ApiLoc - A database of published protein sub-cellular localisation in Apicomplexa

version 3 (curated until May 28, 2011)

Localisation of gluconeogenesis and tricarboxylic acid (TCA)-cycle enzymes and first functional analysis of the TCA cycle in Toxoplasma gondii.

Fleige, T., Pfaff, N., Gross, U., Bohne, W. (2008 Aug, Int J Parasitol)

The apicomplexan parasite Toxoplasma gondii displays some unusual localisations of carbohydrate converting enzymes, which is due to the presence of a vestigial, non-photosynthetic plastid, referred to as the apicoplast. It was recently demonstrated that the single pyruvate dehydrogenase complex (PDH) in T. gondii is exclusively localised inside the apicoplast but absent in the mitochondrion. This raises the question about expression, localisation and function of enzymes for the tricarboxylic acid (TCA)-cycle, which normally depends on PDH generated acetyl-CoA. Based on the expression and localisation of epitope-tagged fusion proteins, we show that all analysed TCA cycle enzymes are localised in the mitochondrion, including both isoforms of malate dehydrogenase. The absence of a cytosolic malate dehydrogenase suggests that a typical malate-aspartate shuttle for transfer of reduction equivalents is missing in T. gondii. We also localised various enzymes which catalyse the irreversible steps in gluconeogenesis to a cellular compartment and examined mRNA expression levels for gluconeogenesis and TCA cycle genes between tachyzoites and in vitro bradyzoites. In order to get functional information on the TCA cycle for the parasite energy metabolism, we created a conditional knock-out mutant for the succinyl-CoA synthetase. Disruption of the sixth step in the TCA cycle should leave the biosynthetic parts of the cycle intact, but prevent FADH2 production. The succinyl-CoA synthetase depletion mutant displayed a 30% reduction in growth rate, which could be restored by supplementation with 2 microM succinate in the tissue culture medium. The mitochondrial membrane potential in these parasites was found to be unaltered. The lack of a more severe phenotype suggests that a functional TCA cycle is not essential for T. gondii replication and for maintenance of the mitochondrial membrane potential.

PubMed: 18336823, full text

Localisation information

TGME49_005380 (Fructose-bisphosphatase I) fructose-1,6-bisphosphatase, putative

Experimental localisation: cytosol during tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "Fructose-bisphosphatase I and II, glucosephosphate-mutase I and II, and PEP-carboxykinase I are localised in the cytosol."
  • Microscopy type: Light
  • Microscopy method: myc tag
  • Strain: RH
  • Gene model mapping comments: taken directly from publication
  • Localisation record: cytosol during tachyzoite

TGME49_047510 (Fructose-bisphosphatase II) fructose-1,6-bisphosphatase, putative

Experimental localisation: cytosol during tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "Fructose-bisphosphatase I and II, glucosephosphate-mutase I and II, and PEP-carboxykinase I are localised in the cytosol."
  • Microscopy type: Light
  • Microscopy method: myc tag
  • Strain: RH
  • Gene model mapping comments: taken directly from publication
  • Localisation record: cytosol during tachyzoite

TGME49_085980 (glucosephosphate-mutase I, PRP1) phosphoglucomutase/parafusin related protein 1, putative

Experimental localisation: cytosol during tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "Fructose-bisphosphatase I and II, glucosephosphate-mutase I and II, and PEP-carboxykinase I are localised in the cytosol."
  • Microscopy type: Light
  • Microscopy method: myc tag
  • Strain: RH
  • Gene model mapping comments: taken directly from publication
  • Localisation record: cytosol during tachyzoite

TGME49_118580 (glucosephosphate-mutase II) phosphoglucomutase, putative

Experimental localisation: cytosol during tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "Fructose-bisphosphatase I and II, glucosephosphate-mutase I and II, and PEP-carboxykinase I are localised in the cytosol."
  • Microscopy type: Light
  • Microscopy method: myc tag
  • Strain: RH
  • Gene model mapping comments: taken directly from publication
  • Localisation record: cytosol during tachyzoite

TGME49_089650 (PEP-carboxykinase I) phosphoenolpyruvate carboxykinase

Experimental localisation: cytosol during tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "Fructose-bisphosphatase I and II, glucosephosphate-mutase I and II, and PEP-carboxykinase I are localised in the cytosol."
  • Microscopy type: Light
  • Microscopy method: myc tag
  • Strain: RH
  • Gene model mapping comments: taken directly from publication
  • Localisation record: cytosol during tachyzoite

TGME49_068890 (CS1, Citrate-synthase I (CS1)) citrate synthase, putative

Experimental localisation: mitochondrion during tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "Table 2. "
  • Microscopy type: Light
  • Microscopy method: myc tag
  • Strain: RH
  • Gene model mapping comments: taken directly from publication
  • Localisation record: Mitochondrion during tachyzoite
  • Comment: EC: 2.3.3.1

TGME49_026730 (ACN/IRP, Aconitase (ACN)) aconitate hydratase, putative

Experimental localisation: mitochondrion during tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "Table 2. "
  • Microscopy type: Light
  • Microscopy method: myc tag
  • Strain: RH
  • Gene model mapping comments: taken directly from publication
  • Localisation record: Mitochondrion during tachyzoite
  • Comment: EC: 4.2.1.3

TGME49_113140 (ICDH2, Isocitrate-dehydrogenase I (IDH1)) isocitrate dehydrogenase, putative

Experimental localisation: mitochondrion during tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "Table 2. "
  • Microscopy type: Light
  • Microscopy method: myc tag
  • Strain: RH
  • Gene model mapping comments: taken directly from publication
  • Localisation record: Mitochondrion during tachyzoite
  • Comment: EC: 1.1.1.42

TGME49_090600 (Succinyl-CoA-synthetase alpha (SCSa)) succinyl-CoA ligase alpha subunit, putative

Experimental localisation: mitochondrion during tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "Table 2. "
  • Microscopy type: Light
  • Microscopy method: myc tag
  • Strain: RH
  • Gene model mapping comments: taken directly from publication, blast from DQ457192, annotation matches
  • Localisation record: Mitochondrion during tachyzoite
  • Comment: EC: 6.2.1.4

TGME49_109750 (Succinyl-CoA-synthetase (ATP) (SCSb)) succinyl-CoA ligase, putative

Experimental localisation: mitochondrion during tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "Table 2. "
  • Microscopy type: Light
  • Microscopy method: myc tag
  • Strain: RH
  • Gene model mapping comments: taken directly from publication
  • Localisation record: Mitochondrion during tachyzoite
  • Comment: EC: 6.2.1.5

TGME49_118430 (Malate-dehydrogenase (MDH)) malate dehydrogenase, putative

Experimental localisation: mitochondrion during tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "Table 2. "
  • Microscopy type: Light
  • Microscopy method: myc tag
  • Strain: RH
  • Gene model mapping comments: taken directly from publication
  • Localisation record: Mitochondrion during tachyzoite
  • Comment: EC: 1.1.1.37

TGME49_088500 (FAD Malate-dehydrogenase (MDH-FAD)) malate:quinone oxidoreductase, putative

Experimental localisation: mitochondrion during tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "Table 2. "
  • Microscopy type: Light
  • Microscopy method: myc tag
  • Strain: RH
  • Gene model mapping comments: taken directly from publication
  • Localisation record: Mitochondrion during tachyzoite
  • Comment: EC: 1.1.99.16