CATH Classification

Domain Context

CATH Clusters

Superfamily Methyltransferase, Cobalt-precorrin-4 Transmethylase; Domain 2
Functional Family Siroheme synthase

Enzyme Information

2.1.1.107
Uroporphyrinogen-III C-methyltransferase.
based on mapping to UniProt P21631
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.

UniProtKB Entries (1)

P21631
SUMT_SINSX
Sinorhizobium sp.
Uroporphyrinogen-III C-methyltransferase

PDB Structure

PDB 1S4D
External Links
Method X-RAY DIFFRACTION
Organism Escherichia
Primary Citation
Structure/Function Studies on a S-Adenosyl-l-methionine-dependent Uroporphyrinogen III C Methyltransferase (SUMT), a Key Regulatory Enzyme of Tetrapyrrole Biosynthesis
Vevodova, J., Graham, R.M., Raux, E., Schubert, H.L., Roper, D.I., Brindley, A.A., Scott, A.I., Roessner, C.A., Stamford, N.P.J., Stroupe, M.E., Getzoff, E.D., Warren, M.J., Wilson, K.S.
J.Mol.Biol.