Biochemical Cytology of Trichomonad Flagellates

Müller, Miklós

doi:10.1083/jcb.57.2.453

Cited by 103 publications

(19 citation statements)

References 24 publications

(30 reference statements)

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“…3), an observation which is consistent with a rather small size of the organelles [25], as observed in electron micrographs of fractions obtained by isopycnic centrifugation [9].…”

Section: Latency Of Glycosomal Enzymessupporting

confidence: 66%

Glycolysis in Trypanosoma brucei

Visser

Opperdoes

1980

European Journal of Biochemistry

122

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The possibility that the glycosomes present in the bloodstream form of Trypanosoma brucei FEBS Lett. 80, 360-3641 constitute a separate pool of glycolytic intermediates within the cell was investigated.In titrations of intact cells with digitonin, a differential activation of glycolytic enzymes was observed. Enolase, pyruvate kinase and the cell-sap marker alanine aminotransferase were activated at 0.05 mg digitonin per mg protein. The nine glycosomal enzymes involved in the conversion of glucose and glycerol into 3-phosphoglycerate were activated only at digitonin concentrations between 0.7 and 9.8 mg/mg protein. In subcellular fractions the activities or the latter enzymes were all latent between 70 and 92 %. Latency was abolished by addition of 0.1 % Triton X-100 or partly by five cycles of freezing and thawing. We conclude that the glycosomal enzymes are surrounded by a membrane, which forms a permeability barrier to intermediates and co-factors of glycolysis.The concentrations of glycolytic intermediates and of adenine nucleotides were measured under aerobic conditions as well as in the presence of 1 mM salicylhydroxamic acid, a respiratory inhibitor. Addition of salicylhydroxamic acid caused the following changes : (a) The levels of almost all glycolytic intermediates measured decreased. Glycerol-3-phosphate, however, increased fourfold. From the high levels of metabolite concentrations found and from comparison of the apparent mass-action ratios calculated for the separate glycolytic reactions with those for other organisms, we conclude that in bloodstream form T. brucei the glycolytic intermediates are present in the glycosomes as well as in the cytosol and that the two pools of intermediates equilibrate with each other, despite the presence of the glycosomal membrane.Bloodstream forms of the African trypanosomes belonging to the brucei group, like Trypanosoma brucei, Trypanosoma rhodesiense and Trypanosoma gambiense, are the causative agents of nagana in domestic animals Abbreviations. Dihydroxyacetone-P, dihydroxyacetone phosphate ; glycerol-3-P, sn-glycerol-3-phosphate; glycerate-3-P, 3-phosphoglycerate; glucose-6-P, glucose-6-phosphate; fructose-6-P, fructose-6-phosphate; fructose-l,h-Pz, fructose-1,6-bisphosphate; glycerate-2-P, 2-phosphoglycerate; glyceraldehyde-3-P, D-glyceraldehyde-3-phosphate.Enzymes. Hexokinase (EC 2.7.1.1); phosphoglucose isomerase (EC 5.3.1.9); 6-phosphofructokinase (EC 2.7.1.11); fructose-bisphosphate aldolase (EC 4.1.2.13); triosephosphate isomerase (EC 5.3.1 .l): sn-glycerol-3-phosphate dehydrogenase (EC 1.1.1.8); glycerol kinase (EC 2.7.1.30); glyceraldehyde-phosphate dehydrogenase (EC 1.2.1.12); phosphoglycerate kinase (EC 2.7.2.3); phosphoglyceromutase (EC 2.7.5.3); enolase (EC 4.2.1.11); pyruvate kinase (EC 2.7.1.40); alanine aminotransferase (EC 2.6.1.2). and live-stock and of the acute and chronic forms of sleeping sickness in man. For their energy needs, these organisms are entirely dependent on glycolysis which proceeds at an extremely high rate and differs in its...

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“…3), an observation which is consistent with a rather small size of the organelles [25], as observed in electron micrographs of fractions obtained by isopycnic centrifugation [9].…”

Section: Latency Of Glycosomal Enzymessupporting

confidence: 66%

Glycolysis in Trypanosoma brucei

Visser

Opperdoes

1980

European Journal of Biochemistry

122

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“…For example, oxygen-reducing NADH oxidases are present in the cytosol of Entamoeba histolytica (289), Giardia lamblia (278), Trichomonas vaginalis (281,356,489), and Tritrichomonas foetus (78,345). Again, we designate eukaryotes that have no requirement for O 2 in their core energy metabolism "anaerobes," using the term anaerobic to indicate that the organisms in question do not require free O 2 for survival and multiplication.…”

