RcsB-BglJ activates the Escherichia coli leuO gene, encoding an H-NS antagonist and pleiotropic regulator of virulence determinants

Mol Microbiol. 2012 Mar;83(6):1109-23. doi: 10.1111/j.1365-2958.2012.07993.x. Epub 2012 Feb 14.


The LysR-type transcription factor LeuO is involved in regulation of pathogenicity determinants and stress responses in Enterobacteriaceae, and acts as antagonist of the global repressor H-NS. Expression of the leuO gene is repressed by H-NS, and it is upregulated in stationary phase and under amino acid starvation conditions. Here, we show that the heterodimer of the FixJ/NarL-type transcription regulators RcsB and BglJ strongly activates expression of leuO and that RcsB-BglJ regulates additional loci. Activation of leuO by RcsB-BglJ is independent of the Rcs phosphorelay system. RcsB-BglJ binds to the leuO promoter region and activates one of two leuO promoters mapped in vivo. Moreover, LeuO antagonizes activation of leuO by RcsB-BglJ and acts as negative autoregulator in vivo and in vitro. Further, the H-NS paralogue StpA causes repression of leuO in addition to H-NS. Together, our data suggest a complex arrangement of regulatory elements and they indicate a feedback control mechanism of leuO expression.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Escherichia coli / genetics
  • Escherichia coli / metabolism*
  • Escherichia coli Proteins / antagonists & inhibitors
  • Escherichia coli Proteins / genetics*
  • Escherichia coli Proteins / metabolism*
  • Fimbriae Proteins / antagonists & inhibitors
  • Fimbriae Proteins / genetics
  • Fimbriae Proteins / metabolism*
  • Gene Expression Regulation, Bacterial*
  • Molecular Chaperones / genetics
  • Molecular Chaperones / metabolism
  • Molecular Sequence Data
  • Operon
  • Promoter Regions, Genetic
  • Protein Binding
  • Trans-Activators / genetics
  • Trans-Activators / metabolism*
  • Transcription Factors / genetics*
  • Transcription Factors / metabolism*
  • Transcriptional Activation
  • Virulence Factors / genetics
  • Virulence Factors / metabolism*


  • BglJ protein, E coli
  • DNA-Binding Proteins
  • Escherichia coli Proteins
  • FimG protein, E coli
  • LeuO protein, E coli
  • Molecular Chaperones
  • RcsB protein, E coli
  • StpA protein, E coli
  • Trans-Activators
  • Transcription Factors
  • Virulence Factors
  • Fimbriae Proteins