Ubiquinone metabolism

Ubiquinone, also known as coenzyme Q is an integral component of electron transport chain. In electron transport chain of inner mitochondrial membrane, ubiquinone acts as an electron carrier transferring electrons from NADH dehydrogenase (complex I) and succinate dehydrogenase (complex II) to cytochrome bc1 complex (complex III). Ubiquinone is synthesised from chorimsate, end product of shikimate pathway in nine enzyme-catalysed reactions. The other important co-substrates involved in this pathway are glutamine, isoprenoids (terpenoid metabolism) and S-adenosyl methionine (methionine metabolism). This pathway is identical between Toxoplasma gondii and Plasmodium falciparum and the enzymes missing in the genomes of both species are oxo-acid lyase and 3-octaprenyl-4-hydroxybenzoate carboxy-lyase.


Protein EC Number Gene id Protein localisation Localisation data source
FAD-dependent monooxygenase (Ubiquinone biosynthesis monooxygenase) 1.14.13.- TGME49_232540 Mitochondria Previous publication
UbiB Hydroxylase (2-octaprenylphenol hydroxylase) 1.14.13.- TGME49_246600 Mitochondrion Previous publication
Ubiquinone/menaquinone biosynthesis methyltransferase 2.1.1.- TGME49_247920    
Ubiquinone/menaquinone biosynthesis methyltransferase 2.1.1.- TGME49_255670    
Ubiquinone/menaquinone biosynthesis methyltransferase 2.1.1.- TGME49_295690    
3-demethylubiquinone-9 3-O-methyltransferase TGME49_249010 Nucleus Previous publication
3-demethylubiquinone-9 3-O-methyltransferase TGME49_266850    
p-hydroxybenzoate-polyprenyltransferase 2.5.1.- TGME49_259130    
3-octaprenyl-4-hydroxybenzoate carboxy-lyase 4.1.1.- Missing in annotation    
Oxo-acid  lyase 4.3.1.- Missing in annotation    
ABC1 protein required for ubiquinone biosynthesis none TGME49_203940 Nucleus Previous publication
Coq4 none TGME49_275980    


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Sources and fates of metabolites


Substrate Source pathways Product Fate pathways
Chorismate Shikimate biosynthesis Pyruvate Pyruvate metabolism, Alanine metabolism
Glutamine Glutamate metabolism Glutamate Glutamate metabolism
All-trans-Geranyl-Geranyl-PP Terpenoid metabolism    
S-adenosylmethionine Methionine metabolism S-adenosylhomocysteine Methionine metabolism