Please note: this site relies heavily on the use of javascript. Without a javascript-enabled browser, this site will not function correctly. Please enable javascript and reload the page, or switch to a different browser.
156  structures 1  species 2  interactions 1  sequence 1  architecture

Family: SLT_beta (PF02258)

Summary: Shiga-like toxin beta subunit

Pfam includes annotations and additional family information from a range of different sources. These sources can be accessed via the tabs below.

This is the Wikipedia entry entitled "Shiga-like toxin". More...

Shiga-like toxin Edit Wikipedia article

Shiga-like toxin beta subunit
Symbol SLT_beta
Pfam PF02258
InterPro IPR003189
SCOP 2bos
TCDB 1.C.54

Shiga-like toxin, also known as verotoxin[1][2] and verocytotoxin, is a toxin generated by some strains of Escherichia coli (but see below).[3] It is named for its similarity to the AB5-type Shiga toxin produced by the bacteria Shigella dysenteriae (see Vero cell).

There are two types, known as SLT1 and SLT2.[4]


In 1977, researchers in Ottawa, Ontario discovered the Shiga toxin normally produced by Shigella dysenteriae in a line of E. coli.[5] The E. coli version of the toxin was named "verotoxin" because of its ability to kill Vero cells (African green monkey kidney cells) in culture. Shortly after, the verotoxin was referred to as Shiga-like toxin because of its similarities to Shiga toxin.

It has been suggested by some researchers that the gene coding for Shiga-like toxin comes from a toxin-converting lambdoid bacteriophage, such as H-19B or 933W, inserted into the bacteria's chromosome via transduction.[6] Phylogenetic studies of the diversity of E. coli suggest that it may have been relatively easy for Shiga toxin to transduce into certain strains of E. coli, because Shigella is itself a subgenus of Escherichia; in fact, some strains traditionally considered E. coli (including those that produce this toxin) in fact belong to this lineage. Being closer relatives of Shigella dysenteriae than of the typical E. coli, it is not at all unusual that toxins similar to that of S. dysenteriae are produced by these strains. As microbiology advances, the historical variation in nomenclature (which arose because of gradually advancing science in multiple places) is increasingly giving way to recognizing all of these molecules as "versions of the same toxin" rather than "different toxins."[7]:2-3


As with Shiga toxin, the toxin requires highly specific receptors on the cells' surface in order to attach and enter the cell; species such as cattle, swine, and deer which do not carry these receptors may harbor toxigenic bacteria without any ill effect, shedding them in their feces, from where they may be spread to humans.

Clinical significance

The Shiga-like toxin is associated with hemolytic-uremic syndrome.

Structure and mechanism

SLT2 from Escherichia coli O157:H7. The A subunit is shown in red (top), and the B subunits, forming a pentamer, in different shades of blue (bottom). From PDB: 1R4P​.


The toxin is a multisubunit protein made up of one molecule of A subunit (32,000 molecular weight) responsible for the toxic action of the protein, and five molecules of the B subunit (7,700 molecular weight) responsible for binding to a specific cell type.[7][8]

Mechanism of action

The toxin acts on the lining of the blood vessels, the vascular endothelium. The B subunits of the toxin bind to a component of the cell membrane known as glycolipid globotriaosylceramide (Gb3).[9] Binding of the subunit B to Gb3 causes induction of narrow tubular membrane invaginations, which drives formation of inward membrane tubules for the bacterial uptake into the cell. These tubules are essential for uptake into the host cell.[10] When the protein is inside the cell, the A subunit interacts with the ribosomes to inactivate them. The A subunit of Shiga toxin is an N-glycosidase that modifies the RNA component of the ribosome to inactivate it and so bring a halt to protein synthesis leading to the death of the cell. The vascular endothelium has to continually renew itself, so this killing of cells leads to a breakdown of the lining and to hemorrhage.[clarification needed] The first response is commonly a bloody diarrhea. This is because Shiga toxin is usually taken in with contaminated food or water.

The toxin is effective against small blood vessels, such as found in the digestive tract, the kidney, and lungs, but not against large vessels such as the arteries or major veins. A specific target for the toxin appears to the vascular endothelium of the glomerulus. This is the filtering structure that is a key to the function of the kidney. Destroying these structures leads to kidney failure and the development of the often deadly and frequently debilitating hemolytic uremic syndrome. Food poisoning with Shiga toxin often also has effects on the lungs and the nervous system.

