|PROSITE documentation PDOC00656 [for PROSITE entry PS00840]|
Uroporphyrin-III C-methyltransferase (EC 18.104.22.168) (SUMT) [1,2] catalyzes the transfer of two methyl groups from S-adenosyl-L-methionine to the C-2 and C-7 atoms of uroporphyrinogen III to yield precorrin-2 via the intermediate formation of precorrin-1. SUMT is the first enzyme specific to the cobalamin pathway and precorrin-2 is a common intermediate in the biosynthesis of corrinoids such as vitamin B12, siroheme and coenzyme F430.
The sequences of SUMT from a variety of eubacterial and archaebacterial species are currently available. In species such as Bacillus megaterium (gene cobA), Pseudomonas denitrificans (cobA) or Methanobacterium ivanovii (gene corA) SUMT is a protein of about 25 to 30 Kd. In Escherichia coli and related bacteria, the cysG protein, which is involved in the biosynthesis of siroheme, is a multifunctional protein composed of a N-terminal domain, probably involved in transforming precorrin-2 into siroheme, and a C-terminal domain which has SUMT activity.
The sequence of SUMT is related to that of a number of P. denitrificans and Salmonella typhimurium enzymes involved in the biosynthesis of cobalamin which also seem to be SAM-dependent methyltransferases [3,4]. The similarity is especially strong with two of these enzymes: cobI/cbiL which encodes S-adenosyl-L-methionine--precorrin-2 methyltransferase and cobM/cbiF whose exact function is not known.
We developed two signature patterns for these enzymes. The first corresponds to a well conserved region in the N-terminal extremity (called region 1 in [1,3]) and the second to a less conserved region located in the central part of these proteins (this pattern spans what are called regions 2 and 3 in [1,3]).Note:
December 2004 / Pattern and text revised.
PROSITE methods (with tools and information) covered by this documentation:
|1||Authors||Blanche F., Robin C., Couder M., Faucher D., Cauchois L., Cameron B., Crouzet J.|
|Title||Purification, characterization, and molecular cloning of S-adenosyl-L-methionine: uroporphyrinogen III methyltransferase from Methanobacterium ivanovii.|
|Source||J. Bacteriol. 173:4637-4645(1991).|
|2||Authors||Robin C., Blanche F., Cauchois L., Cameron B., Couder M., Crouzet J.|
|Title||Primary structure, expression in Escherichia coli, and properties of S-adenosyl-L-methionine:uroporphyrinogen III methyltransferase from Bacillus megaterium.|
|Source||J. Bacteriol. 173:4893-4896(1991).|
|3||Authors||Crouzet J., Cameron B., Cauchois L., Rigault S., Rouyez M.-C., Blanche F., Thibaut D., Debussche L.|
|Title||Genetic and sequence analysis of an 8.7-kilobase Pseudomonas denitrificans fragment carrying eight genes involved in transformation of precorrin-2 to cobyrinic acid.|
|Source||J. Bacteriol. 172:5980-5990(1990).|
|4||Authors||Roth J.R., Lawrence J.G., Rubenfield M., Kieffer-Higgins S., Church G.M.|
|Title||Characterization of the cobalamin (vitamin B12) biosynthetic genes of Salmonella typhimurium.|
|Source||J. Bacteriol. 175:3303-3316(1993).|
|5||Authors||Mattheakis L.C., Shen W.H., Collier R.J.|
|Title||DPH5, a methyltransferase gene required for diphthamide biosynthesis in Saccharomyces cerevisiae.|
|Source||Mol. Cell. Biol. 12:4026-4037(1992).|