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 |
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 |
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