title: Highly frequent single amino acid substitution in mammalian elongation factor 2 (EF-2) results in expression of resistance to EF-2-ADP-ribosylating toxins.
abstract: Toxin-resistant polypeptide chain elongation factor 2 cDNA has been cloned from a mutant hamster cell line with only non-ADP-ribosylatable elongation factor 2. The mutation conferring resistance to diphtheria toxin and Pseudomonas aeruginosa exotoxin A is a G-to-A transition in the first nucleotide of codon 717. Codon 715 encodes a histidine residue that is modified post-translationally to diphthamide, which is the target amino acid for ADP-ribosylation by both toxins. Transfection of mouse L cells with a recombinant elongation factor 2 cDNA differing from the wild-type only by this G-to-A transition confers resistance to P. aeruginosa exotoxin A. The degrees of toxin-resistant protein synthesis of stable transfectants are dependent on the ratio of non-ADP-ribosylated elongation factor 2 to wild-type elongation factor 2, not the amount of non-ADP-ribosylated elongation factor 2. The mutation creates a new Mbo II restriction site in the elongation factor 2 gene. Several independently isolated diphtheria toxin-resistant Chinese hamster ovary cell lines show the same alteration in the Mbo II restriction pattern.
mesh_terms: D036002:ADP Ribose Transferases; D000246:Adenosine Diphosphate Ribose / Q000378:metabolism*; D000818:Animals; D001427:Bacterial Toxins; D002460:Cell Line; D003001:Cloning, Molecular; D006224:Cricetinae; D004247:DNA / Q000032:analysis; D004167:Diphtheria Toxin / Q000494:pharmacology*; D004351:Drug Resistance / Q000235:genetics; D005098:Exotoxins / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects; D006639:Histidine / Q000031:analogs & derivatives / Q000032:analysis / Q000378:metabolism; D020652:Peptide Elongation Factor 2; D010445:Peptide Elongation Factors / Q000032:analysis* / Q000235:genetics; D010957:Plasmids; D012150:Polymorphism, Restriction Fragment Length; D011499:Protein Processing, Post-Translational; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A
chemical_list: D036002:ADP Ribose Transferases; D000246:Adenosine Diphosphate Ribose; D001427:Bacterial Toxins; D004247:DNA; D004167:Diphtheria Toxin; D005098:Exotoxins; D006639:Histidine; D020652:Peptide Elongation Factor 2; D010445:Peptide Elongation Factors; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A; C027527:diphthamide