, such as participation in proliferation, differentiation, adhesion, virulence, and infection, little is known about the physiological roles of these enzymes in protozoa parasites. In this review, we discuss the principal features of ecto-phosphatases in protozoan parasites that are causative agents of important diseases such as Chagas' disease, leishmaniasis, amoebiasis, giardiasis, trichomoniasis and, sleeping sickness.
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Affiliation(s)
- Daniela Cosentino-Gomes
- Instituto de Bioquímica Médica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
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22
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Possible roles of ectophosphatases in host-parasite interactions. J Parasitol Res 2011; 2011:479146. [PMID: 21603194 PMCID: PMC3095255 DOI: 10.1155/2011/479146] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2010] [Revised: 02/07/2011] [Accepted: 03/01/2011] [Indexed: 11/17/2022] Open
Abstract
The interaction and survival of pathogens in hostile environments and in confrontation with host immune responses are important mechanisms for the establishment of infection. Ectophosphatases are enzymes localized at the plasma membrane of cells, and their active sites face the external medium rather than the cytoplasm. Once activated, these enzymes are able to hydrolyze phosphorylated substrates in the extracellular milieu. Several studies demonstrated the presence of surface-located ecto-phosphatases in a vast number of pathogenic organisms, including bacteria, protozoa, and fungi. Little is known about the role of ecto-phosphatases in host-pathogen interactions. The present paper provides an overview of recent findings related to the virulence induced by these surface molecules in protozoa and fungi.
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Characterization of an ecto-5'-nucleotidase activity present on the cell surface of Tritrichomonas foetus. Vet Parasitol 2011; 179:50-6. [PMID: 21367528 DOI: 10.1016/j.vetpar.2011.01.061] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2010] [Revised: 01/24/2011] [Accepted: 01/30/2011] [Indexed: 12/20/2022]
Abstract
Tritrichomonas foetus is the causative agent of sexually transmitted trichomoniasis in cattle. In females, the infection can be associated with infertility, vaginitis, endometritis, abortion or pyometra, leading to significant economic losses in cattle raising. T. foetus is devoid of the ability to synthesize purine nucleotides de novo, depending instead on salvaging purines from the host environment. Ecto-5'-nucleotidase catalyzes the final step of extracellular nucleotide degradation, the hydrolysis of nucleoside 5'-monophosphates to the corresponding nucleosides and Pi. In this work we show that living, intact cells of T. foetus were able to hydrolyze 5'AMP at a rate of 12.57 ± 1.23 nmol Pi × h(-1) × 10(-7) cells at pH 7.2 and the 5'AMP hydrolysis is due to a plasma membrane-bound ecto-enzyme activity. The apparent K(m) for 5'AMP was 0.49 ± 0.06 mM. In addition to 5'AMP, the enzyme hydrolyzed all substrate monophosphates tested except 3'AMP. No divalent metals or metal chelators were able to modulate enzyme activity. Phosphatase inhibitors did not have an effect on ecto-5'-nucleotidase activity while ammonium molybdate did inhibit the activity in a dose dependent manner. The presence of adenosine in the culture medium negatively modulated the enzyme. These results indicate the existence of an ecto-5'-nucleotidase that may play a role in the salvage of purines.
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Russo-Abrahão T, Cosentino-Gomes D, Daflon-Yunes N, Meyer-Fernandes JR. Giardia duodenalis: biochemical characterization of an ecto-5'-nucleotidase activity. Exp Parasitol 2010; 127:66-71. [PMID: 20599434 DOI: 10.1016/j.exppara.2010.06.028] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2010] [Revised: 06/24/2010] [Accepted: 06/28/2010] [Indexed: 12/01/2022]
Abstract
In this work, we biochemically characterized the ecto-5'-nucleotidase activity present on the surface of the living trophozoites of Giardia duodenalis. Two sequences of the 5'-nucleotidase family protein were identified in the Giardia genome. Anti-mouse CD73 showed a high reaction with the cell surface of parasites. At pH 7.2, intact cells were able to hydrolyze 5'-AMP at a rate of 10.66 ± 0.92 nmol Pi/h/10(7) cells. AMP is the best substrate for this enzyme, and the optimum pH lies in the acidic range. No divalent cations had an effect on the ecto-5'-nucleotidase activity, and the same was seen for NaF, an acid phosphatase inhibitor. Ammonium molybdate, a potent inhibitor of nucleotidases, inhibited the enzyme activity in a dose-dependent manner. The presence of adenosine in the culture medium negatively modulated the enzyme. The results indicate the existence of an ecto-5'-nucleotidase that could play a role in the salvage of purines.
