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An exotoxin is a toxin secreted by bacteria. [1] ... However, induction of cell lysis may not be the primary function of the toxins during infection. At low ...
SpeB was identified in 1919 as an ectoenzyme secreted by certain strains of streptococci. [11] It was originally studied as two separate toxins, streptococcal pyrogenic exotoxin B and streptococcal cysteine proteinase, until it was shown that both proteins were encoded by the speB gene and that the attributed pyrogenic activities were due to contamination by SpeA and SpeC.
Diphtheria toxin is an exotoxin secreted mainly by Corynebacterium diphtheriae but also by Corynebacterium ulcerans and Corynebacterium pseudotuberculosis, the pathogenic bacterium that causes diphtheria. The toxin gene is encoded by a prophage [annotation 1] called corynephage β.
Lysogens can remain in the lysogenic cycle for many generations but can switch to the lytic cycle at any time via a process known as induction. [8] During induction, prophage DNA is excised from the bacterial genome and is transcribed and translated to make coat proteins for the virus and regulate lytic growth. [8] Lysogenic Cycle [9]
A toxoid is an inactivated toxin (usually an exotoxin) whose toxicity has been suppressed either by chemical or heat treatment, while other properties, typically immunogenicity, are maintained. [1] Toxins are secreted by bacteria, whereas toxoids are altered form of toxins; toxoids are not secreted by bacteria.
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 ]
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" part is located to the N-terminal direction to the "A" part, unlike DT.
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.