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Diphtheria toxin
Introduction
Diphtheria toxin is an exotoxin secreted by Corynebacterium diphtheriae, the pathogen bacterium that causes diphtheria.
Structure
Structure
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]
Mechanism
Mechanism
It catalyzes the ADP-ribosylation eucaryotic elongation factor-2 (eEF2), inactivating this protein. It does so by ADP-ribosylating the unusual aminoacid diphthamide. In this way, it acts as a RNA translational inhibitor. The exotoxin A of Pseudomonas aeruginosa uses a similar mechanism of action.
Lethal dose
Lethal dose
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]
Clinical use
Clinical use
The drug denileukin diftitox uses diphtheria toxin as an antineoplastic agent.
References
References
- ↑ 1.0 1.1 Murphy JR (1996). Corynebacterium Diphtheriae: Diphtheria Toxin Production In: Baron’s Medical Microbiology (Baron S et al, eds.) (4th ed. 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.
External links
External links
- Diphtheria+Toxin at the US National Library of Medicine Medical Subject Headings (MeSH)