Critical role of a conserved transmembrane lysine in substrate recognition by the proton-coupled oligopeptide transporter YjdL

Johanne M Jensen; Nanda G Aduri; Bala K Prabhala; Rasmus Jahnsen; Henrik Franzyk; Osman Mirza

doi:10.1016/j.biocel.2014.09.016

Critical role of a conserved transmembrane lysine in substrate recognition by the proton-coupled oligopeptide transporter YjdL

Int J Biochem Cell Biol. 2014 Oct:55:311-7. doi: 10.1016/j.biocel.2014.09.016. Epub 2014 Sep 26.

Authors

Johanne M Jensen¹, Nanda G Aduri¹, Bala K Prabhala¹, Rasmus Jahnsen¹, Henrik Franzyk¹, Osman Mirza²

Affiliations

¹ Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
² Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark. Electronic address: [email protected].

PMID: 25261786
DOI: 10.1016/j.biocel.2014.09.016

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.

Keywords: Lysine; POTs; Peptide binding; Proton coupling; pH profiles.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Amino Acid Motifs / genetics
Amino Acid Sequence
Binding Sites / genetics
Biological Transport / genetics
Cell Membrane / metabolism
Conserved Sequence / genetics
Escherichia coli Proteins / chemistry
Escherichia coli Proteins / genetics
Escherichia coli Proteins / metabolism*
Glutamine / chemistry
Glutamine / genetics
Glutamine / metabolism
Kinetics
Lysine / chemistry
Lysine / genetics
Lysine / metabolism*
Membrane Transport Proteins / chemistry
Membrane Transport Proteins / genetics
Membrane Transport Proteins / metabolism*
Models, Molecular
Molecular Sequence Data
Mutation, Missense
Oligopeptides / chemistry
Oligopeptides / metabolism*
Protein Binding
Protein Structure, Tertiary
Protons*
Sequence Homology, Amino Acid
Substrate Specificity

Substances

Escherichia coli Proteins
Membrane Transport Proteins
Oligopeptides
Protons
YjdL protein, E coli
Glutamine
Lysine