Summary

Precorrin-6x reductase CbiJ/CobK

This family consists of Precorrin-6x reductase EC:1.3.1.54. This enzyme catalyses the reaction: precorrin-6Y + NADP(+) <=> precorrin-6X + NADPH. CbiJ and CobK both catalyse the reduction of macocycle in the colbalmin biosynthesis pathway [1,2].

Literature references

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
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

InterPro entry IPR003723

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 CobK and CbiJ precorrin-6x reductase (). In the aerobic pathway, CobK catalyses the reduction of the macrocycle of precorrin-6X to produce precorrin-6Y; while in the anaerobic pathway CbiJ catalyses the reduction of the macrocycle of cobalt-precorrin-6X into cobalt-precorrin-6Y PUBMED:16243778, PUBMED:10559155.

Gene Ontology

Molecular function	precorrin-6A reductase activity (GO:0016994)
Biological process	cobalamin biosynthetic process (GO:0009236)
Biological process	oxidation reduction (GO:0055114)

External database links

PANDIT:	PF02571
SYSTERS:	CbiJ

Domain organisation

Below is a listing of the unique domain organisations or architectures in which this domain is found. More...

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Alignments

There are various ways to view or download the sequence alignments that we store. You can use a sequence viewer to look at either the seed or full alignment for the family, or you can look at a plain text version of the sequence in a variety of different formats. More...

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Alignment:	Seed (90) Full (505) NCBI (641) Metagenomics (325)
Viewer:

Formatting options

Alignment:	Seed (90) Full (505)
Format:
Order:	Tree Alphabetical
Sequence:	Inserts lower case All upper case
Gaps:
Download/view:	Download View

Download options

Very large alignments can often cause problems for the formatting tool above. If you find that downloading or viewing a large alignment is problematic, you can also download a gzip-compressed, Stockholm-format file containing the seed or full alignment for this family.

You can also download a FASTA format file containing the full-length sequences for all sequences in the full alignment.

The main seed and full alignments are generated using sequences from the UniProt sequence database. However, we also generate alignments using sequences from the NCBI sequence database and the "metaseq" metagenomics dataset.

You can view alignments from these two additional datasets using the form above, or you can download alignments of NCBI or metagenomics sequences, as gzip-compressed files.

Pfam alignments:	Seed (90) Full (505) NCBI (641) Metagenomics (325)
Full length sequences	Full-sequences (505)

External links

MyHits provides a collection of tools to handle multiple sequence alignments. For example, one can refine a seed alignment (sequence addition or removal, re-alignment or manual edition) and then search databases for remote homologs using HMMER2.

HMM logo

HMM logos is one way of visualising profile HMMs. Logos provide a quick overview of the properties of an HMM in a graphical form. You can see a more detailed description of HMM logos and find out how you can interpret them here. More...

Trees

This page displays the phylogenetic tree for this family. We use FastTree to calculate neighbour join trees with a local bootstrap based on 100 resamples (shown next to the tree nodes). FastTree calculates approximately-maximum-likelihood phylogenetic trees from our seed or full alignments.

Note: You can also download the data files for the seed, full, NCBI or metagenomics trees.

Curation and family details

This section shows the detailed information about the Pfam family. You can see the definitions of many of the terms in this section in the glossary and a fuller explanation of the scoring system that we use in the scores section of the help pages.

Curation

Seed source:

COGs

Previous IDs:

none

Type:

Family

Author:

Bashton M, Bateman A

Number in seed:

90

Number in full:

505

Average length of the domain:

242.50 aa

Average identity of full alignment:

30 %

Average coverage of the sequence by the domain:

85.98 %

HMM information

HMM build commands:

build method: hmmbuild -o /dev/null HMM SEED

search method: hmmsearch -Z 9421015 -E 1000 HMM pfamseq

Model details:

Parameter	Sequence	Domain
Gathering cut-off	24.9	24.9
Trusted cut-off	25.4	51.0
Noise cut-off	20.9	24.8

Model length:

250

Family (HMM) version:

7

Download:

download the raw HMM for this family

Species distribution

Tree controls

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The tree shows the occurrence of this domain across different species. More...

Species trees

We show the species tree in one of two ways. For smaller trees we try to show an interactive representation, which allows you to select specific nodes in the tree and view them as an alignment or as a set of Pfam domain graphics.

Unfortunately we have found that there are problems viewing the interactive tree when the it becomes larger than a certain limit. Furthermore, we have found that Internet Explorer can become unresponsive when viewing some trees, regardless of their size. We therefore show a text representation of the species tree when the size is above a certain limit or if you are using Internet Explorer to view the site.

If you are using IE you can still load the interactive tree by clicking the "Generate interactive tree" button, but please be aware of the potential problems that the interactive species tree can cause.

Interactive tree

For all of the domain matches in a full alignment, we count the number that are found on all sequences in the alignment. This total is shown in the purple box.

We also count the number of unique sequences on which each domain is found, which is shown in green. Note that a domain may appear multiple times on the same sequence, leading to the difference between these two numbers.

Finally, we group sequences from the same organism according to the NCBI code that is assigned by UniProt, allowing us to count the number of distinct sequences on which the domain is found. This value is shown in the pink boxes.

We use the NCBI species tree to group organisms according to their taxonomy and this forms the structure of the displayed tree. Note that in some cases the trees are too large (have too many nodes) to allow us to build an interactive tree, but in most cases you can still view the tree in a plain text, non-interactive representation. Those species which are represented in the seed alignment for this domain are highlighted.

You can use the tree controls to manipulate how the interactive tree is displayed:

show/hide the summary boxes
highlight species that are represented in the seed alignment
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Family: CbiJ (PF02571)

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