Shigella dysenteriae is the pathogen responsible for the severe form of dysentery in humans. It produces Shiga toxin, the prototype of a family of closely related bacterial protein toxins. We have determined the structure of the holotoxin, an AB5 hexamer, by X-ray crystallography ...
Shigella dysenteriae is the pathogen responsible for the severe form of dysentery in humans. It produces Shiga toxin, the prototype of a family of closely related bacterial protein toxins. We have determined the structure of the holotoxin, an AB5 hexamer, by X-ray crystallography. The five B subunits form a pentameric ring, encircling a helix at the carboxy terminus of the A subunit. The A subunit interacts with the B pentamer via this C-terminal helix and a four-stranded mixed beta-sheet. The fold of the rest of the A subunit is similar to that of the A chain of the plant toxin ricin; both are N-glycosidases. However, the active site in the bacterial holotoxin is blocked by a segment of polypeptide chain. These residues of the A subunit would be released as part of the activation mechanism of the toxin.
Related Citations:
X-ray Crystal Structure of the Shiga Toxin Fraser, M.E., Chernaia, M.M., Kozlov, Y.V., James, M.N. (1996) Protein Toxin Structure, Parker, M W , Ed --: 173
Purification and Crystallization of Shiga Toxin from Shigella dysenteriae Kozlov, Y.V., Chernaia, M.M., Fraser, M.E., James, M.N. (1993) J Mol Biol 232: 704
Organizational Affiliation:
Department of Biochemistry, University of Alberta, Edmonton, Canada.
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