title: The post-translational trimethylation of diphthamide studied in vitro.
abstract: The amino acid diphthamide is a complex post-translational derivative of histidine that exists in eukaryotic and Archaebacterial elongation factor 2 (EF-2). Diphtheria toxin and Pseudomonas exotoxin A catalyze the transfer of an ADP-ribose residue from NAD to diphthamide, causing the inactivation of EF-2. We have used cytosolic extracts of mutant CHO-K1 cells to study the biosynthesis of diphthamide in vitro. We have identified chromatographically a precursor form of diphthamide that exists in one complementation group of mutant cells and have documented the addition of 3 methyl residues from S-adenosylmethionine to this precursor. We have identified the presence of methyltransferase capable of carrying out this reaction in vitro in cells of 15 diverse eukaryotic species.
authors.affiliation: Department of Microbiology, College of Agriculture and Life Sciences, University of Vermont, Burlington 05405.
authors.forename: J M
authors.initials: JM
authors.lastname: Moehring
authors.forename: T J
authors.initials: TJ
authors.lastname: Moehring
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002460:Cell Line; D003600:Cytosol / Q000378:metabolism; D006639:Histidine / Q000031:analogs & derivatives* / Q000378:metabolism; D008715:Methionine / Q000378:metabolism; D008745:Methylation; D008780:Methyltransferases / Q000378:metabolism*; D020652:Peptide Elongation Factor 2; D010445:Peptide Elongation Factors / Q000235:genetics*; D011499:Protein Processing, Post-Translational; D013045:Species Specificity
chemical_list: D000596:Amino Acids; D020652:Peptide Elongation Factor 2; D010445:Peptide Elongation Factors; D006639:Histidine; C027527:diphthamide; D008715:Methionine; D008780:Methyltransferases; C055181:diphthine methyltransferase