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2  structures 1026  species 0  interactions 1248  sequences 22  architectures

Family: ComA (PF02679)

Summary: (2R)-phospho-3-sulfolactate synthase (ComA)

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(2R)-phospho-3-sulfolactate synthase (ComA) Provide feedback

In methanobacteria (2R)-phospho-3-sulfolactate synthase (ComA) catalyses the first step of the biosynthesis of coenzyme M from phosphoenolpyruvate (P-enolpyruvate). This novel enzyme catalyses the stereospecific Michael addition of sulfite to P-enolpyruvate, forming L-2-phospho-3-sulfolactate (PSL). It is suggested that the ComA-catalysed reaction is analogous to those reactions catalysed by beta-elimination enzymes that proceed through an enolate intermediate [1].

Literature references

  1. Graham DE, Xu H, White RH; , J Biol Chem 2002;277:13421-13429.: Identification of coenzyme M biosynthetic phosphosulfolactate synthase: a new family of sulfonate-biosynthesizing enzymes. PUBMED:11830598 EPMC:11830598

External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR003830

Methanogenic archaea produce methane via the anaerobic reduction of acetate or single carbon compounds [ PUBMED:12440773 ]. Coenzyme M (CoM; 2-mercaptoethanesulphonic acid) serves as the terminal methyl carrier for this process. Previously thought to be unique to methanogenic archaea, CoM has also been found in methylotrophic bacteria.

Biosynthesis of CoM begins with the Michael addition of sulphite to phosphoenolpyruvate, forming 2-phospho-3-sulpholactate (PSL). This reaction is catalyzed by members of this family, PSL synthase (ComA) [ PUBMED:11830598 ]. Subsequently, PSL is dephosphorylated by phosphosulpholactate phosphatase (ComB) to form 3-sulpholactate [ PUBMED:11589710 ], which is then converted to 3-sulphopyruvate by L-sulpholactate dehydrogenase (ComC; EC ) [ PUBMED:10850983 ]. Sulphopyruvate decarboxylase (ComDE; EC ) converts 3-sulphopyruvate to sulphoacetaldehyde [ PUBMED:10940029 ]. Reductive thiolation of sulphoacetaldehyde is the final step.

This entry also includes some proteins from plants and fungi, such as HEAT-STRESS-ASSOCIATED 32 from Arabidopsis [ PUBMED:23439916 ].

Domain organisation

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

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We store a range of different sequence alignments for families. As well as the seed alignment from which the family is built, we provide the full alignment, generated by searching the sequence database (reference proteomes) using the family HMM. We also generate alignments using four representative proteomes (RP) sets and the UniProtKB sequence database. More...

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We make a range of alignments for each Pfam-A family. You can see a description of each above. You can view these alignments in various ways but please note that some types of alignment are never generated while others may not be available for all families, most commonly because the alignments are too large to handle.

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

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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...


This page displays the phylogenetic tree for this family's seed alignment. 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 alignment.

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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 View help on the curation process

Seed source: COG1809
Previous IDs: DUF210;
Type: Family
Sequence Ontology: SO:0100021
Author: Mian N , Bateman A
Number in seed: 98
Number in full: 1248
Average length of the domain: 233.30 aa
Average identity of full alignment: 34 %
Average coverage of the sequence by the domain: 77.05 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 57096847 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 25.2 25.2
Trusted cut-off 25.3 25.2
Noise cut-off 24.5 23.8
Model length: 243
Family (HMM) version: 17
Download: download the raw HMM for this family

Species distribution

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Colour assignments

Archea Archea Eukaryota Eukaryota
Bacteria Bacteria Other sequences Other sequences
Viruses Viruses Unclassified Unclassified
Viroids Viroids Unclassified sequence Unclassified sequence


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For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the ComA domain has been found. There are 2 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein sequence.

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AlphaFold Structure Predictions

The list of proteins below match this family and have AlphaFold predicted structures. Click on the protein accession to view the predicted structure.

Protein Predicted structure External Information
A0A0R4J3V8 View 3D Structure Click here
B6THJ5 View 3D Structure Click here
I1KLA4 View 3D Structure Click here
Q57703 View 3D Structure Click here
Q653W2 View 3D Structure Click here
Q8GWL1 View 3D Structure Click here