Entamoeba histolytica: Oxygen resistance and virulence

Ramos-Martı́nez, Espiridión; Olivos-García, Alfonso; Saavedra, Emma; Néquiz, Mario; Sánchez, Ernesto Carlos; Tello, Eusebio; El-Hafidi, Mohamed; Saralegui, Andrés; Pineda, Erika; Delgado, João; Montfort, Irmgard; Pérez-Tamayo, Ruy

doi:10.1016/j.ijpara.2008.11.004

Cited by 40 publications

(44 citation statements)

References 67 publications

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“…This parasite usually lives and multiplies in the low-oxygen environment of the human gut. When E. histolytica invades human tissues, it is challenged by a high-oxygen environment (~0.24 mM) (Ramos-Martínez et al, 2009) and by the ROS produced by endogenous enzymes and activated phagocytes during the respiratory burst (Santi-Rocca et al, 2009). Moreover, the steady-state intracellular concentration of H 2 O 2 is regulated at concentrations up to 10 29 -10 27 M. The physiological or pathological variation of catalase concentration in different organs and tissues will lead to different steady-state levels of H 2 O 2 concentration for the same rate of H 2 O 2 generation (Chance et al, 1979).…”

Section: Discussionmentioning

confidence: 99%

Hydrogen peroxide induces apoptosis-like death in Entamoeba histolytica trophozoites

et al. 2010

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Programmed cell death (PCD) is an essential process in the growth and development of multicellular organisms. However, accumulating evidence indicates that unicellular eukaryotes can also undergo PCD with apoptosis-like features. This study demonstrates that after exposure to 0.8 mM H 2 O 2 for 9 h Entamoeba histolytica presents morphological and biochemical evidence of apoptosis-like death. Morphological characteristics of apoptosis-like death including DNA fragmentation, increased vacuolization, nuclear condensation and cell rounding were observed for H 2 O 2 -exposed trophozoites with preservation of membrane integrity. Biochemical alteration in ion fluxes is also a key feature in PCD, and H 2 O 2 -exposed trophozoites showed overproduction of reactive oxygen species, increased cytosolic Ca 2+ and decreased intracellular pH.Phosphatidylserine was also found to be expressed in the outer leaflet of the plasma membrane of the H 2 O 2 -treated trophozoites. Pretreatment with the cysteine protease inhibitor E-64d, the extracellular and intracellular Ca 2+ chelators EGTA and BAPTA/AM, and the Ca 2+ influx inhibitor verapamil prior to H 2 O 2 exposure abolished DNA fragmentation. The oxidatively stressed trophozoites also showed an increased calpain activity, indicating involvement of Ca 2+ -dependent calpain-like cysteine proteases in PCD of E. histolytica. A homogeneous caspase assay showed no significant caspase activity, and administration of caspase 1 inhibitor also did not prevent the death phenotype for the oxidatively stressed trophozoites, indicating a caspaseindependent apoptosis-like death. Our observations clearly demonstrate that there is a distinct calpain-dependent but caspase-independent pathway for apoptosis-like death in oxidatively stressed E. histolytica trophozoites.

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Section: Discussionmentioning

confidence: 99%

Hydrogen peroxide induces apoptosis-like death in Entamoeba histolytica trophozoites

et al. 2010

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“…The susceptibility (14,15,26) and transcriptional response (1,42) of E. histolytica to oxygen and ROS have long been addressed. It has been observed that Entamoeba species and E. histolytica strains with higher virulence are more resistant to oxygen (28) and display higher expression of genes and proteins related to the oxidative stress response (1,9,24,42). Resistance to oxygen-derived stress is thus likely an important component of the E. histolytica virulence framework (28).…”

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confidence: 99%

“…It has been observed that Entamoeba species and E. histolytica strains with higher virulence are more resistant to oxygen (28) and display higher expression of genes and proteins related to the oxidative stress response (1,9,24,42). Resistance to oxygen-derived stress is thus likely an important component of the E. histolytica virulence framework (28). Oxygen reduction activity has been attributed to different E. histolytica flavoproteins (6,7,17), although most produce hydrogen peroxide and thus require further detoxification enzymes.…”

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confidence: 99%

A Detoxifying Oxygen Reductase in the Anaerobic Protozoan Entamoeba histolytica

et al. 2012

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ABSTRACTWe report the characterization of a bacterial-type oxygen reductase abundant in the cytoplasm of the anaerobic protozoan parasiteEntamoeba histolytica. Upon host infection,E. histolyticais confronted with various oxygen tensions in the host intestine, as well as increased reactive oxygen and nitrogen species at the site of local tissue inflammation. Resistance to oxygen-derived stress thus plays an important role in the pathogenic potential ofE. histolytica. The genome ofE. histolyticahas four genes that encode flavodiiron proteins, which are bacterial-type oxygen or nitric oxide reductases and were likely acquired by lateral gene transfer from prokaryotes. TheEhFdp1gene has higher expression in virulent than in nonvirulentEntamoebastrains and species, hinting that the response to oxidative stress may be one correlate of virulence potential. We demonstrate that EhFdp1 is abundantly expressed in the cytoplasm ofE. histolyticaand that the protein levels are markedly increased (up to ∼5-fold) upon oxygen exposure. Additionally, we produced fully functional recombinant EhFdp1 and demonstrated that this enzyme is a specific and robust oxygen reductase but has poor nitric oxide reductase activity. This observation represents a new mechanism of oxygen resistance in the anaerobic protozoan pathogenE. histolytica.

