World Library  
Flag as Inappropriate
Email this Article

Shiga-like toxin

Article Id: WHEBN0000174231
Reproduction Date:

Title: Shiga-like toxin  
Author: World Heritage Encyclopedia
Language: English
Subject: Verocytotoxin, AB5 toxins, Verotoxin-producing Escherichia coli, Vero cell, Escherichia coli O157:H7
Publisher: World Heritage Encyclopedia

Shiga-like toxin

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] 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]


  • History 1
  • Transmission 2
  • Clinical significance 3
  • Structure and mechanism 4
    • Structure 4.1
    • Mechanism of action 4.2
  • Source of toxin gene 5
  • See also 6
  • References 7
  • External links 8



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 ​.


The toxin is a multisubunit protein made up 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.

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).[5] 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.[6] 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. 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.

Source of toxin gene

It has been suggested by some researchers that the gene coding for Shiga-like toxin comes from a toxin-converting lambdoid prophage, such as H-19B or 933W, inserted into the bacteria's chromosome via transduction.[7]

See also


  • [8]
  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.  
  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.  
  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.  
  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.  
  5. ^ Kaper, JB; Nataro, JP; Mobley, HL (Feb 2004). "Pathogenic Escherichia coli.". Nature reviews. Microbiology 2 (2): 123–40 [129].  
  6. ^ 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.  
  7. ^ Satoshi MIZUTANI, Naoki NAKAZONO, and Yoshinobu SUGINO (1999). "The So-called Chromosomal Verotoxin Genes are Actually Carried by Defective Prophages". Dna Research 6 (2): 141–143.  
  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.  

External links

  • Shiga-Like Toxin I at the US National Library of Medicine Medical Subject Headings (MeSH)
  • Shiga-Like Toxin II at the US National Library of Medicine Medical Subject Headings (MeSH)
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from World Library are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.