|Superclasses:||Reactions Classified By Conversion Type → Simple Reactions → Chemical Reactions → Composite Reactions|
|Reactions Classified By Substrate → Small-Molecule Reactions|
EC Number: 126.96.36.199
Enzymes and Genes:
uroporphyrin-III methyltransferase : cobA ( Pseudomonas denitrificans )
uroporphyrinogen-III C-methyltransferase : corA ( Methanobacterium ivanovii )
uroporphyrinogen-III (C7)-methyltransferase [multifunctional] : cysG ( Salmonella enterica enterica serovar Typhimurium )
uroporphyrinogen-III C-methyltransferase : MET1 ( Saccharomyces cerevisiae )
uroporphyrin III C-methyltransferase [multifunctional] : cysG ( Escherichia coli K-12 substr. MG1655 )
The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.
Most BioCyc compounds have been protonated to a reference pH value of 7.3, and some reactions have been computationally balanced for hydrogen by adding free protons. Please see the PGDB Concepts Guide for more information.
Mass balance status: Balanced.
Enzyme Commission Primary Name: uroporphyrinogen-III C-methyltransferase
Enzyme Commission Synonyms: uroporphyrinogen methyltransferase, uroporphyrinogen-III methyltransferase, adenosylmethionine-uroporphyrinogen III methyltransferase, S-adenosyl-L-methionine-dependent uroporphyrinogen III methylase, uroporphyrinogen-III methylase, SirA, CysG, CobA [ambiguous - see EC 188.8.131.52] SUMT, uroporphyrin-III C-methyltransferase (incorrect), S-adenosyl-L-methionine:uroporphyrin-III C-methyltransferase (incorrect)
Standard Gibbs Free Energy (ΔrG'° in kcal/mol): -12.957092 [Latendresse13]
Enzyme Commission Summary:
This reaction is a summary of two individual reactions catalyzed by the enzyme, which are listed above.
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 184.108.40.206) and the third step involves the chelation of Fe(2+) to sirohydrochlorin to form siroheme (EC 220.127.116.11). 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.
Unification Links: Rhea:32459
Schubert02: Schubert HL, Raux E, Brindley AA, Leech HK, Wilson KS, Hill CP, Warren MJ (2002). "The structure of Saccharomyces cerevisiae Met8p, a bifunctional dehydrogenase and ferrochelatase." EMBO J 21(9);2068-75. PMID: 11980703
Warren90: Warren MJ, Roessner CA, Santander PJ, Scott AI (1990). "The Escherichia coli cysG gene encodes S-adenosylmethionine-dependent uroporphyrinogen III methylase." Biochem J 265(3);725-9. PMID: 2407234
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