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Nucleic Acids Res. 2016 Mar 18;44(5):2429-38. doi: 10.1093/nar/gkv1545. Epub 2016 Jan 20.

Structure of the mammalian antimicrobial peptide Bac7(1-16) bound within the exit tunnel of a bacterial ribosome.

Author information

1
Institut Européen de Chimie et Biologie, University of Bordeaux, Pessac 33607, France U1212, Inserm, Bordeaux 33076, France UMR 5320, CNRS, Bordeaux 33076, France.
2
Gene Center and Department for Biochemistry, University of Munich, Munich 81377, Germany.
3
Department of Life Sciences, University of Trieste, Trieste 34127, Italy.
4
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.
5
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.

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.

PMID:
26792896
PMCID:
PMC4797285
DOI:
10.1093/nar/gkv1545
[Indexed for MEDLINE]
Free PMC Article

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