The RpoS sigma factor relieves H-NS-mediated transcriptional repression of csgA, the subunit gene of fibronectin-binding curli in Escherichia coli

Mol Microbiol. 1993 Feb;7(4):523-36. doi: 10.1111/j.1365-2958.1993.tb01143.x.


Curli encoded by the curlin subunit gene, csgA, are fibronectin- and laminin-binding fibres expressed by many natural Escherichia coli and E. coli K-12 strains in response to low temperature, low osmolarity and stationary-phase growth conditions. Curli expression is dependent on RpoS, a sigma factor that controls many stationary phase-inducible genes. Many commonly used K-12 strains carry an amber mutation in rpoS. Strains able to form curli carry an amber suppressor whereas curli-negative E. coli K-12 strains, in general, are sup0. Introduction of SupD, SupE, or supF suppressors into sup0 strains resulted in expression of temperature-regulated curli. In curli-deficient, RpoS- E. coli K-12 strains, csgA is transcriptionally activated by mutations in hns, which encodes the histone-like protein H-NS. Curli expression, fibronectin binding, and csgA transcription remain temperature- and osmoregulated in such double mutants. Our data suggest that RpoS+ strains, and hence curli-proficient strains of E. coli K-12, are relieved for the transcriptional repression mediated by the H-NS protein upon accumulating RpoS as cells reach stationary phase.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Bacterial Adhesion / genetics
  • Bacterial Outer Membrane Proteins / genetics
  • Bacterial Outer Membrane Proteins / metabolism
  • Bacterial Proteins / genetics*
  • Bacterial Proteins / metabolism
  • Base Sequence
  • Cloning, Molecular
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Escherichia coli / genetics*
  • Escherichia coli / ultrastructure
  • Escherichia coli Infections / genetics
  • Escherichia coli Proteins*
  • Fibronectins / metabolism
  • Gene Expression Regulation, Bacterial*
  • Genetic Variation
  • Laminin / metabolism
  • Molecular Sequence Data
  • Mutagenesis
  • Sigma Factor / metabolism
  • Suppression, Genetic
  • Transcription, Genetic*
  • Water-Electrolyte Balance


  • Bacterial Outer Membrane Proteins
  • Bacterial Proteins
  • DNA-Binding Proteins
  • Escherichia coli Proteins
  • Fibronectins
  • H-NS protein, bacteria
  • Laminin
  • Sigma Factor
  • csgA protein, E coli
  • sigma factor KatF protein, Bacteria
  • Crl protein, Bacteria

Associated data

  • GENBANK/L04979