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An enterotoxin is a protein exotoxin released by a microorganism that targets the intestines. [1] They can be chromosomally or plasmid encoded. [ 2 ] They are heat labile (> 60 °C), of low molecular weight and water-soluble.
(Ribosome structure is one of the most important differences between eukaryotes and prokaryotes, and, in a sense, these exotoxins are the bacterial equivalent of antibiotics such as clindamycin.) Some exotoxins act directly at the ribosome to inhibit protein synthesis. An example is Shiga toxin. Other toxins act at elongation factor-2.
The toxic activity of LPS was first discovered and termed endotoxin by Richard Friedrich Johannes Pfeiffer.He distinguished between exotoxins, toxins that are released by bacteria into the surrounding environment, and endotoxins, which are toxins "within" the bacterial cell and released only after destruction of the bacterial outer membrane. [11]
Different STs recognize distinct receptors on the surface of animal cells and thereby affect different intracellular signaling pathways. For example, STa enterotoxins bind and activate membrane-bound guanylate cyclase, which leads to the intracellular accumulation of cyclic GMP and downstream effects on several signaling pathways.
Endotoxins most commonly refer to the lipopolysaccharide (LPS) or lipooligosaccharide (LOS) that are in the outer plasma membrane of Gram-negative bacteria. The botulinum toxin , which is primarily produced by Clostridium botulinum and less frequently by other Clostridium species, is the most toxic substance known in the world. [ 1 ]
Endotoxin is a component (lipopolysaccharide (LPS)) of the cell wall of gram-negative bacteria. It is the lipid A part of this LPS which is toxic. [4] Lipid A is an endotoxin. Endotoxins trigger intense inflammation. They bind to receptors on monocytes causing the release of inflammatory mediators which induce degranulation. As part of this ...
Earlier research established TcdA strictly as an enterotoxin, and TcdB as a cytotoxin, but later both toxins were found to have the same mechanism of action. [6] To fully investigate the role of both toxins in pathogenesis of C. difficile infection, a gene knockout system in a hamster infection model was developed.
Microbiologists use many terms to describe Shiga toxin and differentiate more than one unique form. Many of these terms are used interchangeably.. Shiga toxin type 1 and type 2 (Stx-1 and 2) are the Shiga toxins produced by some E. coli strains.