Summary: Clostridial binary toxin B/anthrax toxin PA
This is the Wikipedia entry entitled "AB toxin". More...
The Wikipedia text that you see displayed here is a download from Wikipedia. This means that the information we display is a copy of the information from the Wikipedia database. The button next to the article title ("Edit Wikipedia article") takes you to the edit page for the article directly within Wikipedia. You should be aware you are not editing our local copy of this information. Any changes that you make to the Wikipedia article will not be displayed here until we next download the article from Wikipedia. We currently download new content on a nightly basis.
Does Pfam agree with the content of the Wikipedia entry ?
Pfam has chosen to link families to Wikipedia articles. In some case we have created or edited these articles but in many other cases we have not made any direct contribution to the content of the article. The Wikipedia community does monitor edits to try to ensure that (a) the quality of article annotation increases, and (b) vandalism is very quickly dealt with. However, we would like to emphasise that Pfam does not curate the Wikipedia entries and we cannot guarantee the accuracy of the information on the Wikipedia page.
Editing Wikipedia articles
Before you edit for the first time
Wikipedia is a free, online encyclopedia. Although anyone can edit or contribute to an article, Wikipedia has some strong editing guidelines and policies, which promote the Wikipedia standard of style and etiquette. Your edits and contributions are more likely to be accepted (and remain) if they are in accordance with this policy.
You should take a few minutes to view the following pages:
How your contribution will be recorded
Anyone can edit a Wikipedia entry. You can do this either as a new user or you can register with Wikipedia and log on. When you click on the "Edit Wikipedia article" button, your browser will direct you to the edit page for this entry in Wikipedia. If you are a registered user and currently logged in, your changes will be recorded under your Wikipedia user name. However, if you are not a registered user or are not logged on, your changes will be logged under your computer's IP address. This has two main implications. Firstly, as a registered Wikipedia user your edits are more likely seen as valuable contribution (although all edits are open to community scrutiny regardless). Secondly, if you edit under an IP address you may be sharing this IP address with other users. If your IP address has previously been blocked (due to being flagged as a source of 'vandalism') your edits will also be blocked. You can find more information on this and creating a user account at Wikipedia.
If you have problems editing a particular page, contact us at email@example.com and we will try to help.
The community annotation is a new facility of the Pfam web site. If you have problems editing or experience problems with these pages please contact us.
AB toxin Edit Wikipedia article
crystal structure of the enzymatic componet of iota-toxin from clostridium perfringens with nadh
crystal structure of the anthrax toxin protective antigen heptameric prepore
The AB toxins are two-component protein complexes secreted by a number of pathogenic bacteria. They can be classified as Type III toxins because they interfere with internal cell function. They are named AB toxins due to their components: the "A" component is usually the "active" portion, and the "B" component is usually the "binding" portion. The "A" subunit possesses enzyme activity, and is transferred to the host cell following a conformational change in the membrane-bound transport "B" subunit. Among the toxins produced by certain Clostridium spp. are the binary exotoxins. These proteins consist of two independent polypeptides, which correspond to the A/B subunit moieties. The enzyme component (A) enters the cell through endosomes produced by the oligomeric binding/translocation protein (B), and prevents actin polymerisation through ADP-ribosylation of monomeric G-actin.
Members of the "A" binary toxin family include C. perfringens iota toxin Ia, C. botulinum C2 toxin CI, and Clostridium difficile ADP-ribosyltransferase . Other homologous proteins have been found in Clostridium spiroforme.
Members of the "B" binary toxin family include the Bacillus anthracis protective antigen (PA) protein, most likely due to a common evolutionary ancestor. B. anthracis, a large Gram-positive spore-forming rod, is the causative agent of anthrax. Its two virulence factors are the poly-D-glutamate polypeptide capsule, and the actual anthrax exotoxin. The toxin comprises three factors: the protective antigen (PA); the oedema factor (EF); and the lethal factor (LF). Each is a thermolabile protein of ~80kDa. PA forms the "B" part of the exotoxin and allows passage of the "A" moiety (consisting of EF and LF) into target cells. PA protein forms the central part of the complete anthrax toxin, and translocates the B moiety into host cells after assembling as a heptamer in the membrane.
The AB5 toxins are usually considered a type of AB toxin, characterized by B pentamers. Less commonly, the term "AB toxin" is used to emphasize the monomeric character of the B component.
- "Bacterial Pathogenesis: Bacterial Factors that Damage the Host - Producing Exotoxins - A-B Toxins". Retrieved 2008-12-13.
- De Haan L, Hirst TR (2004). "Cholera toxin: a paradigm for multi-functional engagement of cellular mechanisms (Review)". Mol. Membr. Biol. 21 (2): 77–92. doi:10.1080/09687680410001663267. PMID 15204437.
- Perelle S, Gibert M, Boquet P, Popoff MR (December 1993). "Characterization of Clostridium perfringens iota-toxin genes and expression in Escherichia coli". Infect. Immun. 61 (12): 5147–56. PMC 281295. PMID 8225592.
