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The effector proteins injected by the type III secretion apparatus of Yersinia into target cells are one example. Another group of intracellular toxins is the AB toxins . The 'B'-subunit ( b inding ) attaches to target regions on cell membranes, the 'A'-subunit ( a ctive ) enters through the membrane and possesses enzymatic function that ...
Diphtheria toxin is a single polypeptide chain of 535 amino acids consisting of two subunits linked by disulfide bridges, known as an A-B toxin. Binding to the cell surface of the B subunit (the less stable of the two subunits) allows the A subunit (the more stable part of the protein) to penetrate the host cell. [4]
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.
The partner proteins in these combinations may belong to different structural groups, depending on the individual toxin: two Toxin_10 proteins (BinA and BinB) act together in the Bin mosquitocidal toxin of Lysinibacillus sphaericus; [14] the Toxin_10 Cry49 is co-dependent on the 3-domain toxin family member Cry48 for its activity against Culex ...
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.
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 ...
Often the toxin and antitoxin are encoded on opposite strands of DNA. The 5' or 3' overlapping region between the two genes is the area involved in complementary base-pairing, usually with between 19–23 contiguous base pairs. [39] Toxins of type I systems are small, hydrophobic proteins that confer toxicity by damaging cell membranes. [1]
Proteins form by amino acids undergoing condensation reactions, in which the amino acids lose one water molecule per reaction in order to attach to one another with a peptide bond. By convention, a chain under 30 amino acids is often identified as a peptide, rather than a protein. [1]