A metabolic capability which is present in Plasmodium falciparum and absent in Coccidia including Cryptosporidia is the synthesis of polyamines such as spermine and spermidine. This has been incorporated with methionine metabolism in MPMP (methionine and polyamine metabolism). The genes coding for the enzymes ornithine decarboxylase, arginine decarboxylase and spermine/spermidine synthase are absent in the genomes of Cryptosporidia. Polyamine oxidase and spermine/spermidine N-acetyltransferase (SSAT) enzymes are present in Cryptosporidia genomes as in other Coccidia. The activities of arginine decarboxylase, spermine N-acetyltransferase and spermidine N-acetyltransferase were detected in Cryptosporidium parvum extracts although ornithine decarboxylase was not experimentally detected [1, 2]. This suggests the occurrence of back conversion of putrescine from spermine salvaged from host. Although arginine decarboxylase activity was detected and the bacterial pathway for putrescine synthesis from arginine is suggested to be present , this metabolic capability was not added to this pathway as the genes coding for both of the enzymes of this branch of pathway, arginine decarboxylase and agmatine iminohydrolase are missing in gene models.
|Enzyme||EC Number||Gene id|
|Diamine N-acetyltransferase (spermidine/spermine N1-acetyltransferase)||18.104.22.168||cgd4_4000|