World Library  
Flag as Inappropriate
Email this Article

Shiga toxin

Article Id: WHEBN0000174232
Reproduction Date:

Title: Shiga toxin  
Author: World Heritage Encyclopedia
Language: English
Subject: Escherichia coli O104:H4, Exotoxin, AB5 toxin, Shiga-like toxin, List of notifiable diseases
Collection: Ab5 Toxins
Publisher: World Heritage Encyclopedia

Shiga toxin

Ribbon diagram of Shiga toxin (Stx) from S. dysenteriae. From ​.

Shiga toxins are a family of related toxins with two major groups, Stx1 and Stx2, expressed by genes considered to be part of the genome of lambdoid prophages.[1] The toxins are named for Kiyoshi Shiga, who first described the bacterial origin of dysentery caused by Shigella dysenteriae. The most common sources for Shiga toxin are the bacteria S. dysenteriae and the shigatoxigenic group of Escherichia coli (STEC), which includes serotypes O157:H7, O104:H4, and other enterohemorrhagic E. coli (EHEC).[2][3]


  • Nomenclature 1
  • Mechanism 2
  • Structure 3
  • See also 4
  • References 5
  • External links 6


Microbiologists use many terms to describe Shiga toxin and differentiate more than one unique form. Many of these terms are used interchangeably.

  1. Shiga toxin (Stx) - true Shiga toxin - is produced by Shigella dysenteriae.
  2. Shiga-like toxins 1 and 2 (SLT-1 and 2 or Stx-1 and 2) are the Shiga toxins produced by some E. coli strains. Stx-1 differs from Stx by only one amino acid. Stx-2 shares 56% sequence identity with Stx-1.
  3. Cytotoxins - an archaic denotation for Stx - is used in a broad sense.
  4. Verocytotoxins/verotoxins - a seldom-used term for Stx - is from the hypersensitivity of Vero cells to Stx.


Shiga toxins act to inhibit protein synthesis within target cells by a mechanism similar to that of ricin toxin produced by Ricinus communis.[4] After entering a cell via a macropinosome,[5] the protein functions as an N-glycosidase, cleaving a specific adenine nucleobase from the 28S RNA of the 60S subunit of the ribosome, thereby halting protein synthesis.[6]


The toxin has two subunits—designated A (mol. wt. 32000 D) and B (mol. wt. 7700 D)—and is one of the AB5 toxins. The B subunit is a pentamer that binds to specific glycolipids on the host cell, specifically globotriaosylceramide (Gb3). Following this, the A subunit is internalised and cleaved into two parts. The A1 component then binds to the ribosome, disrupting protein synthesis. Stx-2 has been found to be about 400 times more toxic (as quantified by LD50 in mice) than Stx-1.

Gb3 is, for unknown reasons, present in greater amounts in renal epithelial tissues, to which the renal toxicity of Shiga toxin may be attributed. Gb3 is also found in central nervous system neurons and endothelium, which may lead to neurotoxicity.[7] Stx-2 is also known to increase the expression of its receptor GB3 and cause neuronal dysfunctions.[8]

The toxin requires highly specific receptors on the cells' surface 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.[9]

See also


  1. ^ Friedman D, Court D (2001). "Bacteriophage lambda: alive and well and still doing its thing". Current Opinion in Microbiology 4 (2): 201–7.  
  2. ^ Beutin L (2006). "Emerging enterohaemorrhagic Escherichia coli, causes and effects of the rise of a human pathogen". J Vet Med B Infect Dis Vet Public Health 53 (7): 299–305.  
  3. ^ Spears; et al. (2006). "A comparison of Enteropathogenic and enterohaemorragic E.coli pathogenesis". FEMS Microbiology Letters: 187–202. 
  4. ^ Sandvig K, van Deurs B (2000). "Entry of ricin and Shiga toxin into cells: molecular mechanisms and medical perspectives". The EMBO Journal 19 (22): 5943–50.  
  5. ^ Lukyanenko, V.; Malyukova, I.; Hubbard, A.; Delannoy, M.; Boedeker, E.; Zhu, C.; Cebotaru, L.; Kovbasnjuk, O. (2011). "Enterohemorrhagic Escherichia coli infection stimulates Shiga toxin 1 macropinocytosis and transcytosis across intestinal epithelial cells". AJP: Cell Physiology 301 (5): C1140–C1149.  
  6. ^ Sandvig K, Bergan J, Dyve A, Skotland T, Torgersen M.L. (2010). "Endocytosis and retrograde transport of Shiga toxin". Toxicon. 56 Suppl 7: 1181–1185.  
  7. ^ Obata F, Tohyama K, Bonev AD, Kolling GL, Keepers TR, Gross LK, Nelson MT, Sato S, Obrig TG (2008). "Shiga Toxin 2 Affects the Central Nervous System through Receptor Globotriaosylceramide Localized to Neurons". J Infect Dis 198 (9): 1398–1406.  
  8. ^ Tironi-Farinati C, Loidl CF, Boccoli J, Parma Y, Fernandez-Miyakawa ME, Goldstein J. (2010). "Intracerebroventricular Shiga toxin 2 increases the expression of its receptor globotriaosylceramide and causes dendritic abnormalities". J Neuroimmunol 222 (1–2): 48–61.  
  9. ^ Asakura H, Makino S, Kobori H, Watarai M, Shirahata T, Ikeda T, Takeshi K (2001). "Phylogenetic diversity and similarity of active sites of Shiga toxin (stx) in Shiga toxin-producing Escherichia coli (STEC) isolates from humans and animals". Epidemiol Infect 127 (1): 27–36.  

External links

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.