- Fujii N, Kubota T, Shirakawa S, Kimura K, Ohishi I, Moriishi K, Isogai E, Isogai H (March 1996). "Characterization of component-I gene of botulinum C2 toxin and PCR detection of its gene in clostridial species". Biochem. Biophys. Res. Commun. 220 (2): 353–9. doi:10.1006/bbrc.1996.0409. PMID 8645309.
- Stubbs S, Rupnik M, Gibert M, Brazier J, Duerden B, Popoff M (May 2000). "Production of actin-specific ADP-ribosyltransferase (binary toxin) by strains of Clostridium difficile". FEMS Microbiol. Lett. 186 (2): 307–12. PMID 10802189.
- Pezard C, Berche P, Mock M (October 1991). "Contribution of individual toxin components to virulence of Bacillus anthracis". Infect. Immun. 59 (10): 3472â7. PMC 258908. PMID 1910002.
- Welkos SL, Lowe JR, Eden-McCutchan F, Vodkin M, Leppla SH, Schmidt JJ (September 1988). "Sequence and analysis of the DNA encoding protective antigen of Bacillus anthracis". Gene 69 (2): 287–300. doi:10.1016/0378-1119(88)90439-8. PMID 3148491.
Clostridial binary toxin B/anthrax toxin PA Provide feedback
The N-terminal region of this family contains a calcium-binding motif that may be an EF-hand.
External database links
This tab holds annotation information from the InterPro database.
InterPro entry IPR003896
A large group of bacterial exotoxins are referred to as "A/B toxins", essentially because they are formed from two subunits [PUBMED:8225592]. The "A" subunit possesses enzyme activity, and is transferred to the host cell following a conformational change in the membrane-bound transport "B" subunit. Clostridial species are one of the major causes of food poisoning/gastro-intestinal illnesses. They are Gram-positive, spore-forming rods that occur naturally in the soil [PUBMED:8225592]. Among the toxins produced by certain Clostridium spp. are the binary exotoxins. These proteins consist of two independent polypeptides, which correspond to the A/B subunit moieties. The enzyme component (A) enters the cell through endosomes produced by the oligomeric binding/translocation protein (B), and prevents actin polymerisation through ADP-ribosylation of monomeric G-actin [PUBMED:8225592, PUBMED:9659689, PUBMED:10802189].
Members of the "B" binary toxin family also include the Bacillus anthracis protective antigen (PA) protein [PUBMED:8225592], most likely due to a common evolutionary ancestor. B. anthracis, a large Gram-positive spore-forming rod, is the causative agent of anthrax. Its two virulence factors are the poly-D-glutamate polypeptide capsule, and the actual anthrax exotoxin [PUBMED:1910002]. The toxin comprises three factors: the protective antigen (PA); the oedema factor (EF); and the lethal factor (LF). Each is a thermolabile protein of ~80kDa. PA forms the "B" part of the exotoxin and allows passage of the "A" moiety (consisting of EF and LF) into target cells. PA protein forms the central part of the complete anthrax toxin, and translocates the B moiety into host cells after assembling as a heptamer in the membrane [PUBMED:1910002, PUBMED:3148491].
|Cellular component||extracellular region (GO:0005576)|
|Biological process||pathogenesis (GO:0009405)|
- the number of sequences which exhibit this architecture
a textual description of the architecture, e.g. Gla, EGF x 2, Trypsin.
This example describes an architecture with one
Gladomain, followed by two consecutive
EGFdomains, and finally a single
- the UniProt description of the protein sequence
- the number of residues in the sequence
- the Pfam graphic itself.
Loading domain graphics...
We make a range of alignments for each Pfam-A family:
- the curated alignment from which the HMM for the family is built
- the alignment generated by searching the sequence database using the HMM
- Representative Proteomes (RPs) at 15%, 35%, 55% and 75% co-membership thresholds
- alignment generated by searching the NCBI sequence database using the family HMM
- alignment generated by searching the metagenomics sequence database using the family HMM
You can see the alignments as HTML or in three different sequence viewers:
- Pfam viewer
- an HTML-based viewer that uses DAS to retrieve alignment fragments on request
1Cannot generate PP/Heatmap alignments for seeds; no PP data available
Key: available, not generated, — not available.
Format an alignment
If you find these logos useful in your own work, please consider citing the following article:
Note: You can also download the data file for the tree.
Curation and family details
|Number in seed:||8|
|Number in full:||100|
|Average length of the domain:||353.70 aa|
|Average identity of full alignment:||41 %|
|Average coverage of the sequence by the domain:||51.40 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||9|
|Download:||download the raw HMM for this family|
Weight segments by...
Change the size of the sunburst
selected sequences to HMM
a FASTA-format file
- 0 sequences
- 0 species
How the sunburst is generated
Colouring and labels
Anomalies in the taxonomy tree
Missing taxonomic levels
Unmapped species names
Too many species/sequences
The tree shows the occurrence of this domain across different species. More...
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
- expand/collapse the tree or expand it to a given depth
- select a sub-tree or a set of species within the tree and view them graphically or as an alignment
- save a plain text representation of the tree
There are 2 interactions 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 Binary_toxB domain has been found. There are 59 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.
Loading structure mapping...