Polyamine salvage

A metabolic capability that is present in Plasmodium falciparum and absent in Toxoplasma gondii 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 Coccidia, it has been demonstrated that T. gondii can synthesise putrescine from host spermine in backward reactions. It was also shown that arginine from the 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 Neospora caninum genomes. Other enzymes biochemically shown to be involved in arginine and spermine metabolism such as arginine deiminase and ornithine carbamoyltransferase are not yet identified in the genome. 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 is not included as the enzymes are missing in the genome.

 

Enzyme

EC Number Gene id Protein localisation Localisation data source
N1-acetylpolyamine oxidase 1.5.3.13 TGME49_242415 Cytosol Previous publication
N1-acetylpolyamine oxidase 1.5.3.13 TGME49_275420    
Diamine N-acetyltransferase (spermidine/spermine N1-acetyltransferase) 2.3.1.57 TGME49_243600 Cytosol Previous publication

 

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Sources of metabolites

 

Substrate Source pathways
Spermine Host