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29  structures 82  species 0  interactions 164  sequences 6  architectures

Family: Enterotoxin_a (PF01375)

Summary: Heat-labile enterotoxin alpha chain

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This is the Wikipedia entry entitled "Heat-labile enterotoxin family". More...

Heat-labile enterotoxin family Edit Wikipedia article

Heat-labile enterotoxin alpha chain
PDB 1s5e EBI.jpg
cholera holotoxin, crystal form 1
Identifiers
Symbol Enterotoxin_a
Pfam PF01375
Pfam clan CL0084
InterPro IPR001144
SCOP 1lts
SUPERFAMILY 1lts
Heat-labile enterotoxin beta chain
PDB 1eei EBI.jpg
cholera toxin b-pentamer complexed with metanitrophenyl-alpha-d-galactose
Identifiers
Symbol Enterotoxin_b
Pfam PF01376
InterPro IPR001835
SCOP 1lts
SUPERFAMILY 1lts
Type II heat-labile enterotoxin , B subunit (LT-IIB)
PDB 1qb5 EBI.jpg
escherichia coli heat labile enterotoxin type iib b-pentamer
Identifiers
Symbol LT-IIB
Pfam PF06453
InterPro IPR010503
SCOP 1tii
SUPERFAMILY 1tii

In molecular biology, the heat-labile enterotoxin family includes Escherichia coli heat-labile toxin and cholera toxin secreted by Vibrio cholerae. These toxins consist of an AB5 multimer structure, in which a pentamer of B chains has a membrane-binding function and an A chain is needed for enzymatic activity.[1] The B subunits are arranged as a doughnut-shaped pentamer, each subunit participating in ~30 hydrogen bonds and 6 salt bridges with its two neighbours.[1]

The A subunit has a less well-defined secondary structure. It predominantly interacts with the pentamer via the C-terminal A2 fragment, which runs through the charged central pore of the B subunits. A putative catalytic residue in the A1 fragment (Glu112) lies close to a hydrophobic region, which packs two loops together. It is thought that this region might be important for catalysis and membrane translocation.[1]

The structural arrangement of type I and type II heat-labile enterotoxins are very similar, although they are antigenically distinct.[2]

References[edit]

  1. ^ a b c Sixma TK, Kalk KH, van Zanten BA, Dauter Z, Kingma J, Witholt B, Hol WG (April 1993). "Refined structure of Escherichia coli heat-labile enterotoxin, a close relative of cholera toxin". J. Mol. Biol. 230 (3): 890–918. doi:10.1006/jmbi.1993.1209. PMID 8478941. 
  2. ^ van den Akker F, Sarfaty S, Twiddy EM, Connell TD, Holmes RK, Hol WG (June 1996). "Crystal structure of a new heat-labile enterotoxin, LT-IIb". Structure 4 (6): 665–78. PMID 8805549. 

This article incorporates text from the public domain Pfam and InterPro IPR001835

This article incorporates text from the public domain Pfam and InterPro IPR001144

This article incorporates text from the public domain Pfam and InterPro IPR010503

This page is based on a Wikipedia article. The text is available under the Creative Commons Attribution/Share-Alike License.

This tab holds the annotation information that is stored in the Pfam database. As we move to using Wikipedia as our main source of annotation, the contents of this tab will be gradually replaced by the Wikipedia tab.

Heat-labile enterotoxin alpha chain Provide feedback

No Pfam abstract.

Literature references

  1. Sixma TK, Kalk KH, van Zanten BA, Dauter Z, Kingma J, Witholt B, Hol WG; , J Mol Biol 1993;230:890-918.: Refined structure of Escherichia coli heat-labile enterotoxin, a close relative of cholera toxin. PUBMED:8478941 EPMC:8478941


External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR001144

Escherichia coli heat-labile enterotoxin is a bacterial protein toxin with an AB5 multimer structure, in which the B pentamer (INTERPRO) has a membrane-binding function and the A chain is needed for enzymatic activity [PUBMED:8478941]. The B subunits are arranged as a donut-shaped pentamer, each subunit participating in ~30 hydrogen bonds and 6 salt bridges with its two neighbours [PUBMED:8478941].

The A subunit has a less well-defined secondary structure. It predominantly interacts with the pentamer via the C-terminal A2 fragment, which runs through the charged central pore of the B subunits. A putative catalytic residue in the A1 fragment (Glu112) lies close to a hydrophobic region, which packs two loops together. It is thought that this region might be important for catalysis and membrane translocation [PUBMED:8478941].

Gene Ontology

The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.

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 ADP-ribosyl (CL0084), which has the following description:

The members of this clan all represent ADP-ribosylating catalytic domains. The structurally conserved regions are located at the NAD binding region [1]. According to SCOP, the ADP-ribosylation domain is thought to have an "unusual fold".

The clan contains the following 6 members:

ADPrib_exo_Tox ART Diphtheria_C Enterotoxin_a PARP Pertussis_S1

Alignments

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 using the family HMM. We also generate alignments using four representative proteomes (RP) sets, the NCBI sequence database, and our metagenomics 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.

  Seed
(6)
Full
(164)
Representative proteomes NCBI
(164)
Meta
(0)
RP15
(3)
RP35
(37)
RP55
(40)
RP75
(50)
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Key: ✓ available, x not generated, not available.

Format an alignment

  Seed
(6)
Full
(164)
Representative proteomes NCBI
(164)
Meta
(0)
RP15
(3)
RP35
(37)
RP55
(40)
RP75
(50)
Alignment:
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Sequence:
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We make all of our alignments available in Stockholm format. You can download them here as raw, plain text files or as gzip-compressed files.

  Seed
(6)
Full
(164)
Representative proteomes NCBI
(164)
Meta
(0)
RP15
(3)
RP35
(37)
RP55
(40)
RP75
(50)
Raw Stockholm Download   Download   Download   Download   Download   Download   Download    
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You can also download a FASTA format file containing the full-length sequences for all sequences in the full alignment.

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 HMMER3.

Pfam alignments:

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'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.

Note: You can also download the data file for the tree.

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: SCOP
Previous IDs: Enterotoxin_A;
Type: Domain
Author: Bateman A
Number in seed: 6
Number in full: 164
Average length of the domain: 208.20 aa
Average identity of full alignment: 43 %
Average coverage of the sequence by the domain: 47.94 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 19.6 19.6
Trusted cut-off 19.9 20.1
Noise cut-off 19.5 19.0
Model length: 260
Family (HMM) version: 12
Download: download the raw HMM for this family

Species distribution

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Structures

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 Enterotoxin_a domain has been found. There are 29 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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