Pathway · 4 proteins
Biotin metabolism
Proteins of this group that KEGG places on its “Biotin metabolism” map for Aquifex aeolicus.
How it works
This map shows how biotin is made from pimelate, a seven-carbon acid, and alanine. The proteins here activate pimelate with coenzyme A, join it to alanine, and move an amino group using SAM; later enzymes close the rings of biotin.
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 |
|---|---|---|---|---|---|
| 6-carboxyhexanoate--CoA ligase | 6.2.1.14 | heptanedioate + ATP + CoA = 6-carboxyhexanoyl-CoA + AMP + diphosphate | Mg(2+) | 240 | Step named |
| Adenosylmethionine-8-amino-7-oxononanoate aminotransferase | 2.6.1.62 | (8S)-8-amino-7-oxononanoate + S-adenosyl-L-methionine = S-adenosyl-4-methylsulfanyl-2-oxobutanoate + (7R,8S)-7,8-diammoniononanoate | — | 453 | Step named |
| AB hydrolase-1 domain-containing protein | — | — | — | 207 | Step named |
| Putative 8-amino-7-oxononanoate synthase | 2.3.1.47 | 6-carboxyhexanoyl-[ACP] + L-alanine + H(+) = (8S)-8-amino-7-oxononanoate + holo-[ACP] + CO2 | — | 373 | 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 |
|---|---|---|---|---|---|
| ATP-dependent dethiobiotin synthetase BioDHome: Biotin and lipoate | 6.3.3.3 | (7R,8S)-7,8-diammoniononanoate + CO2 + ATP = (4R,5S)-dethiobiotin + ADP + phosphate + 3 H(+) | Mg(2+) | 220 | Step named |
| biotin--[biotin carboxyl-carrier protein] ligaseHome: Biotin and lipoate | 6.3.4.15 | biotin + L-lysyl-[protein] + ATP = N(6)-biotinyl-L-lysyl-[protein] + AMP + diphosphate + H(+) | — | 233 | Step named |
| Biotin synthaseHome: Biotin and lipoate | 2.8.1.6 | (4R,5S)-dethiobiotin + (sulfur carrier)-SH + 2 reduced [2Fe-2S]-[ferredoxin] + 2 S-adenosyl-L-methionine = (sulfur carrier)-H + biotin + 2 5'-deoxyadenosine + 2 L-methionine + 2 oxidized [2Fe-2S]-[ferredoxin] | [4Fe-4S] cluster, [2Fe-2S] cluster | 332 | Step named |
| 3-hydroxyacyl-[acyl-carrier-protein] dehydratase FabZHome: Fatty-acid elongation | 4.2.1.59 | a (3R)-hydroxyacyl-[ACP] = a (2E)-enoyl-[ACP] + H2O | — | 150 | Step named |
| Enoyl-[acyl-carrier-protein] reductase [NADH] FabIHome: Fatty-acid elongation | 1.3.1.9 | a 2,3-saturated acyl-[ACP] + NAD(+) = a (2E)-enoyl-[ACP] + NADH + H(+) | — | 270 | Step named |
| 3-oxoacyl-[acyl-carrier-protein] reductase FabGHome: Fatty acid biosynthesis | 1.1.1.100 | a (3R)-hydroxyacyl-[ACP] + NADP(+) = a 3-oxoacyl-[ACP] + NADPH + H(+) | — | 248 | Step named |
| 3-oxoacyl-[acyl-carrier-protein] synthase 2Home: Fatty-acid elongation | 2.3.1.179 | (9Z)-hexadecenoyl-[ACP] + malonyl-[ACP] + H(+) = 3-oxo-(11Z)-octadecenoyl-[ACP] + holo-[ACP] + CO2 | — | 415 | Step named |
Origins
Could biotin have been supplied before this pathway existed?
The books searched describe no prebiotic route to biotin.
Biotin works only when it is attached to a carrier protein, which a separate enzyme loads with carbon dioxide using ATP. Koonin and Galperin note that some organisms use biotin without any known route to make it, a sign that parts of this chemistry are still unknown.
From the books: Zubay, Origins of Life on Earth and in the Cosmos, p. 336; Koonin & Galperin, Sequence – Evolution – Function, PDF p. 369.
The wider question for this part of the cell: origins for manufacturing cofactors and vitamins.
Sources
- KEGG map aae00780 (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 · Folate biosynthesis · Oxidative phosphorylation · Thiamine metabolism · Pantothenate and CoA biosynthesis · Glycine, serine and threonine metabolism · Riboflavin metabolism · Nicotinate and nicotinamide metabolism · Cysteine and methionine metabolism · Porphyrin metabolism · Pyruvate metabolism · Not yet placed in a pathway