Pathway · 2 proteins
Nicotinate and nicotinamide metabolism
Proteins of this group that KEGG places on its “Nicotinate and nicotinamide metabolism” map for Aquifex aeolicus.
How it works
This map covers the making and recycling of NAD. The proteins here start the route from aspartate (L-aspartate oxidase), finish NAD using glutamine, add a phosphate to make NADP, and recycle nicotinamide released when NAD is used up, for example by the protein deacylase on this page.
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 |
|---|---|---|---|---|---|
| CinA C-terminal domain-containing protein | — | — | — | 229 | Unspecified |
| NAD-dependent protein deacylase | 2.3.1.286 | N(6)-acetyl-L-lysyl-[protein] + NAD(+) + H2O = 2''-O-acetyl-ADP-D-ribose + nicotinamide + L-lysyl-[protein] | Zn(2+) | 239 | Unspecified |
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 |
|---|---|---|---|---|---|
| 5'-nucleotidase SurEHome: Purine metabolism | 3.1.3.5 | a ribonucleoside 5'-phosphate + H2O = a ribonucleoside + phosphate | — | 251 | Step named |
| Probable nicotinate-nucleotide adenylyltransferaseHome: NAD and flavins | 2.7.7.18 | nicotinate beta-D-ribonucleotide + ATP + H(+) = deamido-NAD(+) + diphosphate | — | 168 | Step named |
| Nicotinate phosphoribosyltransferaseHome: NAD and flavins | 6.3.4.21 | 5-phospho-alpha-D-ribose 1-diphosphate + nicotinate + ATP + H2O = nicotinate beta-D-ribonucleotide + ADP + phosphate + diphosphate | — | 426 | Step named |
| Quinolinate synthaseHome: NAD and flavins | 2.5.1.72 | iminosuccinate + dihydroxyacetone phosphate = quinolinate + phosphate + 2 H2O + H(+) | [4Fe-4S] cluster | 322 | Step named |
| L-aspartate oxidaseHome: Nicotinate and nicotinamide metabolism | 1.4.3.16 | L-aspartate + O2 = iminosuccinate + H2O2 | — | 510 | Step named |
| Probable nicotinate-nucleotide pyrophosphorylase [carboxylating]Home: NAD and flavins | 2.4.2.19 | nicotinate beta-D-ribonucleotide + CO2 + diphosphate = quinolinate + 5-phospho-alpha-D-ribose 1-diphosphate + 2 H(+) | — | 274 | Step named |
| NAD kinaseHome: Nicotinate and nicotinamide metabolism | 2.7.1.23 | NAD(+) + ATP = ADP + NADP(+) + H(+) | — | 274 | Step named |
| Glutamine-dependent NAD(+) synthetaseHome: Nicotinate and nicotinamide metabolism | 6.3.5.1 | deamido-NAD(+) + L-glutamine + ATP + H2O = L-glutamate + AMP + diphosphate + NAD(+) + H(+) | — | 567 | Step named |
| nicotinamidaseHome: Nicotinate and nicotinamide metabolism | 3.5.1.19 | — | — | 198 | Step named |
| Nucleoside triphosphate pyrophosphohydrolaseHome: Purine metabolism | 3.6.1.8 | ATP + H2O = AMP + diphosphate + H(+) | — | 257 | Unspecified |
Origins
Could the nicotinamide ring of NAD have formed before cells?
Nicotinamide can be reached from plausibly prebiotic chemicals by several routes, from ethylene and ammonia (Friedmann et al. 1971) or from aspartate and dihydroxyacetone phosphate (Cleaves and Miller 2001). On this basis Yarus considers NAD-like cofactors early participants in biochemistry.
A ring is not yet a working cofactor: NAD needs ribose, phosphate and an adenine nucleotide joined in the right way, and four proteins in this group build and recycle it.
From the books: Atkins, Gesteland & Cech (eds.), RNA Worlds, p. 48; Ribas de Pouplana (ed.), The Genetic Code and the Origin of Life, p. 67.
The wider question for this part of the cell: origins for conserved, but we cannot say what they do.
Sources
- KEGG map aae00760 (enzymes of this organism highlighted)
Other pathways in this group: tRNA charging · Nutrient and metabolic state · Biosynthesis of various nucleotide sugars · Purine metabolism · Bacterial secretion system · Glyoxylate and dicarboxylate metabolism · Starch and sucrose metabolism · Homologous recombination · Fructose and mannose metabolism · Streptomycin biosynthesis · Other carbon fixation pathways · Not yet placed in a pathway