SUPERFAMILY 1.75 HMM library and genome assignments server

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Bacterial enterotoxins superfamily

SCOP classification
Root:   SCOP hierarchy in SUPERFAMILY [ 0] (11)
Class:   All beta proteins [ 48724] (174)
Fold:   OB-fold [ 50198] (16)
Superfamily:   Bacterial enterotoxins [ 50203] (2)
Families:   Bacterial AB5 toxins, B-subunits [ 50204] (6)
  Superantigen toxins, N-terminal domain [ 50219] (15)

Superfamily statistics
Genomes (129) Uniprot 2018_03 genome PDB chains (SCOP 1.75)
Domains 928 1,876 73
Proteins 925 1,875 73

Functional annotation
General category Processes_EC
Detailed category Toxins/defense

Function annotation of SCOP domain superfamilies

InterPro annotation
Cross references IPR008992 SSF50203 Protein matches

Cholera toxin produced by Vibrio cholerae and heat-labile enterotoxin, produced by enterotoxigenic Escherichia coli, are AB5 heterohexamers, consisting of one A polypeptide and five identical B polypeptides, with an ADP-ribosylating A subunit and a GM1 receptor binding B pentamer. These toxins are among the most potent mucosal adjuvants known. The B pentamer is required for binding to the cell surface receptor ganglioside GM1. The A subunit can be proteolytically cleaved within the single disulphide-linked loop between two cysteine residues to produce the enzymatically active A1 polypeptide and the smaller A2 polypeptide that links fragment A1 to the B pentamer. Upon entry into enterocytes by endocytosis and following reduction and translocation, CT-A1 ADP-ribosylates a regulatory G-protein (Gsalpha), which leads to constitutive activation of adenylate cyclase, increased intracellular concentration of cyclic AMP, and secretion of fluid and electrolytes into the lumen of the small intestine [PubMed11395467].

All family members contain a common OB-fold, a five-stranded beta-sheet coiled to form a closed beta-barrel capped by an alpha-helix located between the third and fourth strands.

InterPro database

PDBeMotif information about ligands, sequence and structure motifs
Cross references PDB entries
Ligand binding statistics
Nucleic-acid binding statistics
Occurrence of secondary structure elements
Occurrence of small 3D structural motifs

PDBeMotif resource

Jump to [ Top of page · SCOP classification · InterPro annotation · PDBeMotif links · Functional annotation ]

Internal database links

Browse genome assignments for this superfamily. The SUPERFAMILY hidden Markov model library has been used to carry out SCOP domain assignments to all genomes at the superfamily level.

Alignments of sequences to 41 models in this superfamily are available by clicking on the 'Alignments' icon above. PDB sequences less than 40% identical are shown by default, but any other sequence(s) may be aligned. Select PDB sequences, genome sequences, or paste in or upload your own sequences.

Browse and view proteins in genomes which have different domain combinations including a Bacterial enterotoxins domain.

Examine the distribution of domain superfamilies, or families, across the major taxonomic kingdoms or genomes within a kingdom. This gives an immediate impression of how superfamilies, or families, are restricted to certain kingdoms of life.

Explore domain occurrence network where nodes represent genomes and edges are domain architectures (shared between genomes) containing the superfamily of interest.

There are 41 hidden Markov models representing the Bacterial enterotoxins superfamily. Information on how the models are built, and plots showing hydrophobicity, match emmission probabilities and insertion/deletion probabilities can be inspected.

Jump to [ Top of page · SCOP classification · InterPro annotation · PDBeMotif links · Functional annotation · Internal database links ]