Redox metabolism

Redox metabolism pathway of Coccidians, Toxoplasma gondii and Neospora caninum is similar to the redox metabolism pathway of Plasmodium falciparum in MPMP. This pathway shows the series of oxidation/reduction activities involved in removal of oxidative radicals such as superoxide anions, hydrogen peroxide and other toxic nucleophiles produced from different metabolic reactions. These reactive oxygen species cause oxidative damage to DNA, lipids and proteins. There are several antioxidant systems present in cells to protect them from these damages. This includes enzymes such as superoxide dismutase which reduces superoxide anion to H2O2 and catalase which reduces H2O2 to water and oxygen. The enzyme peroxiredoxin also reduces H2O2. The oxidised peroxiredoxin can be reduced back by thiols such as glutathione and thioredoxin. The glutathione system consists of glutathione and the enzymes glutathione peroxidase, glutathione reductase and glutathione S-transferase [1]. Glutathione is a tripeptide of glutamine-cysteine-glycine and synthesised de novo in two reactions steps. This glutathione synthesis is also included in this pathway. Glutathione peroxidase and glutathione S-transferase catalyse reduction of oxidative radicals by oxidising glutathione. Glutathione can be reduced back by glutathione reductase [1]. Another redox protein thioredoxin is important in reduction of ribonucleotides to deoxyribonucleotides and its partner thioredoxin reductase catalyses reduction of oxidised thioredoxin using NADPH as electron donor.

 

Enzyme EC Number Gene id Protein localisation Localisation data source
Peroxiredoxin 1.11.1.15 TGME49_217890 Cytosol Previous publication
Peroxiredoxin 1.11.1.15 TGME49_230410 Mitochondrion Apiloc; Previous publication
Peroxiredoxin 1.11.1.15 TGME49_286630 Mitochondrion Previous publication
Peroxiredoxin 1.11.1.15 TGME49_309210 Cytosol Previous publication
Catalase 1.11.1.6 TGME49_232250 Cytosol; Peroxisome Apiloc; Previous publication
Glutathione peroxidase 1.11.1.9 TGME49_266120 Apicoplast Apiloc; Previous publication
Glutathione peroxidase 1.11.1.9 TGME49_266130 Cytosol Apiloc
Superoxide dismutase (Mn) 1.15.1.1 TGME49_316190 Mitochondrion Apiloc
Superoxide dismutase (Fe) 1.15.1.1 TGME49_316310 Cytosol Previous publication
Superoxide dismutase (Fe) 1.15.1.1 TGME49_316330 Mitochondrion, Apicoplast; Extracellular? Apiloc; Previous publication
Ribonucleotide reductase 1.17.4.1 TGME49_207060 Cytosol Previous publication
Ribonucleotide reductase 1.17.4.1 TGME49_294640 Apical complex Previous publication
Glutathione reductase 1.8.1.7 TGME49_219130    
Glutathione reductase 1.8.1.7 TGME49_246920 Mitochondion Previous publication
Thioredoxin reductase 1.8.1.9 TGME49_309730 Cytosol Previous publication
Glutathione S-transferase 2.5.1.18 TGME49_285920    
gamma-Glutamylcysteine synthetase 6.3.2.2 TGME49_232590    
Glutathione synthase 6.3.2.3 TGME49_226800    
Thioredxin none TGME49_216510    
Thioredxin none TGME49_225790 Cytosol Previous publication
Glutaredoxin none TGME49_227100    
Glutaredoxin none TGME49_227150    
Thioredxin none TGME49_232410 Cytosol Previous publication
Glutaredoxin none TGME49_238070 Cytosol Previous publication
Glutaredoxin none TGME49_247580 Apicoplast Previous publication
Thioredxin none TGME49_266620 Extracellular Previous publication
Glutaredoxin none TGME49_268730    
Thioredxin none TGME49_270120 Mitochondrion Apiloc; Previous publication
Thioredxin none TGME49_270140    
Glutaredoxin none TGME49_279400    
Thioredxin none TGME49_289180    
Thioredxin none TGME49_290260 Cytosol Previous publication
Thioredxin none TGME49_291810    
Thioredxin none TGME49_293870 Cytosol Previous publication
MRP and/or GSSG pumps none TGME49_305590 Plasma membrane Previous publication; GO annotation
Thioredxin none TGME49_308050