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Affiliation(s)
- Thais Russo-Abrahão
- Instituto de Bioquímica Médica, Universidade Federal do Rio de Janeiro, CCS, Bloco H, Cidade Universitária, Ilha do Fundão, 21941-590 Rio de Janeiro, RJ, Brazil
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Trypanosoma rangeli: Differential expression of ecto-phosphatase activities in response to inorganic phosphate starvation. Exp Parasitol 2010; 124:386-93. [DOI: 10.1016/j.exppara.2009.12.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2009] [Revised: 11/16/2009] [Accepted: 12/12/2009] [Indexed: 01/25/2023]
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Trypanosoma rangeli: A possible role for ecto-phosphatase activity on cell proliferation. Exp Parasitol 2009; 122:242-6. [DOI: 10.1016/j.exppara.2009.03.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2008] [Revised: 01/06/2009] [Accepted: 03/06/2009] [Indexed: 12/16/2022]
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Setaria cervi dual specific phosphatase: characterization and its effect on eosinophil degranulation. Parasitology 2009; 136:895-904. [PMID: 19523248 DOI: 10.1017/s0031182009006271] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Setaria cervi, a bovine filarial parasite contains significant acid phosphatase (AcP) activity in its various life stages. Two forms of AcP were separated from somatic extract of adult female parasite using cation exchange, gel filtration and concavalin affinity chromatography. One form having a molecular mass of 79 kDa was characterized as dual specific protein tyrosine phosphatase (ScDSP) based on substrate specificity and inhibition studies. With various substrates tested, it showed significant activity in the order of phospho-L-tyrosine>pNPP>ADP>phospho-L-serine. Inhibition by orthovanadate, fluoride, molybdate, and zinc ions further confirms protein tyrosine phosphatase nature of the enzyme. Km and Vmax determined with various substrates were found to be 16.66 mM, 25.0 microM/ml/min with pNPP; 20.0 mM, 40.0 microM/ml/min with phospho-L-tyrosine and 27.0 mM, 25.0 microM/ml/min with phospho-L-serine. KI with pNPP and sodium orthovanadate (IC50 33.0 microM) was calculated to be 50.0 mM. Inhibition with pHMB, silver nitrate, DEPC and EDAC suggested the presence of cysteine, histidine and carboxylate residues at its active site. Cross-reactivity with W. bancrofti-infected sera was demonstrated by Western blotting. ScDSP showed elevated levels of IgE in chronic filarial sera using ELISA. Under in vitro conditions, ScDSP resulted in increased effector function of human eosinophils when stimulated by IgG, which showed a further decrease with increasing enzyme concentration. Results presented here suggest that S. cervi DSP should be further studied to determine its role in pathogenesis and the persistence of filarial parasite.
