ABSTRACT
In 1968, diphtheria toxin was shown to catalyze the transfer of the ADPribose portion of NAD into covalent linkage with mammalian elongation factor 2 (EF2). EF2 is a cytoplasmic protein which functions in the translocation step of protein synthesis and inactivation of this enzyme ultimately results in cessation of protein synthesis and cell death. The chapter details the toxins produced by at least four different bacteria, all of which catalyze the ADPribosylation of a target protein. These toxins have been shown to be either prime or contributing factors in the pathogenesis of the infections caused by the organisms producing them and these toxins represent one of the unique areas where the biochemical basis for virulence is understood. Cholera toxin and the heat labile toxin of E. coli exert their effects on cells through the activation of adenylate cyclase and the elevation of intracellular cAMP levels.
