Structure of exotoxin A of Pseudomonas aeruginosa at 3.0-Angstrom resolution.

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Abstract
Exotoxin A of Pseudomonas aeruginosa is a secreted bacterial toxin capable of translocating a catalytic domain into mammalian cells and inhibiting protein synthesis by the ADP-ribosylation of cellular elongation factor 2. The protein is a single polypeptide chain of 613 amino acids. The X-ray crystallographic structure of exotoxin A, determined to 3.0-.ANG. resolution, shows the following: an amino-terminal domain, composed primarily of antiparallel .beta.-structure and comprising approximately half of the molecule; a middle domain composed of .alpha.-helices; and a carboxyl-terminal domain comprising approximately one-third of the molecule. The carboxyl-terminal domain is the ADP-ribosyltransferase of the toxin. The other two domains are presumably involved in cell receptor binding and membrane translocation.