title: Glutamic acid 141 of the diphtheria toxin receptor (HB-EGF precursor) is critical for toxin binding and toxin sensitivity.
abstract: The transmembrane precursor of the monkey heparin-binding EGF-like growth factor also functions as a diphtheria toxin receptor. The mouse precursor does not bind the toxin. Previously, the most important region for binding the toxin in the monkey precursor was narrowed down to residues 122-148 through the expression of chimeric mouse/monkey precursors and subsequent toxin-sensitivity assays. To define further the toxin binding domain of the monkey precursor, distinct monkey/mouse chimeric precursors were expressed and assayed. The region between monkey residues 136-148 was found to be absolutely necessary for the retention of toxin sensitivity. Within this region, the monkey and mouse precursors differ in only two residues (residues 141 and 147). A toxin-insensitive monkey/mouse chimera that contained monkey residues 1-136 was converted to a toxin-sensitive chimera by the mutation of a single residue (His141 to Glu141). Expression of a mutant monkey precursor in which a single monkey residue (Glu141) was converted to the mouse residue (His141) yielded a cell line that was approximately 100-fold less sensitive to the toxin and the mutant precursor bound the toxin approximately 12-fold less tightly than the wild-type monkey precursor. Taken together, these results indicate that Glu 141 plays a critical role in toxin binding and toxin sensitivity.
authors.affiliation: Department of Microbiology, The University of Texas Southwestern Medical Center, Dallas 75235-9048, USA.
authors.forename: K P
authors.initials: KP
authors.lastname: Hooper
authors.forename: L
authors.initials: L
authors.lastname: Eidels
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D017931:DNA Primers; D004167:Diphtheria Toxin / Q000378:metabolism* / Q000633:toxicity*; D018698:Glutamic Acid; D000882:Haplorhini; D066257:Heparin-binding EGF-like Growth Factor; D006639:Histidine; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D007700:Kinetics; D051379:Mice; D008969:Molecular Sequence Data; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D021382:Protein Sorting Signals; D011956:Receptors, Cell Surface / Q000737:chemistry* / Q000187:drug effects / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
chemical_list: D017931:DNA Primers; D004167:Diphtheria Toxin; C587883:HBEGF protein, human; C587884:Hbegf protein, mouse; D066257:Heparin-binding EGF-like Growth Factor; D036341:Intercellular Signaling Peptides and Proteins; D021382:Protein Sorting Signals; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins; D018698:Glutamic Acid; D006639:Histidine