See also


  1. ^ Beutin L; Geier D; Steinrück H; Zimmermann S; Scheutz F (September 1993). "Prevalence and some properties of verotoxin (Shiga-like toxin)-producing Escherichia coli in seven different species of healthy domestic animals". Journal of clinical microbiology. 31 (9): 2483–8. PMC 265781Freely accessible. PMID 8408571. 
  2. ^ Bitzan M; Richardson S; Huang C; Boyd B; Petric M; Karmali MA (August 1994). "Evidence that verotoxins (Shiga-like toxins) from Escherichia coli bind to P blood group antigens of human erythrocytes in vitro". Infection and immunity. 62 (8): 3337–47. PMC 302964Freely accessible. PMID 8039905. 
  3. ^ Giraldi R; Guth BE; Trabulsi LR (June 1990). "Production of Shiga-like toxin among Escherichia coli strains and other bacteria isolated from diarrhea in São Paulo, Brazil". Journal of clinical microbiology. 28 (6): 1460–2. PMC 267957Freely accessible. PMID 2199511. 
  4. ^ Zhu Q; Li L; Guo Z; Yang R (June 2002). "Identification of Shiga-like toxin Escherichia coli isolated from children with diarrhea by polymerase chain reaction". Chin. Med. J. 115 (6): 815–8. PMID 12123543. 
  5. ^ Konowalchuk J; Speirs J; Stavric S (1977). "Vero response to a cytotoxin of Escherichia coli". Infect. Immun. 18 (3): 775–9. PMC 421302Freely accessible. PMID 338490. 
  6. ^ Satoshi MIZUTANI; Naoki NAKAZONO & Yoshinobu SUGINO (1999). "The So-called Chromosomal Verotoxin Genes are Actually Carried by Defective Prophages". DNA Research. 6 (2): 141–143. PMID 10382973. doi:10.1093/dnares/6.2.141. 
  7. ^ a b Silva, Christopher J.; Brandon, David L.; Skinner, Craig B.; He, Xiaohua; et al. (2017), "Chapter 3: Structure of Shiga toxins and other AB5 toxins", Shiga toxins: A Review of Structure, Mechanism, and Detection, Springer, ISBN 978-3319505800. 
  8. ^ Stein PE; Boodhoo A; Tyrrell GJ; Brunton JL; Read RJ (February 1992). "Crystal structure of the cell-binding B oligomer of verotoxin-1 from E. coli". Nature. 355 (6362): 748–50. PMID 1741063. doi:10.1038/355748a0. 
  9. ^ Kaper, JB; Nataro, JP; Mobley, HL (Feb 2004). "Pathogenic Escherichia coli.". Nature Reviews. Microbiology. 2 (2): 123–40 [129]. PMID 15040260. doi:10.1038/nrmicro818. 
  10. ^ Römer W, Berland L, Chambon V, et al. (November 2007). "Shiga toxin induces tubular membrane invaginations for its uptake into cells". Nature. 450 (7170): 670–5. PMID 18046403. doi:10.1038/nature05996. 

External links

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.

Shiga-like toxin beta subunit Provide feedback

This family represents the B subunit of shiga-like toxin (SLT or verotoxin) produced by some strains of E.coli associated with hemorrhagic colitis and hemolytic uremic syndrome. SLT's are composed of one enzymatic A subunit and five cell binding B subunits.

Literature references

  1. Ling H, Pannu NS, Boodhoo A, Armstrong GD, Clark CG, Brunton JL, Read RJ; , Structure Fold Des 2000;8:253-264.: A mutant Shiga-like toxin IIe bound to its receptor Gb(3): structure of a group II Shiga-like toxin with altered binding specificity. PUBMED:10745005 EPMC:10745005

External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR003189

This family represents the B subunit of shiga-like toxin (SLT or verotoxin) produced by some strains of Escherichia coli associated with hemorrhagic colitis and hemolytic uremic syndrome. SLT s are composed of one enzymatic A subunit and five cell binding B subunits [PUBMED:10745005].

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...

Loading domain graphics...

Pfam Clan

This family is a member of clan OB_enterotoxin (CL0658), which has the following description:

This superfamily contains OB-fold domains found within bacterial enterotoxins. According to the SCOP and ECOD databases these domains are distinct from Clan:CL0021.

The clan contains the following 7 members:

Enterotoxin_b Pertus-S4-tox Pertus-S5-tox Pertussis_S2S3 SLT_beta SSL_OB Stap_Strp_toxin


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, the UniProtKB sequence database, the NCBI sequence database, and our metagenomics sequence database. More...

View options

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.

Representative proteomes UniProt
Jalview View  View        View  View  View   
HTML View  View               
PP/heatmap 1 View               

1Cannot generate PP/Heatmap alignments for seeds; no PP data available

Key: ✓ available, x not generated, not available.

Format an alignment

Representative proteomes UniProt

Download options

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.

Representative proteomes UniProt
Raw Stockholm Download   Download         Download   Download   Download    
Gzipped Download   Download         Download   Download   Download    

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

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...


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: Pfam-B_3684 (release 5.2)
Previous IDs: none
Type: Domain
Author: Bateman A, Mian N
Number in seed: 1
Number in full: 1
Average length of the domain: 70.00 aa
Average identity of full alignment: 100 %
Average coverage of the sequence by the domain: 78.65 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 26740544 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 21.1 21.1
Trusted cut-off 21.6 178.9
Noise cut-off 20.7 20.6
Model length: 70
Family (HMM) version: 15
Download: download the raw HMM for this family

Species distribution

Sunburst controls


Weight segments by...

Change the size of the sunburst


Colour assignments

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


Align selected sequences to HMM

Generate a FASTA-format file

Clear selection

This visualisation provides a simple graphical representation of the distribution of this family across species. You can find the original interactive tree in the adjacent tab. More...

Loading sunburst data...

Tree controls


The tree shows the occurrence of this domain across different species. More...


Please note: for large trees this can take some time. While the tree is loading, you can safely switch away from this tab but if you browse away from the family page entirely, the tree will not be loaded.


There are 2 interactions for this family. More...

RIP SLT_beta


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 SLT_beta domain has been found. There are 156 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.

Loading structure mapping...