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Encyclopedia > Exotoxins

An exotoxin is a soluble chemical excreted by a microorganism, including bacteria, fungi, algae, and protozoa. This is a type of toxin that is produced by bacteria and released into the bloodstream. These toxins can cause damage in the body by destroying cells or disrupting normal cellular metabolism. E. coli magnified 10,000 times. ... Phyla/Divisions Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Omnibacteria Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular, bacterium) are a major group of living organisms. ... Divisions Chytridiomycota Zygomycota Ascomycota Basidiomycota The Fungi (singular: fungus) are a large group of organisms ranked as a kingdom within the Domain Eukaryota. ... A seaweed (Laurencia) up close: the branches are multicellular and only about 1 mm thick. ... Wikisource has original 1911 Encyclopædia Britannica text related to: Protozoa Protozoa (in Greek proto = first and zoa = animal) are single-celled eukaryotes (organisms with nuclei) that show some characteristics usually associated with animals, most notably mobility and heterotrophy. ...

There are three main types of exotoxins:

  • toxins that act upon the extracellular matrix or connective tissue - this allows the further spread of bacteria and therefore the infection deeper into tissue regions.
  • A-B type toxins - the 'B'-subunit attaches to target regions on cell membranes, the 'A'-subunit tends to have an enzymatic function and enters through the membrane affecting the internal bio-mechanisms. Many toxins are classified as 'AB5' meaning that they contain one enzymatically active A-subunit and a pentamer of five identical B-subunits. Toxins of this type include cholera toxin, pertussis toxin, shiga toxin and heat-labile enterotoxin from E. coli.
  • Membrane damaging toxins - these toxins are designed primarily to puncture and disrupt the cellular membrane killing cells, a significant resulting example is that of Gangrene.

It has been suggested that gas gangrene be merged into this article or section. ...

See also

This microorganism-related article is a stub. You can help Wikipedia by expanding it.

  Results from FactBites:
Streptococcal Toxic-Shock Syndrome (5990 words)
Data suggest that this exotoxin and a number of staphylococcal toxins (toxic shock syndrome toxin-1 [TSST-1] and staphylococcal enterotoxins A, B, and C) can stimulate T-cell responses through their ability to bind to both the Class II major histocompatibility ability complex of antigen-presenting cells and the Vb region of the T-cell receptor (48).
Finally, genetic information coding for exotoxins A or C may be introduced to strains of GAS by certain bacteriophage; after lysogenic conversion, synthesis of exotoxin A would occur during growth of the streptococcus (31,59,60).
Characterization of a superantigen from a pathogenic strain of Streptococcus pyogenes.
  More results at FactBites »


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