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“…Our data are consistent with the premise that L-cysteine depletion-mediated oxidative stress inactivates pyruvate:ferredoxin oxidoreductase and other redox-sensitive enzymes, which results in the overall reduction in the glycolytic flux and the accumulation of upstream glycolytic intermediates. It has been shown in E. histolytica that under oxidative or nitrosative stress, pyruvate, glucose 6-phosphate, and fructose 6-phosphate accumulate, whereas ethanol and ATP decrease (33,56). Unlike nitrosative stress, L-cysteine depletion for 48 h did not induce apoptosis (data not shown), and the decrease in ATP content appears to be primarily a result of the reduced glycolytic flux.…”

Section: Identification Of Smc and Oas As The Major Metabolitesmentioning

confidence: 83%

“…The produced hydrogen peroxide was then reacted with Amplex Red reagent in a 1:1 stoichiometry in the presence of horseradish peroxidase to generate the highly fluorescent product resorufin, which was read in a fluorescence spectrophotometer (model F-2500; Hitachi) at excitation and emission wavelengths of 545 and 590 nm, respectively. Ethanol production by trophozoites cultured in either normal or L-cysteine-deprived medium was determined as described previously (33).…”

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confidence: 99%

Metabolome Analysis Revealed Increase in S-Methylcysteine and Phosphatidylisopropanolamine Synthesis upon l-Cysteine Deprivation in the Anaerobic Protozoan Parasite Entamoeba histolytica

Husain

Sato

Jeelani

et al. 2010

Journal of Biological Chemistry

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L-Cysteine is ubiquitous in all living organisms and is involved in a variety of functions, including the synthesis of iron-sulfur clusters and glutathione and the regulation of the structure, stability, and catalysis of proteins. In the protozoan parasite Entamoeba histolytica, the causative agent of amebiasis, L-cysteine plays an essential role in proliferation, adherence, and defense against oxidative stress; however, the essentiality of this amino acid in the pathways it regulates is not well understood. In the present study, we applied capillary electrophoresis time-of-flight mass spectrometry to quantitate charged metabolites modulated in response to L-cysteine deprivation in E. histolytica, which was selected as a model for examining the biological roles of L-cysteine. L-Cysteine deprivation had profound effects on glycolysis, amino acid, and phospholipid metabolism, with sharp decreases in the levels of L-cysteine, L-cystine, and S-adenosylmethionine and a dramatic accumulation of O-acetylserine and S-methylcysteine. We further demonstrated that S-methylcysteine is synthesized from methanethiol and O-acetylserine by cysteine synthase, which was previously considered to be involved in sulfur-assimilatory L-cysteine biosynthesis. In addition, L-cysteine depletion repressed glycolysis and energy generation, as it reduced acetylCoA, ethanol, and the major nucleotide di-and triphosphates, and led to the accumulation of glycolytic intermediates. Interestingly, L-cysteine depletion increased the synthesis of isopropanolamine and phosphatidylisopropanolamine, and it was confirmed that their increment was not a result of oxidative stress but was a specific response to L-cysteine depletion. We also identified a pathway in which isopropanolamine is synthesized from methylglyoxal via aminoacetone. To date, this study represents the first case where L-cysteine deprivation leads to drastic changes in core metabolic pathways, including energy, amino acid, and phospholipid metabolism.Sulfur-containing amino acids are essential for all living organisms from bacteria to higher eukaryotes and play indispensable roles in various cellular processes, such as methylation and the generation of polyamines, iron-sulfur clusters, and antioxidants. L-Cysteine in particular is essential for the structure, stability, and various protein functions, including catalysis, electron transfer, redox regulation, nitrogen fixation, and sensing for regulatory processes (1).Entamoeba histolytica is an enteric protozoan parasite that causes hemorrhagic dysentery and extraintestinal abscesses in millions of inhabitants of endemic areas (2). This parasite is generally considered as anaerobic/microaerophilic and has been shown to consume oxygen and tolerate low levels of oxygen pressure but lacks most of the components of antioxidant defense mechanisms, such as catalase, peroxidase, glutathione, and the glutathione-recycling enzymes glutathione peroxidase and glutathione reductase (3, 4). L-Cysteine, which replaces glutathione as a major thiol in E...

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Entamoeba histolytica: Oxygen resistance and virulence

Cited by 40 publications

References 67 publications

Hydrogen peroxide induces apoptosis-like death in Entamoeba histolytica trophozoites

Hydrogen peroxide induces apoptosis-like death in Entamoeba histolytica trophozoites

A Detoxifying Oxygen Reductase in the Anaerobic Protozoan Entamoeba histolytica

Metabolome Analysis Revealed Increase in S-Methylcysteine and Phosphatidylisopropanolamine Synthesis upon l-Cysteine Deprivation in the Anaerobic Protozoan Parasite Entamoeba histolytica

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