title: Membrane topology of the Escherichia coli ExbD protein.
abstract: The ExbD protein is involved in the energy-coupled transport of ferric siderophores, vitamin B12, and B-group colicins across the outer membrane of Escherichia coli. In order to study ExbD membrane topology, ExbD-beta-lactamase fusion proteins were constructed. Cells expressing beta-lactamase fusions to residues 53, 57, 70, 76, 78, 80, 92, 121, and 134 of ExbD displayed high levels of ampicillin resistance, whereas fusions to residues 9 and 19 conferred no ampicillin resistance. It is concluded that the only hydrophobic segment of ExbD, encompassing residues 23 to 43, forms a transmembrane domain and that residues 1 to 22 are located in the cytoplasm and residues 44 to 141 are located in the periplasm.
authors.affiliation: Universität Tübingen, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Kampfenkel
authors.forename: V
authors.initials: V
authors.lastname: Braun
mesh_terms: D000667:Ampicillin / Q000494:pharmacology; D001345:Autoradiography; D001426:Bacterial Proteins / Q000378:metabolism*; D001483:Base Sequence; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism; D004269:DNA, Bacterial; D004352:Drug Resistance, Microbial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D010957:Plasmids; D011487:Protein Conformation; D001618:beta-Lactamases / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C060790:exbD protein, E coli; D000667:Ampicillin; D001618:beta-Lactamases