CATH Classification
| Level | CATH Code | Description |
|---|---|---|
|
3 | Alpha Beta |
|
3.40 | 3-Layer(aba) Sandwich |
|
3.40.1010 | Cobalt-precorrin-4 Transmethylase; domain 1 |
|
3.40.1010.10 | Cobalt-precorrin-4 Transmethylase; Domain 1 |
Domain Context
CATH Clusters
| Superfamily | Cobalt-precorrin-4 Transmethylase; Domain 1 |
| Functional Family | Siroheme synthase |
Enzyme Information
| 1.3.1.76 |
Precorrin-2 dehydrogenase.
based on mapping to UniProt P25924
Precorrin-2 + NAD(+) = sirohydrochlorin + NADH.
-!- Catalyzes the second of three steps leading to the formation of siroheme from uroporphyrinogen III. -!- The first step involves the donation of two S-adenosyl-L-methionine- derived methyl groups to carbons 2 and 7 of uroporphyrinogen III to form precorrin-2 (EC 2.1.1.107) and the third step involves the chelation of ferrous iron to sirohydrochlorin to form siroheme (EC 4.99.1.4). -!- In Saccharomyces cerevisiae, the last two steps are carried out by a single bifunctional enzyme, Met8p. -!- In some bacteria, steps 1-3 are catalyzed by a single multifunctional protein called CysG, whereas in Bacillus megaterium, three separate enzymes carry out each of the steps, with SirC being responsible for the above reaction.
|
| 2.1.1.107 |
Uroporphyrinogen-III C-methyltransferase.
based on mapping to UniProt P25924
2 S-adenosyl-L-methionine + uroporphyrinogen III = 2 S-adenosyl-L- homocysteine + precorrin-2.
-!- This enzyme catalyzes two sequential methylation reactions, the first forming precorrin-1 and the second leading to the formation of precorrin-2. -!- It is the first of three steps leading to the formation of siroheme from uroporphyrinogen III. -!- The second step involves an NAD(+)-dependent dehydrogenation to form sirohydrochlorin from precorrin-2 (EC 1.3.1.76) and the third step involves the chelation of Fe(2+) to sirohydrochlorin to form siroheme (EC 4.99.1.4). -!- In Saccharomyces cerevisiae, the last two steps are carried out by a single bifunctional enzyme, Met8p. -!- In some bacteria, steps 1-3 are catalyzed by a single multifunctional protein called CysG, whereas in Bacillus megaterium, three separate enzymes carry out each of the steps, with SirA being responsible for the above reaction. -!- Also involved in the biosynthesis of cobalamin.
|
| 4.99.1.4 |
Sirohydrochlorin ferrochelatase.
based on mapping to UniProt P25924
Siroheme + 2 H(+) = sirohydrochlorin + Fe(2+).
-!- This enzyme catalyzes the third of three steps leading to the formation of siroheme from uroporphyrinogen III. -!- The first step involves the donation of two S-adenosyl-L-methionine- derived methyl groups to carbons 2 and 7 of uroporphyrinogen III to form precorrin-2 (EC 2.1.1.107) and the second step involves an NAD(+)-dependent dehydrogenation to form sirohydrochlorin from precorrin-2 (EC 1.3.1.76). -!- In Saccharomyces cerevisiae, the last two steps are carried out by a single bifunctional enzyme, Met8p. -!- In some bacteria, steps 1-3 are catalyzed by a single multifunctional protein called CysG, whereas in Bacillus megaterium, three separate enzymes carry out each of the steps, with SirB being responsible for the above reaction.
|
UniProtKB Entries (1)
| P25924 |
CYSG_SALTY
Salmonella enterica subsp. enterica serovar Typhimurium str. LT2
Siroheme synthase
|
PDB Structure
| PDB | 1PJT |
| External Links | |
| Method | X-RAY DIFFRACTION |
| Organism | Escherichia |
| Primary Citation |
CysG structure reveals tetrapyrrole-binding features and novel regulation of siroheme biosynthesis.
Nat.Struct.Biol.
|