33] Shiga toxin as inhibitor of protein synthesis

Abstract

Publisher Summary This chapter describes the Shiga toxin as inhibitor of protein synthesis. Shiga toxin, a protein produced by all strains of Shigella dysenteriae , is a potent inhibitor of eukaryotic protein synthesis. The molecule is composed of two distinct polypeptide subunits, both of which play an essential role in mediating inhibition of cellular protein synthesis caused by the addition of toxin to intact mammalian cells. Two bacterial toxins, pseudomonas exotoxin A and diphtheria toxin are known to inhibit protein synthesis by catalyzing the transfer of the adenosine diphosphate moiety from nicotinamide adenine dinucleotide (NAD) to the protein synthesis elongation factor (EF-2). Shiga toxin is a lethal cytotoxin to a limited number of tissue culture cell lines. Susceptible cells are primate epithelial cells, including the human cervical carcinoma-derived HeLa line, and the African Green monkey kidney Vero cell line. Many epithelial and nonepithelial cell lines are resistant to Shiga toxin. The toxin A subunit is responsible for the inhibition of protein synthesis caused by the intact toxin.