Direct regulation of the pefI-srgC operon encoding the Rck invasin by the quorum-sensing regulator SdiA in Salmonella Typhimurium

Mol Microbiol. 2014 Oct;94(2):254-71. doi: 10.1111/mmi.12738. Epub 2014 Sep 1.

Abstract

One important step for the pathogenesis of Salmonella is its ability to penetrate host cells. Recently, a new entry system involving the outer membrane protein Rck has been characterized. Previous studies have shown that the pefI-srgC locus, which contains rck, was regulated by the temperature and SdiA, the transcriptional regulator of quorum sensing in Salmonella. To decipher the regulation of rck by SdiA, we first confirmed the operon organization of the pefI-srgC locus. Using plasmid-based transcriptional fusions, we showed that only the predicted distal promoter upstream of pefI, PefIP2, displays an SdiA- and acyl-homoserine lactones-dependent activity while the predicted proximal PefIP1 promoter exhibits a very low activity independent on SdiA in our culture conditions. A direct and specific interaction of SdiA with this PefIP2 region was identified using electrophoretic mobility shift assays and surface plasmon resonance studies. We also observed that Rck expression is negatively regulated by the nucleoid-associated H-NS protein at both 25°C and 37°C. This work is the first demonstration of a direct regulation of genes by SdiA in Salmonella and will help further studies designed to identify environmental conditions required for Rck expression and consequently contribute to better characterize the role of this invasin in vivo.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Artificial Gene Fusion
  • Bacterial Proteins / metabolism*
  • DNA, Bacterial / metabolism
  • DNA-Binding Proteins / metabolism
  • Electrophoretic Mobility Shift Assay
  • Gene Expression Profiling
  • Gene Expression Regulation, Bacterial*
  • Gene Order
  • Genes, Bacterial
  • Genes, Reporter
  • Operon*
  • Promoter Regions, Genetic
  • Protein Binding
  • Quorum Sensing
  • Salmonella typhimurium / genetics*
  • Salmonella typhimurium / physiology
  • Surface Plasmon Resonance
  • Temperature
  • Trans-Activators / metabolism*
  • Virulence Factors / biosynthesis*
  • Virulence Factors / genetics

Substances

  • Bacterial Proteins
  • DNA, Bacterial
  • DNA-Binding Proteins
  • H-NS protein, bacteria
  • SdiA protein, bacteria
  • Trans-Activators
  • Virulence Factors