Pathway · 5 proteins
Amino sugar and nucleotide sugar metabolism
Proteins of this group that KEGG places on its “Amino sugar and nucleotide sugar metabolism” map for Aquifex aeolicus.
How it works
This map covers sugars that carry an amino group, and sugars attached to a nucleotide carrier such as UDP or GDP. The nucleotide carrier activates a sugar so it can be added to a growing chain. The proteins here make and reshape UDP-glucose, its oxidised and flipped forms, and GDP-mannose: the activated sugars used to build the cell surface.
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 |
|---|---|---|---|---|---|
| UDP-glucose 6-dehydrogenase | 1.1.1.22 | UDP-alpha-D-glucose + 2 NAD(+) + H2O = UDP-alpha-D-glucuronate + 2 NADH + 3 H(+) | — | 437 | Step named |
| UDP-glucose 4-epimerase | 5.1.3.2 | UDP-alpha-D-glucose = UDP-alpha-D-galactose | — | 327 | Step named |
| UTP--glucose-1-phosphate uridylyltransferase | 2.7.7.9 | alpha-D-glucose 1-phosphate + UTP + H(+) = UDP-alpha-D-glucose + diphosphate | — | 297 | Step named |
| mannose-1-phosphate guanylyltransferase | 2.7.7.13 | alpha-D-mannose 1-phosphate + GTP + H(+) = GDP-alpha-D-mannose + diphosphate | — | 453 | Step named |
| Mannose-1-phosphate guanyltransferase | — | — | — | 831 | 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 |
|---|---|---|---|---|---|
| Bifunctional phosphoglucose/phosphomannose isomeraseHome: Glycolysis / Gluconeogenesis | 5.3.1.8; 5.3.1.9 | alpha-D-glucose 6-phosphate = beta-D-fructose 6-phosphate | D-fructose 6-phosphate | 320 | Step named |
| Glutamine--fructose-6-phosphate aminotransferase [isomerizing]Home: Not yet placed in a pathway | 2.6.1.16 | D-fructose 6-phosphate + L-glutamine = D-glucosamine 6-phosphate + L-glutamate | — | 592 | Step named |
| Bifunctional protein GlmUHome: Not yet placed in a pathway | 2.3.1.157; 2.7.7.23 | alpha-D-glucosamine 1-phosphate + acetyl-CoA = N-acetyl-alpha-D-glucosamine 1-phosphate + CoA + H(+) | Mg(2+) | 464 | Step named |
| UDP-N-acetylglucosamine 1-carboxyvinyltransferaseHome: Peptidoglycan precursors | 2.5.1.7 | phosphoenolpyruvate + UDP-N-acetyl-alpha-D-glucosamine = UDP-N-acetyl-3-O-(1-carboxyvinyl)-alpha-D-glucosamine + phosphate | — | 425 | Step named |
| UDP-N-acetylenolpyruvoylglucosamine reductaseHome: Peptidoglycan precursors | 1.3.1.98 | UDP-N-acetyl-alpha-D-muramate + NADP(+) = UDP-N-acetyl-3-O-(1-carboxyvinyl)-alpha-D-glucosamine + NADPH + H(+) | — | 297 | Step named |
| Nucleotide sugar epimeraseHome: Not yet placed in a pathway | — | — | — | 321 | Unspecified |
Origins
How could amino sugars and nucleotide-linked sugars have formed before cells?
How it was discovered
- 2004The glmS ribozyme is found in bacteria: an RNA that cuts itself only when glucosamine-6-phosphate binds to it.Atkins, Gesteland & Cech (eds.), RNA Worlds, p. 101 (Winkler et al. 2004)
None of the books searched describes a prebiotic route to amino sugars or nucleotide sugars.
In many bacteria the supply of amino sugars is controlled by an RNA switch, the glmS ribozyme. Without glucosamine-6-phosphate it is no faster than background hydrolysis; once that metabolite binds, cutting speeds up as much as ten-million-fold. The product of the pathway controls the pathway's own supply.
From the books: Atkins, Gesteland & Cech (eds.), RNA Worlds, p. 101.
The wider question for this part of the cell: origins for building carbon into molecules.
Sources
- KEGG map aae00520 (enzymes of this organism highlighted)
Other pathways in this group: Reductive TCA machinery · Sugar-phosphate supply · Pyruvate and acetyl-CoA · Lipid A and outer envelope · Ribose and PRPP supply · Glycolysis / Gluconeogenesis · Pentose phosphate pathway · Not yet placed in a pathway