Summary: Precorrin-8X methylmutase
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Precorrin-8X methylmutase Provide feedback
This is a family Precorrin-8X methylmutases also known as Precorrin isomerase, CbiC/CobH, EC:126.96.36.199. This enzyme catalyses the reaction: Precorrin-8X <=> hydrogenobyrinate. This enzyme is part of the Cobalamin (vitamin B12) biosynthetic pathway and catalyses a methyl rearrangement [1,2].
Raux E, Lanois A, Warren MJ, Rambach A, Thermes C; , Biochem J 1998;335:159-166.: Cobalamin (vitamin B12) biosynthesis: identification and characterization of a Bacillus megaterium cobI operon. PUBMED:9742225 EPMC:9742225
Roth JR, Lawrence JG, Rubenfield M, Kieffer-Higgins S, Church GM; , J Bacteriol 1993;175:3303-3316.: Characterization of the cobalamin (vitamin B12) biosynthetic genes of Salmonella typhimurium. PUBMED:8501034 EPMC:8501034
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This tab holds annotation information from the InterPro database.
InterPro entry IPR003722
Cobalamin (vitamin B12) is a structurally complex cofactor, consisting of a modified tetrapyrrole with a centrally chelated cobalt. Cobalamin is usually found in one of two biologically active forms: methylcobalamin and adocobalamin. Most prokaryotes, as well as animals, have cobalamin-dependent enzymes, whereas plants and fungi do not appear to use it. In bacteria and archaea, these include methionine synthase, ribonucleotide reductase, glutamate and methylmalonyl-CoA mutases, ethanolamine ammonia lyase, and diol dehydratase [PUBMED:12869542]. In mammals, cobalamin is obtained through the diet, and is required for methionine synthase and methylmalonyl-CoA mutase [PUBMED:17163662].
There are at least two distinct cobalamin biosynthetic pathways in bacteria [PUBMED:11153269]:
- Aerobic pathway that requires oxygen and in which cobalt is inserted late in the pathway [PUBMED:16042605]; found in Pseudomonas denitrificans and Rhodobacter capsulatus.
- Anaerobic pathway in which cobalt insertion is the first committed step towards cobalamin synthesis [PUBMED:12055304]; found in Salmonella typhimurium, Bacillus megaterium, and Propionibacterium freudenreichii subsp. shermanii.
Either pathway can be divided into two parts: (1) corrin ring synthesis (differs in aerobic and anaerobic pathways) and (2) adenosylation of corrin ring, attachment of aminopropanol arm, and assembly of the nucleotide loop (common to both pathways) [PUBMED:11215515]. There are about 30 enzymes involved in either pathway, where those involved in the aerobic pathway are prefixed Cob and those of the anaerobic pathway Cbi. Several of these enzymes are pathway-specific: CbiD, CbiG, and CbiK are specific to the anaerobic route of S. typhimurium, whereas CobE, CobF, CobG, CobN, CobS, CobT, and CobW are unique to the aerobic pathway of P. denitrificans.
This entry represents CbiC and CobH precorrin-8X methylmutase (also known as precorrin isomerase, EC), both as stand-alone enzymes and when CobJ forms part of a bifunctional enzyme. CobH and CbiC from the aerobic and anaerobic pathways, respectively, catalyse a methyl rearrangement in precorrin-8 that moves the methyl group from C-11 to C-12 to produce hydrogenobyrinic acid [PUBMED:11470433]. Hydrogenobyrinic acid now contains all the major framework alterations associated with corrin synthesis [PUBMED:11215515].
CobH and CbiC can sometimes be fused to other enzymes in the cobalamin pathway to make bifunctional enzymes: e.g., with CobJ/CibH (precorrin-3B C17-methylase/precorrin isomerase, INTERPRO) and with CbiX (precorrin isomerase, INTERPRO).
The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.
|Molecular function||precorrin-8X methylmutase activity (GO:0016993)|
|Biological process||cobalamin biosynthetic process (GO:0009236)|
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Curation and family details
|Author:||Bashton M, Bateman A|
|Number in seed:||155|
|Number in full:||1640|
|Average length of the domain:||196.50 aa|
|Average identity of full alignment:||41 %|
|Average coverage of the sequence by the domain:||85.28 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||10|
|Download:||download the raw HMM for this family|
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