The Pseudomonas exotoxin (or exotoxin A) is an exotoxin produced by Pseudomonas aeruginosa.
It inhibits elongation factor-2. It does so by ADP-ribosylation of EF2. This then causes the elongation of polypeptides to cease.(The mechanism of the toxin is similar to that of Diphtheria toxin.)
It has been investigated as a treatment for hepatitis B and cancer.
References
Pseudomonas exotoxin Wikipedia(Text) CC BY-SA