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22  structures 246  species 1  interaction 359  sequences 6  architectures

Family: Tautomerase_3 (PF14832)

Summary: Putative oxalocrotonate tautomerase enzyme

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This is the Wikipedia entry entitled "4-Oxalocrotonate tautomerase". More...

4-Oxalocrotonate tautomerase Edit Wikipedia article

4-oxalocrotonate tautomerase
Symbol Taut
Pfam PF01361
InterPro IPR004370
CDD cd00491

4-Oxalocrotonate tautomerase (EC 5.3.2.-4-OT) is an enzyme that converts 2-hydroxymuconate to the αβ-unsaturated ketone, 2-oxo-3-hexenedioate.[1] This enzyme forms part of a bacterial metabolic pathway that oxidatively catabolizes toluene, o-xylene, 3-ethyltoluene, and 1,2,4-trimethylbenzene into intermediates of the citric acid cycle. With a monomer size of just 62 amino acid residues, the 4-Oxalocrotonate tautomerase is one of the smallest enzyme subunits known.[2] However, in solution, the enzyme forms a hexamer of six identical subunits, so the active site may be formed by amino acid residues from several subunits.[3] This enzyme is also unusual in that it uses a proline residue at the amino terminus as an active site residue.


  1. ^ Chen LH, Kenyon GL, Curtin F, Harayama S, Bembenek ME, Hajipour G, Whitman CP (1992). "4-Oxalocrotonate tautomerase, an enzyme composed of 62 amino acid residues per monomer". J. Biol. Chem. 267 (25): 17716–21. PMID 1339435. 
  2. ^ Whitman CP (2002). "The 4-oxalocrotonate tautomerase family of enzymes: how nature makes new enzymes using a beta-alpha-beta structural motif". Arch. Biochem. Biophys. 402 (1): 1–13. doi:10.1016/S0003-9861(02)00052-8. PMID 12051677. 
  3. ^ Subramanya HS, Roper DI, Dauter Z, Dodson EJ, Davies GJ, Wilson KS, Wigley DB. Enzymatic ketonization of 2-hydroxymuconate: specificity and mechanism investigated by the crystal structures of two isomerases. (1996) Biochemistry. 35(3):792-802. PMID 8547259

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Putative oxalocrotonate tautomerase enzyme Provide feedback

4-oxalocrotonate tautomerase enzyme is involved in the anthranilate synthase pathway.1

Internal database links

External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR028116

This domain represents a putative 4-oxalocrotonate tautomerase.

4-oxalocrotonate tautomerase (4-OT) is a member of the tautomerase superfamily, and it is an essential enzyme in the degradative metabolism pathway occurring in the Krebs cycle [PUBMED:22417185]. The functional unit is apparently a pentamer of identical subunits, each consisting of only 62 amino acid residues [PUBMED:1339435].

Domain organisation

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

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Pfam Clan

This family is a member of clan MIF (CL0082), which has the following description:

This clan groups 5-(carboxymethyl)-2-hydroxymuconate isomerase (CHMI) and 4-oxalocrotonate tautomerase (4-OT) with macrophage inhibitory factor (MIF). Interestingly they all share an amino-terminal proline. Members of this clan for homotrimers [1].

The clan contains the following 6 members:

CHMI DUF1904 MIF Tautomerase Tautomerase_2 Tautomerase_3


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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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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.

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Seed source: CATH:3c6v_A_00
Previous IDs: none
Type: Domain
Author: Coggill P
Number in seed: 21
Number in full: 359
Average length of the domain: 133.10 aa
Average identity of full alignment: 30 %
Average coverage of the sequence by the domain: 82.47 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 80369284 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 25.7 25.7
Trusted cut-off 25.8 25.7
Noise cut-off 25.4 25.4
Model length: 137
Family (HMM) version: 2
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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There is 1 interaction for this family. More...



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 Tautomerase_3 domain has been found. There are 22 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 seqence.

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