Selectivity of the Escherichia coli RNA polymerase E sigma 38 for overlapping promoters and ability to support CRP activation

Nucleic Acids Res. 1995 Mar 11;23(5):819-26. doi: 10.1093/nar/23.5.819.


A series of gal promoter mutants has been used to compare the in vitro selectivities of the two forms of Escherichia coli RNA polymerase, E sigma 38 and E sigma 70. In the absence of the CRP-cAMP complex, E sigma 38 shows a strong preference for the ga/P1 promoter, whereas E sigma 70 preferentially initiates transcription from the ga/P2 promoter. E sigma 38 selectivity is not affected by the nature and position of the upstream sequences or by the phasing between synthetic upstream curved sequences and the -10 regions. In fact, all effects of mutations in the extended -10 region can be accounted for without evoking strong new sequence preferences for E sigma 38. Finally, both E sigma 38 and E sigma 70 initiate transcription from the ga/P1 promoter in the presence of CRP-cAMP complex and support direct cAMP-CRP activation at several CRP-dependent promoters.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / metabolism*
  • Base Sequence
  • Cyclic AMP / metabolism
  • Cyclic AMP Receptor Protein / metabolism*
  • DNA, Bacterial / metabolism
  • Escherichia coli / enzymology*
  • Molecular Sequence Data
  • Oligodeoxyribonucleotides
  • Point Mutation
  • Promoter Regions, Genetic*
  • Sigma Factor / metabolism*
  • Substrate Specificity


  • Bacterial Proteins
  • Cyclic AMP Receptor Protein
  • DNA, Bacterial
  • Oligodeoxyribonucleotides
  • Sigma Factor
  • sigma factor KatF protein, Bacteria
  • Cyclic AMP