H
IPR036453

Glutamyl tRNA-reductase dimerization domain superfamily

InterPro entry
Short nameGluRdtase_dimer_dom_sf
Overlapping entries
 

Description

Tetrapyrroles are large macrocyclic compounds derived from a common biosynthetic pathway
[2]
. The end-product, uroporphyrinogen III, is used to synthesise a number of important molecules, including vitamin B12, haem, sirohaem, chlorophyll, coenzyme F430 and phytochromobilin
[3]
.


 * The first stage in tetrapyrrole synthesis is the synthesis of 5-aminoaevulinic acid ALA via two possible routes: (1) condensation of succinyl CoA and glycine (C4 pathway) using ALA synthase (
2.3.1.37
), or (2) decarboxylation of glutamate (C5 pathway) via three different enzymes, glutamyl-tRNA synthetase (
6.1.1.17
) to charge a tRNA with glutamate, glutamyl-tRNA reductase (
1.2.1.70
) to reduce glutamyl-tRNA to glutamate-1-semialdehyde (GSA), and GSA aminotransferase (
5.4.3.8
) to catalyse a transamination reaction to produce ALA.


 * The second stage is to convert ALA to uroporphyrinogen III, the first macrocyclic tetrapyrrolic structure in the pathway. This is achieved by the action of three enzymes in one common pathway: porphobilinogen (PBG) synthase (or ALA dehydratase,
4.2.1.24
) to condense two ALA molecules to generate porphobilinogen; hydroxymethylbilane synthase (or PBG deaminase,
2.5.1.61
) to polymerise four PBG molecules into preuroporphyrinogen (tetrapyrrole structure); and uroporphyrinogen III synthase (
4.2.1.75
) to link two pyrrole units together (rings A and D) to yield uroporphyrinogen III.


 * Uroporphyrinogen III is the first branch point of the pathway. To synthesise cobalamin (vitamin B12), sirohaem, and coenzyme F430, uroporphyrinogen III needs to be converted into precorrin-2 by the action of uroporphyrinogen III methyltransferase (
2.1.1.107
). To synthesise haem and chlorophyll, uroporphyrinogen III needs to be decarboxylated into coproporphyrinogen III by the action of uroporphyrinogen III decarboxylase (
4.1.1.37
)
[4]
.


This entry represents the helical dimerisation domain superfamily of glutamyl-tRNA reductase (
1.2.1.70
)
[1]
. This enzyme reduces glutamyl-tRNA to glutamate-1-semialdehyde during the first stage of tetrapyrrole biosynthesis by the C5 pathway
[4, 5]
. The enzyme requires NADPH as a cofactor.

References

1.V-shaped structure of glutamyl-tRNA reductase, the first enzyme of tRNA-dependent tetrapyrrole biosynthesis. Moser J, Schubert WD, Beier V, Bringemeier I, Jahn D, Heinz DW. EMBO J. 20, 6583-90, (2001). View articlePMID: 11726494

2.Evolutionary relationship between initial enzymes of tetrapyrrole biosynthesis. Schulze JO, Schubert WD, Moser J, Jahn D, Heinz DW. J. Mol. Biol. 358, 1212-20, (2006). View articlePMID: 16564539

3.Tetrapyrrole biosynthesis in higher plants. Tanaka R, Tanaka A. 58, 321-46, (2007). View articlePMID: 17227226

4.Biosynthesis of cobalamin (vitamin B12): a bacterial conundrum. Raux E, Schubert HL, Warren MJ. Cell. Mol. Life Sci. 57, 1880-93, (2000). View articlePMID: 11215515

5.Glutamyl-transfer RNA: a precursor of heme and chlorophyll biosynthesis. Jahn D, Verkamp E, Soll D. Trends Biochem. Sci. 17, 215-8, (1992). View articlePMID: 1502723

GO terms

Cross References

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