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Diphtheria toxin
From Wikipedia, the free encyclopedia
Diphtheria toxin is an exotoxin secreted by Corynebacterium diphtheriae, the pathogen bacterium that causes diphtheria.
Diphtheria toxin is a single polypeptide chain of 535 amino acids consisting of two subunits linked by disulfide bridges. Binding to the cell surface of the less stable of these two subunits allows the more stable part of the protein to penetrate the host cell.[1]
It catalyzes the ADP-ribosylation and inactivates the eucaryotic elongation factor-2 (eEF2). It does so by ADP-ribosylating the unusual aminoacid diphthamide. In this way, it acts as a DNA translational inhibitor.
Diphtheria toxin is extraordinarily potent.[1] The lethal dose for humans is about 0.1 μg/kg of pure protein. A massive release of toxin into the body will likely cause lethal necrosis of the heart and liver.[2]
Diphteria toxin was discovered in 1890 by Emil Adolf von Bering.
- ^ a b Murphy JR (1996). Corynebacterium Diphtheriae: Diphtheria Toxin Production In: Baron's Medical Microbiology (Baron S et al, eds.), 4th ed., Univ of Texas Medical Branch. (via NCBI Bookshelf) ISBN 0-9631172-1-1.
- ^ Pappenheimer A (1977). "Diphtheria toxin.". Annu Rev Biochem 46: 69-94. PMID 20040.
Hexosyltransferases: Glucosyltransferases (Glycogen branching enzyme, Glycogen synthase, Glycogen phosphorylase, Phosphorylase/Myophosphorylase) - Glucuronosyltransferase
Pentosyltransferases: Adenine phosphoribosyltransferase - Hypoxanthine-guanine phosphoribosyltransferase - ADP Ribose (Cholera toxin, Diphtheria toxin, Pertussis toxin, Poly ADP ribose polymerase)