Asparagine and aspartate metabolism

This metabolic pathway is same as the MPMP pathway of asparagine and aspartate metabolism for Plasmodium falciparum. The amino acids asparagine and aspartate are non-essential and de novo synthesised in both Toxoplasma gondii and P. falciparum [1]. The enzyme aspartate transaminase present in this pathway can catalyse reversible conversion of glutamate and oxaloacetate to aspartate and 2-oxoglutarate depending on the availability of amino acids and TCA cycle intermediates. The enzyme asparagine synthase (.6.3.5.4) catalyses conversion of aspartate to asparagine. The enzymes aspartate carbamoyltransferase and adenylosuccinate synthase catalyse synthesis of substrates for pyrimidine biosynthesis, N-carbamoyl-aspartate and adenylosuccinate respectively.

 

Enzyme EC Number Gene id Protein localisation Localisation data source
Aspartate carbamoyltransferase 2.1.3.2 TGME49_291640 Nucleus Previous publication
Aspartate transaminase 2.6.1.1 TGME49_248600 Cytosol Previous publication
Aspartate-tRNA ligase 6.1.1.12 TGME49_202530 Cytosol Previous publication
Asparagine-tRNA ligase 6.1.1.22 TGME49_270510 Cytosol Previous publication
Adenylosuccinate synthase 6.3.4.4 TGME49_279450 Cytosol Previous publication
Asparagine synthase 6.3.5.4 TGME49_253430 Extracellular? Previous publication

 

List of genes annotated as tRNA-Asp in the T. gondii genome

 

TGME49_018430 TGME49_018440 TGME49_050860 TGME49_053505
TGME49_072580 TGME49_100633 TGME49_116460  

 

List of genes annotated as tRNA-Asn in the T. gondii genome

 

TGME49_032460 TGME49_039450 TGME49_093750 TGME49_100645
TGME49_113800      

 

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Sources and fates of metabolites

 

Substrate Source pathways Product Fate pathways
L-Aspartate Host Oxaloacetate Tricarboxylic acid (TCA) cycle
L-Glutamine Glutamate metabolism L-Glutamate Glutamate metabolism
Carbamoylphosphate Nitrogen metabolism N-Carbamoyl-L-aspartate Pyrimidine metabolism
GTP, IMP Purine metabolism Adenylosuccinate Purine metabolism
2-oxoglutarate Pyruvate metabolism, Tricarboxylic acid (TCA) cycle L-Glutamate Glutamate metabolism