The host antimicrobial peptide Bac71-35 binds to bacterial ribosomal proteins and inhibits protein synthesis

Chem Biol. 2014 Dec 18;21(12):1639-47. doi: 10.1016/j.chembiol.2014.10.009. Epub 2014 Nov 13.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antimicrobial Cationic Peptides / chemistry
  • Antimicrobial Cationic Peptides / metabolism*
  • Antimicrobial Cationic Peptides / pharmacology*
  • Bacterial Proteins / biosynthesis*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • DNA, Bacterial / metabolism
  • Dose-Response Relationship, Drug
  • Escherichia coli / cytology
  • Escherichia coli / drug effects
  • Proline
  • Protein Binding
  • Protein Biosynthesis / drug effects*
  • Ribosomal Proteins / biosynthesis*
  • Ribosomal Proteins / genetics
  • Ribosomal Proteins / metabolism*
  • Ribosomes / drug effects
  • Ribosomes / genetics
  • Ribosomes / metabolism
  • Transcription, Genetic / drug effects


  • Antimicrobial Cationic Peptides
  • Bacterial Proteins
  • DNA, Bacterial
  • Ribosomal Proteins
  • Proline