A third envelope stress signal transduction pathway in Escherichia coli

Mol Microbiol. 2002 Sep;45(6):1599-611. doi: 10.1046/j.1365-2958.2002.03112.x.


Escherichia coli uses overlapping envelope stress responses to adapt to insults to the bacterial envelope that cause protein misfolding. The sigmaE and Cpx envelope stress responses are activated by both common and distinct envelope stresses and respond by increasing the expression of the periplasmic protease DegP as well as target genes unique to each response. The sigmaE pathway is involved in outer membrane protein (OMP) folding quality control whereas the Cpx pathway plays an important role in the assembly of at least one pilus. Previously, we identified the spy gene as a new Cpx regulon member of unknown function. Interestingly, induction of spy expression by severe envelope stresses such as spheroplasting is only partially dependent on an intact Cpx signalling pathway, unlike other Cpx-regulated genes. Here we show that the BaeS sensor kinase and BaeR response regulator also control expression of spy in response to envelope stress. BaeS and BaeR do not affect expression of other known Cpx-regulated genes, however, baeR cpxR double mutants show increased sensitivity to envelope stresses relative to either single mutant alone. We propose that the Bae signal transduction pathway controls a third envelope stress response in E. coli that induces expression of a distinct set of adaptive genes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Outer Membrane Proteins / genetics
  • Bacterial Outer Membrane Proteins / metabolism*
  • Base Sequence
  • DNA Transposable Elements
  • Escherichia coli / genetics
  • Escherichia coli / growth & development
  • Escherichia coli / physiology*
  • Escherichia coli Proteins / genetics
  • Escherichia coli Proteins / metabolism*
  • Gene Expression Regulation, Bacterial*
  • Heat-Shock Response
  • Molecular Sequence Data
  • Mutagenesis, Insertional
  • Periplasmic Proteins / genetics
  • Periplasmic Proteins / metabolism
  • Protein Folding
  • Protein Kinases / genetics
  • Protein Kinases / metabolism*
  • Sigma Factor
  • Signal Transduction*
  • Transcription Factors


  • Bacterial Outer Membrane Proteins
  • DNA Transposable Elements
  • Escherichia coli Proteins
  • Periplasmic Proteins
  • Sigma Factor
  • Spy protein, E coli
  • Transcription Factors
  • sporulation-specific sigma factors
  • Protein Kinases
  • BaeS protein, E coli