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Poorrajab F, Ardestani SK, Foroumadi A, Emami S, Kariminia A, Behrouzi-Fardmoghadam M, Shafiee A. Selective leishmanicidal effect of 1,3,4-thiadiazole derivatives and possible mechanism of action against Leishmania species. Exp Parasitol 2009; 121:323-30. [DOI: 10.1016/j.exppara.2008.12.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2008] [Revised: 12/03/2008] [Accepted: 12/05/2008] [Indexed: 11/29/2022]
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Amazonas JN, Cosentino-Gomes D, Werneck-Lacerda A, de Sá Pinheiro AA, Lanfredi-Rangel A, Souza WD, Meyer-Fernandes JR. Giardia lamblia: Characterization of ecto-phosphatase activities. Exp Parasitol 2009; 121:15-21. [DOI: 10.1016/j.exppara.2008.09.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2008] [Revised: 09/16/2008] [Accepted: 09/18/2008] [Indexed: 11/29/2022]
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30
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Leite MS, Thomaz R, Oliveira JHM, Oliveira PL, Meyer-Fernandes JR. Trypanosoma brucei brucei: effects of ferrous iron and heme on ecto-nucleoside triphosphate diphosphohydrolase activity. Exp Parasitol 2008; 121:137-43. [PMID: 19027737 DOI: 10.1016/j.exppara.2008.10.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2008] [Revised: 10/09/2008] [Accepted: 10/24/2008] [Indexed: 01/17/2023]
Abstract
Trypanosoma brucei brucei is the causative agent of animal African trypanosomiasis, also called nagana. Procyclic vector form resides in the midgut of the tsetse fly, which feeds exclusively on blood. Hemoglobin digestion occurs in the midgut resulting in an intense release of free heme. In the present study we show that the magnesium-dependent ecto-nucleoside triphosphate diphosphohydrolase (E-NTPDase) activity of procyclic T. brucei brucei is inhibited by ferrous iron and heme. The inhibition of E-NTPDase activity by ferrous iron, but not by heme, was prevented by pre-incubation of cells with catalase. However, antioxidants that permeate cells, such as PEG-catalase and N-acetyl-cysteine prevented the inhibition of E-NTPDase by heme. Ferrous iron was able to induce an increase in lipid peroxidation, while heme did not. Therefore, both ferrous iron and heme can inhibit E-NTPDase activity of T. brucei brucei by means of formation of reactive oxygen species, but apparently acting through distinct mechanisms.
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Affiliation(s)
- Milane S Leite
- Laboratório de Bioquímica Celular, Instituto de Bioquímica Médica, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, UFRJ, Cidade Universitária, Ilha do Fundão, Rio de Janeiro, Brazil
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Fonseca-de-Souza AL, Dick CF, Dos Santos ALA, Meyer-Fernandes JR. A Mg(2+)-dependent ecto-phosphatase activity on the external surface of Trypanosoma rangeli modulated by exogenous inorganic phosphate. Acta Trop 2008; 107:153-8. [PMID: 18599005 DOI: 10.1016/j.actatropica.2008.05.017] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2008] [Revised: 05/16/2008] [Accepted: 05/22/2008] [Indexed: 11/30/2022]
Abstract
In this work, we characterized a Mg(2+)-dependent ecto-phosphatase activity present in live Trypanosoma rangeli epimastigotes. This enzyme showed capacity to hydrolyze the artificial substrate for phosphatases, p-nitrophenylphosphate (p-NPP). At saturating concentration of p-NPP, half-maximal p-NPP hydrolysis was obtained with 0.23mM Mg(2+). Ca(2+) had no effect on the basal phosphatase activity, could not substitute Mg(2+) as an activator and in contrast inhibited the p-NPP hydrolysis stimulated by Mg(2+). The dependence on p-NPP concentration showed a normal Michaelis-Menten kinetics for this phosphatase activity with values of V(max) of 8.94+/-0.36 nmol p-NP x h(-1) x 10(-7) cells and apparent K(m) of 1.04+/-0.16 mM p-NPP. Mg(2+)-dependent ecto-phosphatase activity was stimulated by the alkaline pH range. Experiments using inhibitors, such as, sodium fluoride, sodium orthovanadate and ammonium molybdate, inhibited the Mg(2+)-dependent ecto-phosphatase activity. Inorganic phosphate (Pi), a product of phosphatases, inhibited reversibly in 50% this activity. Okadaic acid and microcystin-LR, specific phosphoserine/threonine phosphatase inhibitors, inhibited significantly the Mg(2+)-dependent ecto-phosphatase activity. In addition, this phosphatase activity was able to recognize as substrates only o-phosphoserine and o-phosphothreonine, while o-phosphotyrosine was not a good substrate for this phosphatase. Epimastigote forms of T. rangeli exhibit a typical growth curve, achieving the stationary phase around fifth or sixth day and the Mg(2+)-dependent ecto-phosphatase activity decreased around 10-fold with the cell growth progression. Cells maintained at Pi-deprived medium (2 mM Pi) present Mg(2+)-dependent ecto-phosphatase activity approximately threefold higher than that maintained at Pi-supplemented medium (50 mM Pi).
