Microbial toxin

from Wikipedia, the free encyclopedia
Molecular structure of botulinum toxin , the toxin of the bacterium Clostridium botulinum

Microbial toxin refers to a toxin produced by microorganisms (microbes), i.e. H. of bacteria , protists or fungi . A disease caused by microbial toxins is known as microbial toxinosis , sometimes even without the presence of living microorganisms.

properties

Microbial toxins mostly belong to the proteins , glycoproteins , proteolipids , glycolipids or polysaccharides . Protein-based microbial toxins often have enzymatic activity, which increases their effectiveness , since one toxin molecule can inactivate or activate several target molecules. The enzymatic activity often causes a post-translational modification . Microbial toxins are used by microorganisms to improve reproductive conditions, some of which are important virulence factors and aggravate the symptoms of an infectious disease . In addition, a cellular molecule can also be inhibited by a bond without an enzymatic effect . Often serve microbial toxins of the microorganisms by the destruction of cells in a host of improving the food supply or the destruction or inhibition of immune cells during an immune evasion . Some microbial toxins only work by activating immune cells without their own toxic effect, e.g. B. some endotoxins. Other microbial toxins can accumulate in food and lead to food poisoning, e.g. B. botulism .

In biochemistry , microbial toxins are used, among other things, to bind or modify the target molecules of the respective toxin, in the course of protein design to generate immunotoxins , as an adjuvant in experimental vaccines or as a transgene in oncolytic viruses . MvirDB is a database of microbial toxins.

Bacterial toxins

Bacterial toxins can be divided into endotoxins and exotoxins according to their occurrence .

Exotoxins

Exotoxins occur mainly outside the bacterial cell and are mostly secreted , e.g. As diphtheria toxin , tetanus toxin , cholera toxin , botulinum toxin , α-hemolysin , Clostridium perfringens α-toxin , exotoxin A , anthrax toxin , pertussis toxin , tracheal cytotoxin (TCT) from Bordetella pertussis , which dermonecrotic toxin of Bordetella parapertussis and B. bronchiseptica , Shiga toxin , the Shiga-like toxin 1 , Shiga-like toxin 2 , Pasteurella multocida toxin (PMT), cytolethal distending toxin (CDT) from Campylobacter coli , thermolabile hemolysin and thermostable direct hemolysin from Vibrio parahaemolyticus , the vacuolating one Cytotoxin from Helicobacter pylori and the pore-forming toxins , e.g. B. Leucocidine . Bacterial exotoxins are recorded in the DBETH database .

The toxins of the bacterium Clostridium botulinum , which lives anaerobically in the soil , are among the most poisonous known toxins and cause the clinical picture of botulism . Botulinum toxin is used, among other things, to treat hyperhidrosis and in cosmetic surgery to reduce expression lines.

Endotoxins

Endotoxins, on the other hand, are usually only released when the bacterium is destroyed in the course of an immune reaction or during cell disruption and are therefore components of the microbial cell wall or the outer membrane of gram-negative bacteria (e.g. lipopolysaccharides ). Superantigens and various PAMP endotoxins are e.g. B. in a sepsis or toxinosis, via an activation of the innate immune response pro-inflammatory and therefore medically relevant pyrogens , z. B. Lipopolysaccharides.

Toxins from mushrooms

Toxins secreted by living fungal cells usually have a lower molar mass compared to bacterial (protein-based) exotoxins . Aspergillus flavus produces aflatoxins , which are among the most potent mutagenic toxins. Analogous to the bacterial endotoxins, the polysaccharide zymosan , which activates the TLR-2 of the innate immune system , is released during cell death and degradation in yeast .

literature

  • Manfred J. Schmitt, Raffael Schaffrath: Microbial Protein Toxins . In: Topics in Current Genetics , Volume 11. Springer 2005. ISBN 978-3-540-23562-0 .
  • Otto Holst: Microbial Toxins - Methods and Protocols . In: Methods in Molecular Biology , Volume 739, Humana 2011. ISBN 978-1-61779-101-7 .
  • Donald G. Barceloux: Medical Toxicology of Natural Substances Foods, Fungi, Medicinal Herbs, Plants, and Venomous Animals. Wiley 2008. ISBN 9780471727613 .

Web links

Individual evidence

  1. ↑ Bruce Fisher, Richard P. Harvey, Pamela C. Champe: Microbiology (=  Lippincott's Illustrated Reviews Series ). 2nd Edition. Lippincott Williams & Wilkins, Hagerstown, MD 2006, ISBN 0-7817-8215-5 , pp. 348 .
  2. ↑ E. Lemichez, JT Barbieri: General aspects and recent advances on bacterial protein toxins. In: Cold Spring Harbor Perspectives in Medicine . Volume 3, number 2, February 2013, ISSN  2157-1422 , p. A013573, doi : 10.1101 / cshperspect.a013573 , PMID 23378599 .
  3. ↑ Langley et al .: Staphylococcal Immune Evasion Toxins . In: Microbial Toxins: Current Research and Future Trends . Caister Academic Press, 2009, ISBN 978-1-904455-44-8 .
  4. ↑ G. Schiavo, FG van der Goot: The bacterial toxin toolkit. In: Nature Reviews Molecular Cell Biology . Volume 2, Number 7, July 2001, ISSN  1471-0072 , pp. 530-537, doi : 10.1038 / 35080089 , PMID 11433367 . PDF .
  5. ↑ T. Proft T (Editor): Microbial Toxins: Current Research and Future Trends . Caister Academic Press, 2009, ISBN 978-1-904455-44-8 .
  6. ↑ Definition of bacterial toxin - NCI Dictionary of Cancer Terms . Retrieved December 13, 2008.
  7. ↑ CE Zhou, J. Smith, M. Lam, A. Zemla, MD Dyer, T. Slezak: MvirDB - a microbial database of protein toxins, virulence factors and antibiotic resistance genes for bio-defense applications. In: Nucleic Acids Research . Volume 35, Database issue, 2007, pp. D391-D394, ISSN  1362-4962 , doi : 10.1093 / nar / gkl791 , PMID 17090593 , PMC 1669772 (free full text).
  8. ↑ DM Gill: Bacterial toxins: a table of lethal amounts. In: Microbiological reviews. Volume 46, Number 1, March 1982, pp. 86-94, ISSN  0146-0749 , PMID 6806598 , PMC 373212 (free full text).
  9. ↑ A. Chakraborty, S. Ghosh, G. Chowdhary, U. Maulik, S. Chakrabarti: DBETH: a Database of Bacterial Exotoxins for Human. In: Nucleic acids research. Volume 40, Database issue, 2012, ISSN  1362-4962 , pp. D615-D620, doi : 10.1093 / nar / gkr942 , PMID 22102573 , PMC 3244994 (free full text).
  10. ↑ R. Kukreja, BR Singh: Botulinum Neurotoxins: Structure and Mechanism of Action . In: Microbial Toxins: Current Research and Future Trends . Caister Academic Press, 2009, ISBN 978-1-904455-44-8 .