Alanine metabolism

The single step synthesis of alanine from pyruvate is unique to Coccidians such as Toxoplasma and Neospora among the phylum of Apicomplexa. This is absent in other groups such as Plasmodium, Theileria and Cryptosporidium species, which utilise alanine from host [1]. Alanine dehydrogenase and alanine transaminase are the enzymes which catalyse this one step conversion. Alanine racemase, a pyridoxal phosphate dependent enzyme which catalyses isomerisation of L-alanine to D-alanine is present in both Plasmodium falciparum and Toxoplasma gondii genomes and annotated to the pyridoxal phosphate metabolism pathway in MPMP as an example of an enzyme that requires pyridoxal phosphate as a cofactor for its function.

 

Enzyme EC Number Gene id Protein localisation Localisation data source
Alanine dehydrogenase 1.4.1.1 TGME49_203500    
Alanine dehydrogenase 1.4.1.1 TGME49_315260    
Alanine transaminase 2.6.1.2 TGME49_264030    
Alanine racemase 5.1.1.1 TGME49_318720    
Alanine-tRNA ligase 6.1.1.7 TGME49_219540 Cytosol Previous publication

 

List of genes annotated as tRNA-Ala in T. gondii genome

 

TGME49_008460 TGME49_008470 TGME49_019560 TGME49_020550
TGME49_053010 TGME49_077250 TGME49_077265 TGME49_097950
TGME49_100644 TGME49_128550    

 

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Sources and fates of metabolites

 

Substrate Source pathways Product Fate pathways
Pyruvate Glycolysis D-alanine ?
Glutamate Glutamate metabolism 2-oxglutarate Tricarboxylic acid (TCA) cycle, Glutamate metabolism