title: Random mutagenesis of the prokaryotic peptide transporter YdgR identifies potential periplasmic gating residues.
abstract: The peptide transporter (PTR) family represents a group of proton-coupled secondary transporters responsible for bulk uptake of amino acids in the form of di- and tripeptides, an essential process employed across species ranging from bacteria to humans. To identify amino acids critical for peptide transport in a prokaryotic PTR member, we have screened a library of mutants of the Escherichia coli peptide transporter YdgR using a high-throughput substrate uptake assay. We have identified 35 single point mutations that result in a full or partial loss of transport activity. Additional analysis, including homology modeling based on the crystal structure of the Shewanella oneidensis peptide transporter PepT(so), identifies Glu(56) and Arg(305) as potential periplasmic gating residues. In addition to providing new insights into transport by members of the PTR family, these mutants provide valuable tools for further study of the mechanism of peptide transport.
authors.affiliation: Research Institute of Molecular Pathology, Dr. Bohr-gasse 7, 1030 Vienna, Austria.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Malle
authors.forename: Hongwen
authors.initials: H
authors.lastname: Zhou
authors.forename: Jana
authors.initials: J
authors.lastname: Neuhold
authors.forename: Bettina
authors.initials: B
authors.lastname: Spitzenberger
authors.forename: Freya
authors.initials: F
authors.lastname: Klepsch
authors.forename: Thomas
authors.initials: T
authors.lastname: Pollak
authors.forename: Oliver
authors.initials: O
authors.lastname: Bergner
authors.forename: Gerhard F
authors.initials: GF
authors.lastname: Ecker
authors.forename: Peggy C
authors.initials: PC
authors.lastname: Stolt-Bergner
mesh_terms: D004926:Escherichia coli / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D033903:Periplasmic Proteins; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000502:physiology; D020592:Shewanella / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D040681:Structural Homology, Protein
chemical_list: D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D033903:Periplasmic Proteins; C518647:dtpA protein, E coli