title: Importance of a Conserved Lys/Arg Residue for Ligand/PDZ Domain Interactions as Examined by Protein Semisynthesis.
abstract: PDZ domains are ubiquitous small protein domains that are mediators of numerous protein-protein interactions, and play a pivotal role in protein trafficking, synaptic transmission, and the assembly of signaling-transduction complexes. In recent years, PDZ domains have emerged as novel and exciting drug targets for diseases (in the brain in particular), so understanding the molecular details of PDZ domain interactions is of fundamental importance. PDZ domains bind to a protein partner at either a C-terminal peptide or internal peptide motifs. Here, we examined the importance of a conserved Lys/Arg residue in the ligand-binding site of the second PDZ domain of PSD-95, by employing a semisynthetic approach. We generated six semisynthetic PDZ domains comprising different proteogenic and nonproteogenic amino acids representing subtle changes of the conserved Lys/Arg residue. These were tested with four peptide interaction partners, representing the two different binding modes. The results highlight the role of a positively charged amino acid in the β1-β2 loop of PDZ domains, and show subtle differences for canonical and noncanonical interaction partners, thus providing additional insight into the mechanism of PDZ/ligand interaction.
authors.affiliation: Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen, Denmark. sorenwp@gmail.com.
authors.forename: Søren W
authors.initials: SW
authors.lastname: Pedersen
authors.affiliation: Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen, Denmark.
authors.forename: Griffin E
authors.initials: GE
authors.lastname: Moran
authors.affiliation: Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen, Denmark.
authors.forename: Vita
authors.initials: V
authors.lastname: Sereikaitė
authors.affiliation: Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen, Denmark.
authors.forename: Linda M
authors.initials: LM
authors.lastname: Haugaard-Kedström
authors.affiliation: Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen, Denmark. kristian.stromgaard@sund.ku.dk.
authors.forename: Kristian
authors.initials: K
authors.lastname: Strømgaard
mesh_terms: D001665:Binding Sites / Q000187:drug effects; D004151:Dipeptides / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008024:Ligands; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000737:chemistry; D008958:Models, Molecular; D054731:PDZ Domains / Q000187:drug effects; D011485:Protein Binding
chemical_list: D004151:Dipeptides; D008024:Ligands; D008565:Membrane Proteins; C104090:arginyllysine
keywords: PDZ domains; amino acids; nonproteogenic amino; protein engineering; protein-protein interactions; semisynthesis