Adaptation to the host environment: regulation of the SPI1 type III secretion system in Salmonella enterica serovar Typhimurium

Curr Opin Microbiol. 2007 Feb;10(1):24-9. doi: 10.1016/j.mib.2006.12.002. Epub 2007 Jan 5.


Salmonella enterica invades the intestinal epithelium of the host using a type III secretion system encoded on Salmonella pathogenicity island 1 (SPI1). The bacteria integrate environmental signals from a variety of global regulatory systems to precisely induce transcription of SPI1. The regulatory circuit converges on expression of HilA, which directly regulates transcription of the SPI1 apparatus genes. Transcription of hilA is controlled by a complex feed-forward loop. Regulatory signals feed into the system through post-transcriptional and post-translational control of HilD, which in turn activates HilC and RtsA. These three regulators act in concert to control hilA transcription. The system acts as a switch, ensuring that SPI1 is fully on at the appropriate time.

Publication types

  • Research Support, N.I.H., Extramural
  • Review

MeSH terms

  • Adaptation, Physiological
  • Bacterial Proteins / biosynthesis
  • Bacterial Proteins / metabolism*
  • Gene Expression Regulation, Bacterial*
  • Genomic Islands / genetics*
  • Protein Transport
  • Salmonella typhimurium / genetics
  • Salmonella typhimurium / pathogenicity
  • Salmonella typhimurium / physiology*
  • Trans-Activators / biosynthesis
  • Transcription Factors / biosynthesis
  • Transcription, Genetic
  • Virulence / genetics


  • Bacterial Proteins
  • HilA protein, Salmonella
  • HilC protein, Salmonella typhimurium
  • HilD protein, Salmonella typhimurium
  • Trans-Activators
  • Transcription Factors