Pathway · 5 proteins
Thiamine metabolism
Proteins of this group that KEGG places on its “Thiamine metabolism” map for Aquifex aeolicus.
How it works
This map shows how thiamine (vitamin B1) is built from two separately made halves, a pyrimidine and a thiazole, which are then joined. The proteins here make the pyrimidine half, through one of the most complex rearrangements known, and the thiazole half, including the deoxyxylulose phosphate that the thiazole is built from.
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 |
|---|---|---|---|---|---|
| Phosphomethylpyrimidine synthase | 4.1.99.17 | 5-amino-1-(5-phospho-beta-D-ribosyl)imidazole + S-adenosyl-L-methionine = 4-amino-2-methyl-5-(phosphooxymethyl)pyrimidine + CO + 5'-deoxyadenosine + formate + L-methionine + 3 H(+) | Zn(2+), [4Fe-4S] cluster | 457 | Step named |
| Hydroxymethylpyrimidine/phosphomethylpyrimidine kinase | 2.7.1.49; 2.7.4.7 | 4-amino-5-hydroxymethyl-2-methylpyrimidine + ATP = 4-amino-2-methyl-5-(phosphooxymethyl)pyrimidine + ADP + H(+) | — | 255 | Step named |
| Thiazole synthase | 2.8.1.10 | [ThiS sulfur-carrier protein]-C-terminal-Gly-aminoethanethioate + 2-iminoacetate + 1-deoxy-D-xylulose 5-phosphate = [ThiS sulfur-carrier protein]-C-terminal Gly-Gly + 2-[(2R,5Z)-2-carboxy-4-methylthiazol-5(2H)-ylidene]ethyl phosphate + 2 H2O + H(+) | 1-deoxy-D-xylulose 5-phosphate | 267 | Step named |
| FAD dependent oxidoreductase domain-containing protein | — | — | — | 353 | Step named |
| 1-deoxy-D-xylulose-5-phosphate synthase | 2.2.1.7 | D-glyceraldehyde 3-phosphate + pyruvate + H(+) = 1-deoxy-D-xylulose 5-phosphate + CO2 | Mg(2+) | 628 | 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 |
|---|---|---|---|---|---|
| Adenylate kinaseHome: Interconversion and salvage | 2.7.4.3 | AMP + ATP = 2 ADP | — | 206 | Step named |
| Thiamine-monophosphate kinaseHome: Thiamine and pyridoxal | 2.7.4.16 | thiamine phosphate + ATP = thiamine diphosphate + ADP | Mg(2+) | 306 | Step named |
| Thiamine-phosphate synthase 1Home: Thiamine and pyridoxal | 2.5.1.3 | 2-[(2R,5Z)-2-carboxy-4-methylthiazol-5(2H)-ylidene]ethyl phosphate + 4-amino-2-methyl-5-(diphosphooxymethyl)pyrimidine + 2 H(+) = thiamine phosphate + CO2 + diphosphate | Mg(2+) | 215 | Step named |
| cysteine desulfuraseHome: Not yet placed in a pathway | 2.8.1.7 | — | — | 370 | Step named |
| Nucleoside-triphosphatase THEP1Home: Purine metabolism | 3.6.1.15 | a ribonucleoside 5'-triphosphate + H2O = a ribonucleoside 5'-diphosphate + phosphate + H(+) | — | 178 | Unspecified |
Origins
Could thiamine pyrophosphate have been supplied before this pathway existed?
Essential coenzymes have not been convincingly made under simulated prebiotic conditions, and the books searched describe no prebiotic route to thiamine.
Thiamine pyrophosphate is required by enzymes at the centre of carbon metabolism, such as the 2-oxoglutarate dehydrogenase complex.
Its supply is controlled by the most widespread riboswitch known: when enough is present, it binds the messenger RNA and stops more being made.
From the books: Garrett & Grisham, Biochemistry, p. 665; Koonin & Galperin, Sequence – Evolution – Function, PDF p. 337; Nelson & Cox, Lehninger Principles of Biochemistry, p. 1133.
The wider question for this part of the cell: origins for manufacturing cofactors and vitamins.
Sources
- KEGG map aae00730 (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 · 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