title: Structure of the mammalian antimicrobial peptide Bac7(1-16) bound within the exit tunnel of a bacterial ribosome.
abstract: Proline-rich antimicrobial peptides (PrAMPs) produced as part of the innate immune response of animals, insects and plants represent a vast, untapped resource for the treatment of multidrug-resistant bacterial infections. PrAMPs such as oncocin or bactenecin-7 (Bac7) interact with the bacterial ribosome to inhibit translation, but their supposed specificity as inhibitors of bacterial rather than mammalian protein synthesis remains unclear, despite being key to developing drugs with low toxicity. Here, we present crystal structures of the Thermus thermophilus 70S ribosome in complex with the first 16 residues of mammalian Bac7, as well as the insect-derived PrAMPs metalnikowin I and pyrrhocoricin. The structures reveal that the mammalian Bac7 interacts with a similar region of the ribosome as insect-derived PrAMPs. Consistently, Bac7 and the oncocin derivative Onc112 compete effectively with antibiotics, such as erythromycin, which target the ribosomal exit tunnel. Moreover, we demonstrate that Bac7 allows initiation complex formation but prevents entry into the elongation phase of translation, and show that it inhibits translation on both mammalian and bacterial ribosomes, explaining why this peptide needs to be stored as an inactive pro-peptide. These findings highlight the need to consider the specificity of PrAMP derivatives for the bacterial ribosome in future drug development efforts.
authors.affiliation: Institut Européen de Chimie et Biologie, University of Bordeaux, Pessac 33607, France U1212, Inserm, Bordeaux 33076, France UMR 5320, CNRS, Bordeaux 33076, France.
authors.forename: A Carolin
authors.initials: AC
authors.lastname: Seefeldt
authors.affiliation: Gene Center and Department for Biochemistry, University of Munich, Munich 81377, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Graf
authors.affiliation: Institut Européen de Chimie et Biologie, University of Bordeaux, Pessac 33607, France U1212, Inserm, Bordeaux 33076, France UMR 5320, CNRS, Bordeaux 33076, France.
authors.forename: Natacha
authors.initials: N
authors.lastname: Pérébaskine
authors.affiliation: Gene Center and Department for Biochemistry, University of Munich, Munich 81377, Germany.
authors.forename: Fabian
authors.initials: F
authors.lastname: Nguyen
authors.affiliation: Gene Center and Department for Biochemistry, University of Munich, Munich 81377, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Arenz
authors.affiliation: Department of Life Sciences, University of Trieste, Trieste 34127, Italy.
authors.forename: Mario
authors.initials: M
authors.lastname: Mardirossian
authors.affiliation: Department of Life Sciences, University of Trieste, Trieste 34127, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Scocchi
authors.affiliation: Gene Center and Department for Biochemistry, University of Munich, Munich 81377, Germany Center for integrated Protein Science Munich (CiPSM), University of Munich, Munich 81377, Germany wilson@lmb.uni-muenchen.de.
authors.forename: Daniel N
authors.initials: DN
authors.lastname: Wilson
authors.affiliation: Institut Européen de Chimie et Biologie, University of Bordeaux, Pessac 33607, France U1212, Inserm, Bordeaux 33076, France UMR 5320, CNRS, Bordeaux 33076, France axel.innis@inserm.fr.
authors.forename: C Axel
authors.initials: CA
authors.lastname: Innis
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry / Q000494:pharmacology; D001665:Binding Sites; D001667:Binding, Competitive; D002417:Cattle; D018360:Crystallography, X-Ray; D004917:Erythromycin / Q000737:chemistry / Q000494:pharmacology; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D020062:Heteroptera / Q000737:chemistry; D019476:Insect Proteins / Q000737:chemistry / Q000494:pharmacology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010456:Peptides, Cyclic / Q000737:chemistry* / Q000494:pharmacology; D011485:Protein Binding; D014176:Protein Biosynthesis / Q000187:drug effects*; D012333:RNA, Messenger / Q000737:chemistry / Q000378:metabolism; D012343:RNA, Transfer / Q000737:chemistry / Q000378:metabolism; D012270:Ribosomes / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D013045:Species Specificity; D016963:Thermus thermophilus / Q000737:chemistry
chemical_list: D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D019476:Insect Proteins; D010456:Peptides, Cyclic; D012333:RNA, Messenger; C056454:bactenecin; C087710:pyrrhocoricin protein, Pyrrhocoris apterus; D004917:Erythromycin; D012343:RNA, Transfer