Exotoxin A-eEF2 complex structure indicates ADP ribosylation by ribosome mimicry

Nature. 2005 Aug 18;436(7053):979-84. doi: 10.1038/nature03871.

Abstract

The bacteria causing diphtheria, whooping cough, cholera and other diseases secrete mono-ADP-ribosylating toxins that modify intracellular proteins. Here, we describe four structures of a catalytically active complex between a fragment of Pseudomonas aeruginosa exotoxin A (ETA) and its protein substrate, translation elongation factor 2 (eEF2). The target residue in eEF2, diphthamide (a modified histidine), spans across a cleft and faces the two phosphates and a ribose of the non-hydrolysable NAD+ analogue, betaTAD. This suggests that the diphthamide is involved in triggering NAD+ cleavage and interacting with the proposed oxacarbenium intermediate during the nucleophilic substitution reaction, explaining the requirement of diphthamide for ADP ribosylation. Diphtheria toxin may recognize eEF2 in a manner similar to ETA. Notably, the toxin-bound betaTAD phosphates mimic the phosphate backbone of two nucleotides in a conformational switch of 18S rRNA, thereby achieving universal recognition of eEF2 by ETA.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • ADP Ribose Transferases / chemistry*
  • ADP Ribose Transferases / genetics
  • ADP Ribose Transferases / metabolism*
  • Adenosine Diphosphate / metabolism*
  • Bacterial Toxins / chemistry*
  • Bacterial Toxins / genetics
  • Bacterial Toxins / metabolism*
  • Binding Sites
  • Catalysis
  • Crystallography, X-Ray
  • Exotoxins / chemistry*
  • Exotoxins / genetics
  • Exotoxins / metabolism*
  • Models, Molecular
  • Molecular Mimicry*
  • NAD / metabolism
  • Peptide Elongation Factor 2 / chemistry*
  • Peptide Elongation Factor 2 / genetics
  • Peptide Elongation Factor 2 / metabolism*
  • Protein Conformation
  • Pseudomonas aeruginosa / chemistry
  • Pseudomonas aeruginosa Exotoxin A
  • Ribose / metabolism*
  • Ribosomes / chemistry
  • Ribosomes / metabolism*
  • Saccharomyces cerevisiae
  • Virulence Factors / chemistry*
  • Virulence Factors / genetics
  • Virulence Factors / metabolism*

Substances

  • Bacterial Toxins
  • Exotoxins
  • Peptide Elongation Factor 2
  • Virulence Factors
  • NAD
  • Adenosine Diphosphate
  • Ribose
  • ADP Ribose Transferases

Associated data

  • PDB/1ZM2
  • PDB/1ZM3
  • PDB/1ZM4
  • PDB/1ZM9