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), malate:quinone oxidoreductase and succinate dehydrogenase (complex II) to cytochrome bc1 complex (complex III). Ubiquinone is synthesised from chorimsate, which is salvaged from host as shikimate pathway is absent. The other important co-substrates involved in this pathway are glutamine, isoprenoids (terpenoid metabolism) and S-adenosyl methionine (methionine metabolism). This pathway is identical in Toxoplasma, Plasmodia, Cryptosporidia and Piroplasma species and two enzymes, oxo-acid lyase and 3-octaprenyl-4-hydroxybenzoate carboxy-lyase are missing in the genomes of all apicomplexan species.
Enzyme | EC Number | Gene id |
---|---|---|
UbiB Hydroxylase (2-octaprenylphenol hydroxylase) | 1.14.13.- | TA12685 |
FAD-dependent monooxygenase (Ubiquinone biosynthesis monooxygenase) | 1.14.13.- | TA15760 |
Ubiquinone/menaquinone biosynthesis methyltransferase | 2.1.1.- | TA04405 |
Ubiquinone/menaquinone biosynthesis methyltransferase | 2.1.1.- | TA09885 |
3-demethylubiquinone-9 3-O-methyltransferase | 2.1.1.64 | TA11825 |
p-hydroxybenzoate-polyprenyltransferase | 2.5.1.- | TA18290 |
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 | TA19900 |
Sources and fates of metabolites
Substrate | Source pathways | Product | Fate pathways |
---|---|---|---|
Chorismate | Host | Pyruvate | Pyruvate metabolism |
Glutamine | Host | Glutamate | Glutamate metabolism |
All-trans-Geranyl-Geranyl-PP | Terpenoid metabolism | ||
S-adenosylmethionine | Methionine metabolism | S-adenosylhomocysteine | Methionine metabolism |
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