Pathway · 9 proteins
Folate biosynthesis
Proteins of this group that KEGG places on its “Folate biosynthesis” map for Aquifex aeolicus.
How it works
This map shows how folate, the carrier of single carbon atoms, is made from GTP, para-aminobenzoic acid and glutamate. The proteins here open the GTP ring, build the pterin and join it to para-aminobenzoate. The same starting reaction also feeds queuosine, a modified base in transfer RNA, and some proteins on this page make it.
Grouped by KEGG pathway map. The explanation above is the atlas’s own; the map itself covers more organisms than Aquifex.
Its proteins
| Protein | EC | Reaction (UniProt) | Metal or cluster | Amino acids | Certainty |
|---|---|---|---|---|---|
| Putative pterin-4-alpha-carbinolamine dehydratase | 4.2.1.96 | (4aS,6R)-4a-hydroxy-L-erythro-5,6,7,8-tetrahydrobiopterin = (6R)-L-erythro-6,7-dihydrobiopterin + H2O | — | 99 | Step named |
| Dihydropteroate synthase | 2.5.1.15 | (7,8-dihydropterin-6-yl)methyl diphosphate + 4-aminobenzoate = 7,8-dihydropteroate + diphosphate | Mg(2+) | 399 | Step named |
| Aminodeoxychorismate lyase | — | — | — | 245 | Step named |
| 2-amino-4-hydroxy-6-hydroxymethyldihydropteridine pyrophosphokinase | 2.7.6.3 | 6-hydroxymethyl-7,8-dihydropterin + ATP = (7,8-dihydropterin-6-yl)methyl diphosphate + AMP + H(+) | — | 160 | Step named |
| 7-carboxy-7-deazaguanine synthase | 4.3.99.3 | 6-carboxy-5,6,7,8-tetrahydropterin + H(+) = 7-carboxy-7-carbaguanine + NH4(+) | [4Fe-4S] cluster, Mg(2+) | 219 | Step named |
| GTP cyclohydrolase 1 | 3.5.4.16 | GTP + H2O = 7,8-dihydroneopterin 3'-triphosphate + formate + H(+) | Zn(2+) | 184 | Step named |
| Riboflavin biosynthesis protein RibBA | 3.5.4.25; 4.1.99.12 | D-ribulose 5-phosphate = (2S)-2-hydroxy-3-oxobutyl phosphate + formate + H(+) | D-ribulose 5-phosphate, Mg(2+), Zn(2+) | 406 | Step named |
| 7-cyano-7-deazaguanine synthase | 6.3.4.20 | 7-carboxy-7-carbaguanine + NH4(+) + 2 ATP = 7-cyano-7-carbaguanine + 2 AMP + 2 diphosphate + 2 H(+) | Zn(2+) | 218 | Step named |
| NADPH-dependent 7-cyano-7-deazaguanine reductase | 1.7.1.13 | 7-aminomethyl-7-carbaguanine + 2 NADP(+) = 7-cyano-7-carbaguanine + 2 NADPH + 3 H(+) | — | 129 | Step named |
Also part of this pathway
These proteins are described under another pathway, but also take part here.
| Protein | EC | Reaction (UniProt) | Metal or cluster | Amino acids | Certainty |
|---|---|---|---|---|---|
| p-aminobenzoate synthetaseHome: Aromatic amino acids | — | — | — | 348 | Step named |
| tetrahydrofolate synthaseHome: Folate and pterin chemistry | 6.3.2.17 | (6S)-5,6,7,8-tetrahydrofolyl-(gamma-L-Glu)(n) + L-glutamate + ATP = (6S)-5,6,7,8-tetrahydrofolyl-(gamma-L-Glu)(n+1) + ADP + phosphate + H(+) | Mg(2+) | 410 | Step named |
| 6-carboxy-5,6,7,8-tetrahydropterin synthaseHome: Folate and pterin chemistry | 4.1.2.50 | 7,8-dihydroneopterin 3'-triphosphate + H2O = 6-carboxy-5,6,7,8-tetrahydropterin + triphosphate + acetaldehyde + 2 H(+) | Zn(2+) | 162 | Step named |
Origins
Could folate have been supplied before this nine-protein pathway existed?
None of the books searched describes a prebiotic route to folate.
Bacteria make folate from a pterin, para-aminobenzoic acid and glutamate; mammals cannot make it at all. Sulfa drugs, first found by Gerhard Domagk, block this pathway, and without folate a cell cannot make the precursors of DNA and RNA.
Nine proteins of the minimal set serve this pathway.
From the books: Slonczewski & Foster, Microbiology, p. 1105.
The wider question for this part of the cell: origins for manufacturing cofactors and vitamins.
Sources
- KEGG map aae00790 (enzymes of this organism highlighted)
Other pathways in this group: Heme and quinones · Biotin and lipoate · NAD and flavins · Thiamine and pyridoxal · Folate and pterin chemistry · Lipid and cofactor connections · Coenzyme A · Aspartate-family branches · Amino-acid connections · Folate-linked carbon transfer · Serine, glycine and sulfur · Oxidative phosphorylation · Thiamine metabolism · Pantothenate and CoA biosynthesis · Glycine, serine and threonine metabolism · Riboflavin metabolism · Nicotinate and nicotinamide metabolism · Biotin metabolism · Cysteine and methionine metabolism · Porphyrin metabolism · Pyruvate metabolism · Not yet placed in a pathway