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The deactivated exotoxins are called toxoids and they are not harmful to somatic cells. An exotoxin is a toxin secreted by bacteria. [1] An exotoxin can cause damage to the host by destroying cells or disrupting normal cellular metabolism. They are highly potent and can cause major damage to the host.
The Pseudomonas exotoxin (or exotoxin A) is an exotoxin produced by Pseudomonas aeruginosa. [1] Vibrio cholerae produces a similar protein called the Cholix toxin 2] It inhibits elongation factor-2. It does so by ADP-ribosylation of EF2 using NAD+. This then causes the elongation of polypeptides to cease.
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.
A potent three-protein virulence factor produced by Bacillus anthracis, called anthrax toxin, plays a key role in anthrax pathogenesis. Exotoxins are extremely immunogenic and trigger the humoral response (antibodies target the toxin). Exotoxins are also produced by some fungi as a competitive resource.
Exotoxin activity can be separated into specific cytotoxic activity or broad cytotoxic activity based on whether the toxin targets specific cell types or various cell types and tissues, respectively. Lethal toxins refers to the group of toxins that are the obvious agents responsible for death associated with the infection.
Anthrax is a disease caused by Bacillus anthracis, a spore-forming, Gram positive, rod-shaped bacterium (Fig. 1).The lethality of the disease is caused by the bacterium's two principal virulence factors: (i) the polyglutamic acid capsule, which is anti-phagocytic, and (ii) the tripartite protein toxin, called anthrax toxin.
Pertussis toxin is an exotoxin with six subunits (named S1 through S5—each complex contains two copies of S4). [12] [13] The subunits are arranged in A-B structure: the A component is enzymatically active and is formed from the S1 subunit, while the B component is the receptor-binding portion and is made up of subunits S2–S5. [13]
It is slightly unusual in that it combines the A and B parts in the same protein chain: the pre-toxin is cleaved into two parts, then the two parts are joined by a disulfide bond. [5] The exotoxin A of Pseudomonas aeruginosa is another example of an AB toxin that targets the eEF2. The "A" part is structually similar to the DT "A" part; the "B ...