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Affiliation(s)
- André L Fonseca-de-Souza
- Laboratório de Bioquímica Celular, Instituto de Bioquímica Medica, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, UFRJ, Cidade Universitária, Ilha do Fundão, Rio de Janeiro, RJ, Brazil
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Ecto-phosphatase activity on the external surface of Rhodnius prolixus salivary glands: modulation by carbohydrates and Trypanosoma rangeli. Acta Trop 2008; 106:137-42. [PMID: 18407240 DOI: 10.1016/j.actatropica.2008.02.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2007] [Revised: 02/26/2008] [Accepted: 02/28/2008] [Indexed: 12/24/2022]
Abstract
The salivary glands of insect's vectors are target organs to study the vectors-pathogens interactions. Rhodnius prolixus an important vector of Trypanosoma cruzi can also transmit Trypanosoma rangeli by bite. In the present study we have investigated ecto-phosphatase activity on the surface of R. prolixus salivary glands. Ecto-phosphatases are able to hydrolyze phosphorylated substrates in the extracellular medium. We characterized these ecto-enzyme activities on the salivary glands external surface and employed it to investigate R. prolixus-T. rangeli interaction. Salivary glands present a low level of hydrolytic activity (4.30+/-0.35 nmol p-nitrophenol (p-NP)xh(-1)xgland pair(-1)). The salivary glands ecto-phosphatase activity was not affected by pH variation; and it was insensitive to alkaline inhibitor levamisole and inhibited approximately 50% by inorganic phosphate (Pi). MgCl2, CaCl2 and SrCl2 enhanced significantly the ecto-phosphatase activity detected on the surface of salivary glands. The ecto-phosphatase from salivary glands surface efficiently releases phosphate groups from different phosphorylated amino acids, giving a higher rate of phosphate release when phospho-tyrosine is used as a substrate. This ecto-phosphatase activity was inhibited by carbohydrates as d-galactose and d-mannose. Living short epimastigotes of T. rangeli inhibited salivary glands ecto-phosphatase activity at 75%, while boiled parasites did not. Living long epimastigote forms induced a lower, but significant inhibitory effect on the salivary glands phosphatase activity. Interestingly, boiled long epimastigote forms did not loose the ability to modulate salivary glands phosphatase activity. Taken together, these data suggest a possible role for ecto-phosphatase on the R. prolixus salivary glands-T. rangeli interaction.
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Hopfe M, Henrich B. OppA, the ecto-ATPase of Mycoplasma hominis induces ATP release and cell death in HeLa cells. BMC Microbiol 2008; 8:55. [PMID: 18394151 PMCID: PMC2323007 DOI: 10.1186/1471-2180-8-55] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2007] [Accepted: 04/04/2008] [Indexed: 12/21/2022] Open
Abstract
Background In the facultative human pathogen Mycoplasma hominis, which belongs to the cell wall-less Mollicutes, the surface-localised substrate-binding domain OppA of the oligopeptide permease was characterised as the main ecto-ATPase. Results With the idea that extra-cellular ATP could only be provided by the infected host cells we analysed the ATP release of HeLa cells after incubation with different preparations of Mycoplasma hominis: intact bacterial cells, the membrane fraction with or without OppA, recombinant OppA as well as an ATPase-deficient OppA mutant. Release of ATP into the supernatant of the HeLa cells was primarily determined in all samples lacking ecto-ATPase activity of OppA. In the presence of the ATPase inhibitor DIDS the amount of ATP in the OppA-containing samples increased. This increase was maximal after incubation with fractions containing OppA protein indicating that OppA is involved in ATP release and subsequent hydrolysis. Real-time PCR analyses revealed that the proliferation of HeLa cells is reduced after infection with M. hominis and flow cytometry experiments established that OppA induces greater apoptosis than necrosis of HeLa cells whereas the preservation of ecto-ATPase activity of OppA induces apoptosis. Conclusion The OppA induced ATP-release and -hydrolysis induced cell death of M. hominis infected HeLa cells was predominantly due to apoptosis rather than necrosis. Future work will elucidate whether the induction of apoptosis is indispensable for survival of these non-invasive pathogen.
