title: Exotoxin A-eEF2 complex structure indicates ADP ribosylation by ribosome mimicry.
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.
authors.affiliation: Centre for Structural Biology, Department of Molecular Biology, University of Aarhus, Gustav Wieds Vej 10C, DK-8000, Denmark.
authors.forename: René
authors.initials: R
authors.lastname: Jørgensen
authors.forename: A Rod
authors.initials: AR
authors.lastname: Merrill
authors.forename: Susan P
authors.initials: SP
authors.lastname: Yates
authors.forename: Victor E
authors.initials: VE
authors.lastname: Marquez
authors.forename: Adrian L
authors.initials: AL
authors.lastname: Schwan
authors.forename: Thomas
authors.initials: T
authors.lastname: Boesen
authors.forename: Gregers R
authors.initials: GR
authors.lastname: Andersen
mesh_terms: D036002:ADP Ribose Transferases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000244:Adenosine Diphosphate / Q000378:metabolism*; D001427:Bacterial Toxins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D002384:Catalysis; D018360:Crystallography, X-Ray; D005098:Exotoxins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D018716:Molecular Mimicry; D009243:NAD / Q000378:metabolism; D020652:Peptide Elongation Factor 2 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011487:Protein Conformation; D011550:Pseudomonas aeruginosa / Q000737:chemistry; D012266:Ribose / Q000378:metabolism*; D012270:Ribosomes / Q000737:chemistry / Q000378:metabolism*; D012441:Saccharomyces cerevisiae; D037521:Virulence Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000097668:Pseudomonas aeruginosa Exotoxin A
chemical_list: D036002:ADP Ribose Transferases; D000244:Adenosine Diphosphate; D001427:Bacterial Toxins; D005098:Exotoxins; D009243:NAD; D020652:Peptide Elongation Factor 2; D012266:Ribose; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A