Polyamine salvage

A metabolic capability which is present in Plasmodium falciparum and absent in the Coccidians Toxoplasma gondii , Neospora caninum and Cryptosporidium species is the synthesis of polyamines such as spermine and spermidine. This has been incorporated with methionine metabolism in MPMP (methionine and polyamine metabolism). Although polyamine biosynthesis from arginine is absent in the Coccidians, it has been demonstrated that T. gondii can synthesise putrescine from host spermine in backward reactions. It was also shown that arginine from host can be metabolised to ornithine and carbamoyl phosphate [1]. Polyamine oxidase and spermidine N-acetyltransferase (SAT), spermine/spermidine N-acetyltransferase (SSAT) enzymes are present in T. gondii and N. caninum genomes. Other enzymes biochemically shown to be involved in arginine and spermine metabolism in T. gondii such as arginine deiminase and ornithine carbamoyltransferase are not yet identified in either genomes. Here the pathway of polyamine salvage is reconstructed to show the back conversion of putrescine from spermine salvaged from host. The arginine metabolism biochemically detected in T. gondii is not included for both T. gondii and N. caninum pathways as these enzymes are missing in both the genomes.

 

Enzyme EC Number Gene id
N1-acetylpolyamine oxidase 1.5.3.13 NCLIV_017570
N1-acetylpolyamine oxidase 1.5.3.13 NCLIV_052860
Diamine N-acetyltransferase (spermidine/spermine N1-acetyltransferase) 2.3.1.57 NCLIV_018320

 

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Sources of metabolites

 

Substrate Source pathways
Spermine Host