title: Critical role of a conserved transmembrane lysine in substrate recognition by the proton-coupled oligopeptide transporter YjdL.
abstract: Proton-coupled oligopeptide transporters (POTs) utilize an electrochemical proton gradient to accumulate peptides in the cytoplasm. Changing the highly conserved active-site Lys117 in the Escherichia coli POT YjdL to glutamine resulted in loss of ligand affinity as well as inability to distinguish between a dipeptide ligand and the corresponding dipeptide amide. The radically changed pH(Bulk) profiles of Lys117Gln and Lys117Arg mutants indicate an important role of Lys117 in facilitating protonation of the transporter; a notion that is supported by the close proximity of Lys117 to the conserved ExxERFxYY POT motif previously shown to be involved in proton translocation. These results point toward a novel dual role of Lys117 in direct or indirect interaction with both proton and peptide.
authors.affiliation: Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Johanne M
authors.initials: JM
authors.lastname: Jensen
authors.affiliation: Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Nanda G
authors.initials: NG
authors.lastname: Aduri
authors.affiliation: Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Bala K
authors.initials: BK
authors.lastname: Prabhala
authors.affiliation: Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Rasmus
authors.initials: R
authors.lastname: Jahnsen
authors.affiliation: Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Henrik
authors.initials: H
authors.lastname: Franzyk
authors.affiliation: Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark. Electronic address: om@sund.ku.dk.
authors.forename: Osman
authors.initials: O
authors.lastname: Mirza
mesh_terms: D020816:Amino Acid Motifs / Q000235:genetics; D000595:Amino Acid Sequence; D001665:Binding Sites / Q000235:genetics; D001692:Biological Transport / Q000235:genetics; D002462:Cell Membrane / Q000378:metabolism; D017124:Conserved Sequence / Q000235:genetics; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005973:Glutamine / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D008239:Lysine / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D009842:Oligopeptides / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011522:Protons; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
chemical_list: D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D009842:Oligopeptides; D011522:Protons; C544083:YjdL protein, E coli; D005973:Glutamine; D008239:Lysine
keywords: Lysine; POTs; Peptide binding; Proton coupling; pH profiles