Uroporphyrinogen-III C-methyltransferase explained

Uroporphyrinogen-III C-methyltransferase
Ec Number:	2.1.1.107
Cas Number:	125752-76-3

Uroporphyrinogen-III C-methyltransferase, uroporphyrinogen methyltransferase, uroporphyrinogen-III methyltransferase, adenosylmethionine-uroporphyrinogen III methyltransferase, S-adenosyl-L-methionine-dependent uroporphyrinogen III methylase, uroporphyrinogen-III methylase, SirA, CysG, CobA, uroporphyrin-III C-methyltransferase, S-adenosyl-L-methionine:uroporphyrin-III C-methyltransferase) is an enzyme with systematic name S-adenosyl-L-methionine:uroporphyrinogen-III C-methyltransferase.^{[1] [2] [3]} This enzyme catalyses the following chemical reaction

2 S-adenosyl-L-methionine + uroporphyrinogen III

\rightleftharpoons 2 S-adenosyl-L-homocysteine + precorrin-2 (overall reaction)

(1a) S-adenosyl-L-methionine + uroporphyrinogen III

\rightleftharpoons S-adenosyl-L-homocysteine + precorrin-1

(1b) S-adenosyl-L-methionine + precorrin-1

\rightleftharpoons S-adenosyl-L-homocysteine + precorrin-2Uroporphyrinogen-III C-methyltransferase catalyses two methylation reactions. The first reaction converts uroporphyrinogen III into precorrin-1. The second converts precorrin-1 into precorrin-2. These reactions are part of the biosynthetic pathway to cobalamin (vitamin B₁₂) in both anaerobic and aerobic bacteria.

See also

• Cobalamin biosynthesis

Notes and References

1. Uroporphyrinogen-III methylase catalyzes the enzymatic-synthesis of sirohydrochlorin-II and sirohydrochlorin-IV by a clockwise mechanism . Warren MJ, Gonzalez MD, Williams HJ, Stolowich NJ, Scott AI . J. Am. Chem. Soc. . 1990 . 112 . 5343–5345 . 10.1021/ja00169a048.
2. Warren MJ, Roessner CA, Santander PJ, Scott AI . The Escherichia coli cysG gene encodes S-adenosylmethionine-dependent uroporphyrinogen III methylase . The Biochemical Journal . 265 . 3 . 725–9 . February 1990 . 2407234 . 1133693 . 10.1042/bj2650725 .
3. Schubert HL, Raux E, Brindley AA, Leech HK, Wilson KS, Hill CP, Warren MJ . The structure of Saccharomyces cerevisiae Met8p, a bifunctional dehydrogenase and ferrochelatase . The EMBO Journal . 21 . 9 . 2068–75 . May 2002 . 11980703 . 125995 . 10.1093/emboj/21.9.2068 .