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Affiliation(s)
- Miriam Hopfe
- Institute of Medical Microbiology and Center for Biological Medical Research, Heinrich-Heine-University, Moorenstrasse 5, 40225 Duesseldorf, Germany.
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de Sá Pinheiro AA, Cosentino-Gomes D, Lanfredi-Rangel A, Ferraro RB, De Souza W, Meyer-Fernandes JR. Giardia lamblia: biochemical characterization of an ecto-ATPase activity. Exp Parasitol 2008; 119:279-84. [PMID: 18413274 DOI: 10.1016/j.exppara.2008.02.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2007] [Revised: 02/19/2008] [Accepted: 02/27/2008] [Indexed: 10/22/2022]
Abstract
In this work, we describe the ability of living trophozoites of Giardia lamblia to hydrolyze extracellular ATP. In the absence of any divalent cations, a low level of ATP hydrolysis was observed (0.78+/-0.08 nmol Pi x h(-1)x10(-6) cells). The ATP hydrolysis was stimulated by MgCl(2) in a dose-dependent manner. Half maximum stimulation of ATP hydrolysis was obtained with 0.53+/-0.07 mM. ATP was the best substrate for this enzyme. The apparent K(m) for ATP was 0.21+/-0.04 mM. In the pH range from 5.6 to 8.4, in which cells were viable, this activity was not modified. The Mg(2+)-stimulated ATPase activity was insensitive to inhibitors of intracellular ATPases such as vanadate (P-ATPases), bafilomycin A(1) (V-ATPases), and oligomycin (F-ATPases). Inhibitors of acid phosphatases (molybdate, vanadate and fluoride) or alkaline phosphatases (levamizole) had no effect on the ecto-ATPase activity. The impermeant agent DIDS and suramin, an antagonist of P2 purinoreceptors and inhibitor of some ecto-ATPases, decreased the enzymatic activity in a dose-dependent manner, confirming the external localization of this enzyme. Besides ATP, trophozoites were also able to hydrolyse ADP and 5 AMP, but the hydrolysis of these nucleotides was not stimulated by MgCl(2). Our results are indicative of the occurrence of a G. lamblia ecto-ATPase activity that may have a role in parasite physiology.
