Exotoxin A-eEF2 complex structure indicates ADP ribosylation by ribosome mimicry.
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.
Jørgensen
René
R
Centre for Structural Biology, Department of Molecular Biology, University of Aarhus, Gustav Wieds Vej 10C, DK-8000, Denmark.
Merrill
A Rod
AR
Yates
Susan P
SP
Marquez
Victor E
VE
Schwan
Adrian L
AL
Boesen
Thomas
T
Andersen
Gregers R
GR
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
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