Dipthamide is named after the toxin produced by the bacterium Corynebacterium diphtheriae, which targets diphthamide. Besides this toxin, it is also targeted by exotoxin A from Pseudomonas aeruginosa. It is the only target of these toxins.
Structure and biosynthesis
Diphthamide is proposed to be a 2-[3-carboxyamido-3-(trimethylammonio)propyl]histidine. Though this structure has been confirmed by X-ray crystallography, its stereochemistry is uncertain.
Diphthamide is biosynthesized from histidine and S-adenosyl methionine (SAM). The side chain bound to imidazole group and all methyl groups come from SAM. The whole synthesis takes place in three steps:
transfer of 3-amino-3-carboxypropyl group from SAM
transfer of three methyl groups from SAM – synthesis of diphtine
↑Jørgensen R, Merrill AR, Andersen GR (February 2006). "The life and death of translation elongation factor 2". Biochemical Society Transactions. 34 (Pt 1): 1–6. doi:10.1042/BST20060001. PMID16246167.