Identification of HilD-regulated genes in Salmonella enterica serovar Typhimurium

J Bacteriol. 2014 Mar;196(5):1094-101. doi: 10.1128/JB.01449-13. Epub 2013 Dec 27.

Abstract

Salmonella enterica serovar Typhimurium (S. Typhimurium) pathogenicity island 1 (SPI-1) encodes a type III secretion system required for invasion of host gut epithelial cells. Expression of SPI-1 virulence genes is controlled by a complex hierarchy of transcription factors encoded within and outside SPI-1. The master regulator of SPI-1, HilA, is itself regulated by three homologous transcription factors, HilD, HilC, and RtsA. HilD activates transcription of hilA and other target genes in response to environmental conditions associated with the intestinal microenvironment of the host. We have mapped the binding of HilD across the S. Typhimurium genome using chromatin immunoprecipitation-sequencing (ChIP-seq). Thus, we have identified 17 regions bound by HilD, including 11 novel targets. The majority of HilD targets are located outside SPI-1. We demonstrate transcription activation of 8 genes by HilD; four of these genes have not been previously described as being regulated by HilD, including lpxR, which encodes a lipid A deacylase important for immune evasion. We also show that HilD-activated genes are frequently activated by HilC and RtsA, indicating extensive overlap of the HilD, HilC, and RtsA regulons.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Gene Expression Regulation, Bacterial / physiology*
  • Molecular Sequence Annotation
  • Protein Binding
  • Salmonella typhimurium / genetics
  • Salmonella typhimurium / metabolism*
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*

Substances

  • Bacterial Proteins
  • HilD protein, Salmonella typhimurium
  • Transcription Factors