Section: Anaerobes and Microaerophiles: Redox Balance With A Pinch Ofmentioning

confidence: 99%

Biochemistry and Evolution of Anaerobic Energy Metabolism in Eukaryotes

Müller

Mentel

Hellemond

et al. 2012

Microbiol Mol Biol Rev

686

904

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SUMMARY Major insights into the phylogenetic distribution, biochemistry, and evolutionary significance of organelles involved in ATP synthesis (energy metabolism) in eukaryotes that thrive in anaerobic environments for all or part of their life cycles have accrued in recent years. All known eukaryotic groups possess an organelle of mitochondrial origin, mapping the origin of mitochondria to the eukaryotic common ancestor, and genome sequence data are rapidly accumulating for eukaryotes that possess anaerobic mitochondria, hydrogenosomes, or mitosomes. Here we review the available biochemical data on the enzymes and pathways that eukaryotes use in anaerobic energy metabolism and summarize the metabolic end products that they generate in their anaerobic habitats, focusing on the biochemical roles that their mitochondria play in anaerobic ATP synthesis. We present metabolic maps of compartmentalized energy metabolism for 16 well-studied species. There are currently no enzymes of core anaerobic energy metabolism that are specific to any of the six eukaryotic supergroup lineages; genes present in one supergroup are also found in at least one other supergroup. The gene distribution across lineages thus reflects the presence of anaerobic energy metabolism in the eukaryote common ancestor and differential loss during the specialization of some lineages to oxic niches, just as oxphos capabilities have been differentially lost in specialization to anoxic niches and the parasitic life-style. Some facultative anaerobes have retained both aerobic and anaerobic pathways. Diversified eukaryotic lineages have retained the same enzymes of anaerobic ATP synthesis, in line with geochemical data indicating low environmental oxygen levels while eukaryotes arose and diversified.

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“…Subcellular, hydrogenosomal membrane and matrix fractions were assayed for the following enzymes: pyruvate : ferredoxin oxidoreductase, hydrogenase, malate dehydrogenase (decarboxylating), acid phosphatase and NADH oxidase to confirm their purity [6,8]. Protein content was measured by using a dye-binding assay kit (Bio-Rad Labs.…”

Section: Assaymentioning

confidence: 99%

Respiration of Trichomonas vaginalis. Components detected by electron paramagnetic resonance spectroscopy

et al. 1986

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1. Electron paramagnetic resonance (EPR) spectrometry was used to characterise the iron-sulphur clusters present in the human parasite, Trichomonas vaginalis, an aerotolerant anaerobic protozoan which lacks mitochondria.2. From observations of whole cells and subcellular fractions, the majority of the EPR signals are derived from one of the two main terminal respiration sites, the hydrogenosome; fractionation of hydrogenosomes revealed that a large proportion of these signals were associated with the membrane of these organelles.3. Resolution into eight species was achieved by varying the degree of reduction and the temperature of the samples.4. One component, a [2Fe-2S] ferredoxin reducible by pyruvate : ferredoxin oxidoreductase, corresponds to that previously purified, and predominates in spectra scanned at temperatures higher than 45 K. This species (mid-point redox potential -300 k 20 mV) was detected both in a hydrogenosomal membrane fraction and in the matrix fraction derived from broken organelles.5. Another iron-sulphur species (mid-point potential -270 mV) was detectable in both membrane and matrix at temperatures lower than 30 K.6. Four other reduced species were confined to the hydrogenosomal membrane and a fifth was not detected after subfractionation, although it appeared in intact organelles. This species is assumed to be highly unstable.7. Free-radical signals in hydrogenosome-enriched fractions probably arise from flavoprotein semiquinones; no other signals were obtained from the cytosolic fractions incubated with NADH.8. A signal in the oxidised state was observed in the hydrogenosomal membrane. 9. Possible identities of hydrogenosomal iron-sulphur clusters are discussed in relation to previously established enzyme activities.Trichomonads are parasitic protozoa, which ferment carbohydrates and produce organic acids, H2 and C 0 2 . Although their metabolism is primarily anaerobic, they are aerotolerant [I] and have an active respiratory system [2]. The species studied in greatest detail are the cattle parasite Trichomonas foetus and the sexually transmitted human parasite Trichomonas vaginalis. Neither organism has organelles recognisable in electron micrographs as mitochondria Under aerobic conditions the hydrogenosomes of T. foetusCorrespondence to A. Chapman,

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Biochemical Cytology of Trichomonad Flagellates

Cited by 103 publications

References 24 publications

Glycolysis in Trypanosoma brucei

Glycolysis in Trypanosoma brucei

Biochemistry and Evolution of Anaerobic Energy Metabolism in Eukaryotes

Respiration of Trichomonas vaginalis. Components detected by electron paramagnetic resonance spectroscopy

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