Targeting the alternative sigma factor RpoN to combat virulence in Pseudomonas aeruginosa

Sci Rep. 2017 Oct 3;7(1):12615. doi: 10.1038/s41598-017-12667-y.

Abstract

Pseudomonas aeruginosa is a Gram-negative, opportunistic pathogen that infects immunocompromised and cystic fibrosis patients. Treatment is difficult due to antibiotic resistance, and new antimicrobials are needed to treat infections. The alternative sigma factor 54 (σ54, RpoN), regulates many virulence-associated genes. Thus, we evaluated inhibition of virulence in P. aeruginosa by a designed peptide (RpoN molecular roadblock, RpoN*) which binds specifically to RpoN consensus promoters. We expected that RpoN* binding to its consensus promoter sites would repress gene expression and thus virulence by blocking RpoN and/or other transcription factors. RpoN* reduced transcription of approximately 700 genes as determined by microarray analysis, including genes related to virulence. RpoN* expression significantly reduced motility, protease secretion, pyocyanin and pyoverdine production, rhamnolipid production, and biofilm formation. Given the effectiveness of RpoN* in vitro, we explored its effects in a Caenorhabditis elegans-P. aeruginosa infection model. Expression of RpoN* protected C. elegans in a paralytic killing assay, whereas worms succumbed to paralysis and death in its absence. In a slow killing assay, which mimics establishment and proliferation of an infection, C. elegans survival was prolonged when RpoN* was expressed. Thus, blocking RpoN consensus promoter sites is an effective strategy for abrogation of P. aeruginosa virulence.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Caenorhabditis elegans / genetics
  • Caenorhabditis elegans / microbiology
  • Cell Movement / genetics
  • Cell Proliferation / genetics
  • Disease Models, Animal
  • Drug Resistance, Bacterial / genetics
  • Gene Expression Regulation, Bacterial
  • Glycolipids / biosynthesis
  • Glycolipids / genetics
  • Humans
  • Molecular Targeted Therapy
  • Peptides / administration & dosage
  • Peptides / genetics*
  • Protein Binding
  • Pseudomonas Infections / drug therapy*
  • Pseudomonas Infections / genetics
  • Pseudomonas Infections / pathology
  • Pseudomonas aeruginosa / genetics*
  • Pseudomonas aeruginosa / pathogenicity
  • RNA Polymerase Sigma 54 / administration & dosage
  • RNA Polymerase Sigma 54 / antagonists & inhibitors
  • RNA Polymerase Sigma 54 / genetics*
  • Virulence / genetics

Substances

  • Glycolipids
  • Peptides
  • rhamnolipid
  • RNA Polymerase Sigma 54