Lysine metabolism

Lysine is an essential amino acid in most Apicomplexa species as in humans and need to be utilised from host. The exception to this is the cyst forming Coccidians such as Toxoplasma gondii and Neospora caninum. The Cryptosporidia species possess the gene for the enzyme saccharopine dehydrogenase which converts lysine to saccharopine which can be degraded to 2-oxodipate in the host. The other enzymes involved in lysine degradation in Plasmodia and cyst forming Coccidia are absent in Cryptosporidia. This pathway also includes large number of genes coding histone-lysine N-methyltransferase which catalyses protein methylation.

 

Enzyme EC Number Gene id
Saccharopine dehydrogenase 1.5.1.7 CMU_012840
Histone-lysine N-methyltransferase 2.1.1.43 CMU_001080
Histone-lysine N-methyltransferase 2.1.1.43 CMU_012480
Histone-lysine N-methyltransferase 2.1.1.43 CMU_016340
Histone-lysine N-methyltransferase 2.1.1.43 CMU_028930
Histone-lysine N-methyltransferase 2.1.1.43 CMU_032930
Acylaminoacyl-peptidase 3.4.19.1 CMU_037730
Lysine-tRNA ligase 6.1.1.6 CMU_017360

 

List of genes annotated as tRNA-Lys in C. muris genome

 

CMU_025510 CMU_035620

 

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Sources and fates of metabolites

 

Substrate Source pathways Product Fate pathways
Lysine Host Saccharopine Host?