Multistep optimization of a cell-penetrating peptide towards its antimicrobial activity

Biochem J. 2021 Jan 15;478(1):63-78. doi: 10.1042/BCJ20200698.

Abstract

Multidrug resistant (MDR) bacteria have adapted to most clinical antibiotics and are a growing threat to human health. One promising type of candidates for the everlasting demand of new antibiotic compounds constitute antimicrobial peptides (AMPs). These peptides act against different types of microbes by permeabilizing pathogen cell membranes, whereas being harmless to mammalian cells. Contrarily, another class of membrane-active peptides, namely cell-penetrating peptides (CPPs), is known to translocate in eukaryotic cells without substantially affecting the cell membrane. Since CPPs and AMPs share several physicochemical characteristics, we hypothesized if we can rationally direct the activity of a CPP towards antimicrobial activity. Herein, we describe the screening of a synthetic library, based on the CPP sC18, including structure-based design to identify the active residues within a CPP sequence and to discover novel AMPs with high activity. Peptides with increased hydrophobicity were tested against various bacterial strains, and hits were further optimized leading to four generations of peptides, with the last also comprising fluorinated amino acid building blocks. Interestingly, beside strong antibacterial activities, we also detected activity in cancer cells, while non-cancerous cells remained unharmed. The results highlight our new candidates, particularly those from generation 4, as a valuable and promising source for the development of future therapeutics with antibacterial activity and beyond.

Keywords: antibiotics; antimicrobial peptides; cell penetrating peptide; peptides.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / pharmacology*
  • Antimicrobial Cationic Peptides / chemical synthesis
  • Antimicrobial Cationic Peptides / chemistry*
  • Antimicrobial Cationic Peptides / pharmacology
  • Antineoplastic Agents / pharmacology*
  • Bacillus subtilis / drug effects
  • Bacillus subtilis / ultrastructure
  • Bacteria / drug effects*
  • Cell Line, Tumor
  • Cell Membrane / drug effects*
  • Cell Survival / drug effects
  • Cell-Penetrating Peptides / chemical synthesis
  • Cell-Penetrating Peptides / chemistry*
  • Cell-Penetrating Peptides / pharmacology
  • Circular Dichroism
  • Corynebacterium glutamicum / drug effects
  • Corynebacterium glutamicum / ultrastructure
  • Halogenation
  • Hemolysis / drug effects
  • Humans
  • Hydrophobic and Hydrophilic Interactions
  • Inhibitory Concentration 50
  • Microbial Sensitivity Tests
  • Micrococcus luteus / drug effects
  • Microscopy, Electron, Scanning
  • Pseudomonas fluorescens / drug effects
  • Pseudomonas fluorescens / ultrastructure

Substances

  • Anti-Bacterial Agents
  • Antimicrobial Cationic Peptides
  • Antineoplastic Agents
  • Cell-Penetrating Peptides