Asparagine and aspartate metabolism

The asparagine and aspartate metabolism pathway for Neospora caninum is same as the pathway for Toxoplasma gondii and MPMP pathway for Plasmodium falciparum. The amino acids asparagine and aspartate are non-essential and de novo synthesised in both T. 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 the 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. All these enzymes present in T. gondii and P. falciparum are aslo present in N. caninum genome.

 

Enzyme EC Number Gene id
Aspartate carbamoyltransferase 2.1.3.2 NCLIV_043140
Aspartate transaminase 2.6.1.1 NCLIV_064760
Aspartate-tRNA ligase 6.1.1.12 NCLIV_022400
Asparagine-tRNA ligase 6.1.1.22 NCLIV_036250
Adenylosuccinate synthase 6.3.4.4 NCLIV_038330
Asparagine synthase 6.3.5.4 NCLIV_007860

 

List of genes annotated as tRNA-Asp in N. caninum genome

 

NC_LIV_tRNA_040005 NC_LIV_tRNA_100008 NC_LIV_tRNA_130011 NC_LIV_tRNA_140004
NC_LIV_tRNA_140005 NC_LIV_tRNA_140012    

 

List of genes annotated as tRNA-Asn in N. caninum genome

 

NC_LIV_tRNA_010001 NC_LIV_tRNA_010002 NC_LIV_tRNA_010003 NC_LIV_tRNA_070004
NC_LIV_tRNA_100004 NC_LIV_tRNA_130008    

 

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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