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

version 3 (curated until May 28, 2011)

The antioxidant systems in Toxoplasma gondii and the role of cytosolic catalase in defence against oxidative injury.

Ding, M., Kwok, L. Y., Schluter, D., Clayton, C., Soldati, D. (2004 Jan, Mol Microbiol)

Superoxide dismutase, catalase, glutathione peroxidase and peroxiredoxins form an antioxidant network protecting cells against reactive oxygen species (ROS). Catalase is a potent H2O2-detoxifying enzyme, which is unexpectedly absent in some members of the Kinetoplastida and Apicomplexa, but present in Toxoplasma gondii. In T. gondii, catalase appears to be cytosolic. In addition, T. gondii also possesses genes coding for other types of peroxidases, including glutathione/thioredoxin-like peroxidases and peroxiredoxins. This study presents a detailed analysis of the role of catalase in the parasite and reports the existence of antioxidant enzymes localized in the cytosol and the mitochondrion of T. gondii. The catalase gene was disrupted and, in addition, T. gondii cell lines overexpressing either catalase or a cytosolic 1-cys peroxiredoxin, TgPrx2, under the control of a strong promoter were created. Analysis of these mutants confirmed that the catalase activity is cytosolic and is encoded by a unique gene in T. gondii. Furthermore, the catalase confers protection against H2O2 exposure and contributes to virulence in mice. The overexpression of Prx2 also increases protection against H2O2 treatment, suggesting that catalase and other peroxidases function as a defence mechanism against endogenously produced reactive oxygen intermediates and the oxidative stress imposed by the host.

PubMed: 14651610, full text

Localisation information

TGME49_032250 (Catalase) peroxisomal catalase

Experimental localisation: cytosol during extracellular tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "IFA performed on RHhxpgrt – and RHcat – strains using several anti-catalase antibodies demonstrated consistently that the diffuse cytosolic staining was the only specific labelling that corresponded to the catalase. In contrast, the various punctuated staining patterns observed previously (Ding et al., 2000; Kaasch and Joiner, 2000) persisted in the RHcat– mutant and therefore were unspecific (Fig. 6B)."
  • Microscopy type: Light
  • Microscopy method: polyclonal antibody directly to protein
  • Strain: Rhhxpgrt-
  • Gene model mapping comments: inferred from another publication
  • Localisation record: cytosol during extracellular tachyzoite

TGME49_116330 (SOD2, SODB2) iron-containing superoxide dismutase

Experimental localisation: mitochondrion during intracellular tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "Both transgene products were targeted into the single tubular mitochondrion of T. gondii as demonstrated by indirect immunofluorescence assay (IFA) (Fig. 2B)."
  • Microscopy type: Light
  • Microscopy method: C terminal Ty tag
  • Strain: RH
  • Gene model mapping comments: inferred from another publication
  • Localisation record: mitochondria during intracellular tachyzoite

TGME49_116190 (SOD3, SODB3) superoxide dismutase, putative

Experimental localisation: mitochondrion during intracellular tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "Both transgene products were targeted into the single tubular mitochondrion of T. gondii as demonstrated by indirect immunofluorescence assay (IFA) (Fig. 2B)."
  • Microscopy type: Light
  • Microscopy method: C terminal Ty tag
  • Strain: RH
  • Gene model mapping comments: inferred from another publication
  • Localisation record: mitochondria during intracellular tachyzoite

TGME49_030410 (PRX3, Prx3) peroxiredoxin 3

Experimental localisation: mitochondrion during intracellular tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "Targeting of TgPrx3 to the mitochondrion was determined by double IFA using anti-Ty1 and anti-MLC1 on intracellular tachyzoites stably transformed with the expression plasmid pT8Prx3Ty-HX"
  • Microscopy type: Light
  • Microscopy method: C terminal Ty tag
  • Strain: RH
  • Gene model mapping comments: inferred from another publication
  • Localisation record: mitochondria during intracellular tachyzoite

TGME49_066130 (TPRX2, Prx2) glutathione/thioredoxin peroxidase, putative

Experimental localisation: cytosol during intracellular tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "Expression and cytosolic distribution of Prx2 was confirmed by IFA on intracellular tachyzoites by confocal microscopy."
  • Microscopy type: Light
  • Microscopy method: polyclonal antibody directly to protein
  • Strain: RH
  • Gene model mapping comments: blast from BM039715
  • Localisation record: cytosol during intracellular tachyzoite

TGME49_057680 (MLC1) myosin light chain TgMLC1

Experimental localisation: inner membrane complex during intracellular tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "MLC1 serves as marker of the pellicle of the parasites (Herm-Gotz et al., 2002)."
  • Microscopy type: Light
  • Microscopy method: polyclonal antibody directly to protein
  • Strain: RH
  • Gene model mapping comments: inferred from another publication
  • Localisation record: pellicle during intracellular tachyzoite