Identification of the sigma E subunit of Escherichia coli RNA polymerase: a second alternate sigma factor involved in high-temperature gene expression. Academic Article uri icon


  • The rpoH gene of Escherichia coli encodes sigma 32, the 32-kD sigma-factor responsible for the heat-inducible transcription of the heat shock genes. rpoH is transcribed from at least three promoters. Two of these promoters are recognized by RNA polymerase containing sigma 70, the predominant sigma-factor. We purified the factor responsible for recognizing the third rpoH promoter (rpoH P3) and identified it as RNA polymerase containing a novel sigma-factor with an apparent Mr of 24,000. This new sigma, which we call sigma E, is distinct from the known sigma factors in molecular weight and promoter specificity. sigma E holoenzyme will not recognize the sigma 70- or sigma 32-controlled promoters we tested, but it does transcribe the htrA gene, which is required for viability at temperatures greater than 42 degrees C. The in vivo role of sigma E is not known. The transcripts from the sigma E-controlled rpoH P3 and htrA promoters are most abundant at very high temperature, suggesting the sigma E holoenzyme may transcribe a second set of heat-inducible genes that are involved in growth at high temperature or in thermotolerance.

published proceedings

  • Genes Dev

altmetric score

  • 3

author list (cited authors)

  • Erickson, J. W., & Gross, C. A.

citation count

  • 367

complete list of authors

  • Erickson, JW||Gross, CA

publication date

  • September 1989