Glutamate and glutamine are non-essential amino acids in both Toxoplasma gondii and Plasmodium falciparum as in humans, whereas glutamate is an essential amino acid utilised from host in Cryptosporidium species. This is because the 2-oxoglutarate, the TCA cycle intermediate required for glutamate synthesis cannot be synthesised as the TCA cycle enzymes are missing in most of Cryptosporidium species. Although Cryptosporidium muris possess TCA cycle, the enzymes glutamate dehydrogenase and aspartate transaminase involved in glutamate synthesis are absent in the Cryptosporidum species. The ecological niches of gastric glands of stomach for C. muris and epithelial cells of small intestine for Cryptosporidium parvum and Cryptosporidium hominis provide them with the advantage of their ability to fulfil amino acid requirements from the host. These species possess the enzyme, glutamate-ammonia ligase and therefore can de novo synthesise glutamine. Cryptosporidia possess the capability to de novo synthesise proline from glutamate as in humans and in T. gondii . The genes for all the enzymes involved in this process are present in C. parvum gene models.
|Enzyme||EC Number||Gene id|
|L-glutamate ammonia ligase||188.8.131.52||cgd6_4570|
List of genes annotated as tRNA-Glu in C. parvum genome
List of genes annotated as tRNA-Gln in C. parvum genome
Sources and fates of metabolic pathways
|Substrate||Source pathways||Product||Fate pathways|