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Affiliation(s)
- Ana Acacia de Sá Pinheiro
- Instituto de Bioquímica Médica, Universidade Federal do Rio de Janeiro, Cidade Universitária, Ilha do Fundão, 21941-590, Rio de Janeiro, RJ, Brazil
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Peres-Sampaio CE, de Almeida-Amaral EE, Giarola NLL, Meyer-Fernandes JR. Leishmania amazonensis: effects of heat shock on ecto-ATPase activity. Exp Parasitol 2008; 119:135-43. [PMID: 18295760 DOI: 10.1016/j.exppara.2008.01.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2007] [Revised: 11/30/2007] [Accepted: 01/11/2008] [Indexed: 10/22/2022]
Abstract
In this work we demonstrated that promastigotes of Leishmania amazonensis exhibit an Mg-dependent ecto-ATPase activity, which is stimulated by heat shock. The Mg-dependent ATPase activity of cells grown at 22 and 28 degrees C was 41.0+/-5.2 nmol Pi/h x 10(7)cells and 184.2+/-21.0 nmol Pi/h x 10(7)cells, respectively. When both promastigotes were pre-incubated at 37 degrees C for 2h, the ATPase activity of cells grown at 22 degrees C was increased to 136.4+/-10.6 nmol Pi/h x 10(7) whereas that the ATPase activity of cells grown at 28 degrees C was not modified by the heat shock (189.8+/-10.3 nmol Pi/h x 10(7)cells). It was observed that Km of the enzyme from cells grown at 22 degrees C (Km=980.2+/-88.6 microM) was the same to the enzyme from cells grown at 28 degrees C (Km=901.4+/-91.9 microM). In addition, DIDS (4,4'-diisothiocyanatostilbene 2,2'-disulfonic acid) and suramin, two inhibitors of ecto-ATPases, also inhibited similarly the ATPase activities from promastigotes grown at 22 and 28 degrees C. We also observed that cells grown at 22 degrees C exhibit the same ecto-phosphatase and ecto 3'- and 5'-nucleotidase activities than cells grown at 28 degrees C. Interestingly, cycloheximide, an inhibitor of protein synthesis, suppressed the heat-shock effect on ecto-ATPase activity of cells grown at 22 degrees C were exposed at 37 degrees C for 2h. A comparison between the stimulation of the Mg-dependent ecto-ATPase activity of virulent and avirulent promastigotes by the heat shock showed that avirulent promastigotes had a higher stimulation than virulent promastigotes after heat stress.
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Affiliation(s)
- Carlos Eduardo Peres-Sampaio
- Faculdade de Enfermagem-FENF, Centro Biomédico, Universidade do Estado do Rio de Janeiro-UERJ, Av. 28 de setembro 87, Vila Isabel, 20551-030, Rio de Janeiro, RJ, Brazil
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Kiffer-Moreira T, Pinheiro AAS, Pinto MR, Esteves FF, Souto-Padrón T, Barreto-Bergter E, Meyer-Fernandes JR. Mycelial forms of Pseudallescheria boydii present ectophosphatase activities. Arch Microbiol 2007; 188:159-66. [PMID: 17429613 DOI: 10.1007/s00203-007-0232-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2007] [Revised: 02/28/2007] [Accepted: 03/05/2007] [Indexed: 10/23/2022]
Abstract
Phosphatase activities were characterized in intact mycelial forms of Pseudallescheria boydii, which are able to hydrolyze the artificial substrate p-nitrophenylphosphate (p-NPP) to p-nitrophenol (p-NP) at a rate of 41.41+/-2.33 nmol p-NP per h per mg dry weight, linearly with increasing time and with increasing cell density. MgCl2, MnCl2 and ZnCl2 were able to increase the (p-NPP) hydrolysis while CdCl2 and CuCl2 inhibited it. The (p-NPP) hydrolysis was enhanced by increasing pH values (2.5-8.5) over an approximately 5-fold range. High sensitivity to specific inhibitors of alkaline and acid phosphatases suggests the presence of both acid and alkaline phosphatase activities on P. boydii mycelia surface. Cytochemical localization of the acid and alkaline phosphatase showed electron-dense cerium phosphate deposits on the cell wall, as visualized by electron microscopy. The product of p-NPP hydrolysis, inorganic phosphate (Pi), and different inhibitors for phosphatase activities inhibited p-NPP hydrolysis in a dose-dependent manner, but only the inhibition promoted by sodium orthovanadate and ammonium molybdate is irreversible. Intact mycelial forms of P. boydii are also able to hydrolyze phosphoaminoacids with different specificity.
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Affiliation(s)
- Tina Kiffer-Moreira
- Instututo de Bioquímica Médica, Universidade Federal do Rio de Janeiro, CCS, bloco H, Cidade Universitária, Rio de Janeiro, RJ, 21941-590, Brazil
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