{PDOC00656}
{PS00839; SUMT_1}
{PS00840; SUMT_2}
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* Uroporphyrin-III C-methyltransferase signatures *
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Uroporphyrin-III C-methyltransferase (EC 2.1.1.107) (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]).

-Consensus pattern: [LIVM]-[GS]-[STAL]-G-P-G-x(3)-[LIVMFY]-[LIVM]-T-[LIVM]-
                    [KRHQG]-[AG]
-Sequences known to belong to this class detected by the pattern: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.

-Consensus pattern: [VW]-x(2)-[LI]-x(2)-[GA]-[DT]-x(3)-[FYW]-[GS]-x(8)-
                    [LIVFA]-x(5,6)-[LIVMFYWPAC]-x-[LIVMY]-x-[PN]-G
-Sequences known to belong to this class detected by the pattern: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.

-Note: Yeast  diphthine  synthase  (EC  2.1.1.98)  (gene DPH5) seems to be [5]
 evolutionary related to SUMT, but is not detected by the above patterns.

-Last update: December 2004 / Pattern and text revised.

[ 1] Blanche F., Robin C., Couder M., Faucher D., Cauchois L., Cameron B.,
     Crouzet J.
     "Purification, characterization, and molecular cloning of
     S-adenosyl-L-methionine: uroporphyrinogen III methyltransferase from
     Methanobacterium ivanovii."
     J. Bacteriol. 173:4637-4645(1991).
     PubMed=1856165
[ 2] Robin C., Blanche F., Cauchois L., Cameron B., Couder M., Crouzet J.
     "Primary structure, expression in Escherichia coli, and properties of
     S-adenosyl-L-methionine:uroporphyrinogen III methyltransferase from
     Bacillus megaterium."
     J. Bacteriol. 173:4893-4896(1991).
     PubMed=1906874
[ 3] Crouzet J., Cameron B., Cauchois L., Rigault S., Rouyez M.-C.,
     Blanche F., Thibaut D., Debussche L.
     "Genetic and sequence analysis of an 8.7-kilobase Pseudomonas
     denitrificans fragment carrying eight genes involved in transformation
     of precorrin-2 to cobyrinic acid."
     J. Bacteriol. 172:5980-5990(1990).
     PubMed=2211521
[ 4] Roth J.R., Lawrence J.G., Rubenfield M., Kieffer-Higgins S., Church G.M.
     "Characterization of the cobalamin (vitamin B12) biosynthetic genes of
     Salmonella typhimurium."
     J. Bacteriol. 175:3303-3316(1993).
     PubMed=8501034
[ 5] Mattheakis L.C., Shen W.H., Collier R.J.
     "DPH5, a methyltransferase gene required for diphthamide biosynthesis
     in Saccharomyces cerevisiae."
     Mol. Cell. Biol. 12:4026-4037(1992).
     PubMed=1508200

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