If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.
Locations of Mapped Genes:
|Superclasses:||Biosynthesis → Cofactors, Prosthetic Groups, Electron Carriers Biosynthesis → Tetrapyrrole Biosynthesis|
Pathway Summary from MetaCyc:
Tetrapyrroles are compounds whose molecules have four rings of the pyrrole type, generally linked together by single-atom bridges between the alpha positions of the five-membered pyrrole rings. Tetrapyrroles function as a metal-binding cofactor in many important enzymes, proteins and pigments, such as heme, chlorophyll, cobalamine (vitamin B12), siroheme, and cofator F430. The biosynthesis of all of these cofactors start in a similar manner, with the production of the intermediate uroporphyrinogen-III. This intermediate is an important branch point: its methylation directs it toward siroheme, cobalamin or cofactor F430 synthesis, while decarboxylation directs it toward the synthesis of heme and chlorophyll [Phillips03a].
The tetrapyrrole biosynthetic pathway shown here, which starts with glutamate, is found in plants, many bacteria (including Escherichia coli), and the archaea. A second tetrapyrrole biosynthetic pathway, which is found in animals, fungi, certain protozoans, and members of the α-proteobacteria, starts with glycine and succinyl-coA (see tetrapyrrole biosynthesis II (from glycine)). Interestingly, both pathways are present in the chloroplast-containing protozoan Euglena gracilis.
Regardless whether the starting point is glycine or glutamate, both pathways converge at the intermediate 5-aminolevulinate and proceed through the important intermediate uroporphyrinogen-III, which is a major branch point that leads to biosynthesis of different tetrapyrrole compounds, such as the corrinoid cobalamine (vitamin B12) (see MetaCyc pathway adenosylcobalamin biosynthesis II (late cobalt incorporation)), the methanogenic coenzyme F430 (see factor 430 biosynthesis), siroheme (see siroheme biosynthesis, and heme D.
Superpathways: superpathay of heme biosynthesis from glutamate
Pathway Evidence Glyph:
Cantoni84: Cantoni L, Dal Fiume D, Ruggieri R (1984). "Decarboxylation of uroporphyrinogen I and III in 2,3,7,8-tetrachlorodibenzo-p-dioxin induced porphyria in mice." Int J Biochem 16(5);561-5. PMID: 6724109
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