title: The host antimicrobial peptide Bac71-35 binds to bacterial ribosomal proteins and inhibits protein synthesis.
abstract: Antimicrobial peptides (AMPs) are molecules from innate immunity with high potential as novel anti-infective agents. Most of them inactivate bacteria through pore formation or membrane barrier disruption, but others cross the membrane without damages and act inside the cells, affecting vital processes. However, little is known about their intracellular bacterial targets. Here we report that Bac71-35, a proline-rich AMP belonging to the cathelicidin family, can reach high concentrations (up to 340 μM) inside the E. coli cytoplasm. The peptide specifically and completely inhibits in vitro translation in the micromolar concentration range. Experiments of incorporation of radioactive precursors in macromolecules with E. coli cells confirmed that Bac71-35 affects specifically protein synthesis. Ribosome coprecipitation and crosslinking assays showed that the peptide interacts with ribosomes, binding to a limited subset of ribosomal proteins. Overall, these results indicate that the killing mechanism of Bac71-35 is based on a specific block of protein synthesis.
authors.affiliation: Department of Life Sciences, University of Trieste, Via Giorgieri 5, Trieste 34127, Italy.
authors.forename: Mario
authors.initials: M
authors.lastname: Mardirossian
authors.affiliation: Institut des Sciences du Végétal UPR 2355 CNRS, 1 avenue de la Terrasse Bât. 23, 91198 Gif-sur-Yvette, France.
authors.forename: Renata
authors.initials: R
authors.lastname: Grzela
authors.affiliation: Institut des Sciences du Végétal UPR 2355 CNRS, 1 avenue de la Terrasse Bât. 23, 91198 Gif-sur-Yvette, France.
authors.forename: Carmela
authors.initials: C
authors.lastname: Giglione
authors.affiliation: Institut des Sciences du Végétal UPR 2355 CNRS, 1 avenue de la Terrasse Bât. 23, 91198 Gif-sur-Yvette, France.
authors.forename: Thierry
authors.initials: T
authors.lastname: Meinnel
authors.affiliation: Department of Life Sciences, University of Trieste, Via Giorgieri 5, Trieste 34127, Italy.
authors.forename: Renato
authors.initials: R
authors.lastname: Gennaro
authors.affiliation: Institut des Sciences du Végétal UPR 2355 CNRS, 1 avenue de la Terrasse Bât. 23, 91198 Gif-sur-Yvette, France.
authors.forename: Peter
authors.initials: P
authors.lastname: Mergaert
authors.affiliation: Department of Life Sciences, University of Trieste, Via Giorgieri 5, Trieste 34127, Italy. Electronic address: mscocchi@units.it.
authors.forename: Marco
authors.initials: M
authors.lastname: Scocchi
mesh_terms: D023181:Antimicrobial Cationic Peptides / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism*; D004269:DNA, Bacterial / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000166:cytology / Q000187:drug effects; D011392:Proline; D011485:Protein Binding; D014176:Protein Biosynthesis / Q000187:drug effects*; D012269:Ribosomal Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism*; D012270:Ribosomes / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D023181:Antimicrobial Cationic Peptides; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D012269:Ribosomal Proteins; D011392:Proline