title: Formation of a gated channel by a ligand-specific transport protein in the bacterial outer membrane.
abstract: The ferric enterobactin receptor (FepA) is a high-affinity ligand-specific transport protein in the outer membrane of Gram-negative bacteria. Deletion of the cell-surface ligand-binding peptides of FepA generated mutant proteins that were incapable of high-affinity uptake but that instead formed nonspecific, passive channels in the outer membrane. Unlike native FepA, these pores acted independently of the accessory protein TonB, which suggests that FepA is a gated porin and that TonB acts as its gatekeeper by facilitating the entry of ligands into the FepA channel. The sequence homology among TonB-dependent proteins suggests that all ligand-specific outer membrane receptors may function by this gated-porin mechanism.
authors.affiliation: Department of Microbiology, Medical College of Wisconsin, Milwaukee 53226.
authors.forename: J M
authors.initials: JM
authors.lastname: Rutz
authors.forename: J
authors.initials: J
authors.lastname: Liu
authors.forename: J A
authors.initials: JA
authors.lastname: Lyons
authors.forename: J
authors.initials: J
authors.lastname: Goranson
authors.forename: S K
authors.initials: SK
authors.lastname: Armstrong
authors.forename: M A
authors.initials: MA
authors.lastname: McIntosh
authors.forename: J B
authors.initials: JB
authors.lastname: Feix
authors.forename: P E
authors.initials: PE
authors.lastname: Klebba
mesh_terms: D000595:Amino Acid Sequence; D000942:Antigens, Bacterial / Q000737:chemistry; D000954:Antigens, Surface / Q000737:chemistry; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D002352:Carrier Proteins / Q000276:immunology / Q000378:metabolism*; D004252:DNA Mutational Analysis; D004758:Enterobactin / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D015640:Ion Channel Gating; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D011956:Receptors, Cell Surface; D013329:Structure-Activity Relationship
chemical_list: D000942:Antigens, Bacterial; D000954:Antigens, Surface; D001425:Bacterial Outer Membrane Proteins; D002352:Carrier Proteins; D011956:Receptors, Cell Surface; C029489:enterobactin receptor; D004758:Enterobactin