Analysis of the Streptomyces coelicolor sigE gene reveals the existence of a subfamily of eubacterial RNA polymerase sigma factors involved in the regulation of extracytoplasmic functions

Proc Natl Acad Sci U S A. 1994 Aug 2;91(16):7573-7. doi: 10.1073/pnas.91.16.7573.


sigma E, an RNA polymerase sigma factor of apparent M(r) 28,000, was previously identified by its ability to direct transcription from the P2 promoter of the agarose gene (dagA) of Streptomyces coelicolor. A degenerate oligonucleotide probe, designed from the N-terminal sequence of purified sigma E, was used to isolate the sigma E gene (sigE). The predicted sequence of sigma E shows greatest similarity to sequences of seven other proteins: Myxococcus xanthus CarQ, Pseudomonas aeruginosa AlgU, Pseudomonas syringae HrpL, Escherichia coli sigma E, Alcaligenes eutrophus CnrH, E. coli FecI, and Bacillus subtilis SigX, a protein of unknown function. These eight proteins define a subfamily of eubacterial RNA polymerase factors sufficiently different from other sigma s that, in many cases, they are not identified by standard similarity searching methods. Available information suggests that all of them regulate extracytoplasmic functions and that they function as effector molecules responding to extracytoplasmic stimuli. A. eutrophus CnrH appears to be a plasmid-encoded factor.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins / classification
  • Bacterial Proteins / genetics*
  • Base Sequence
  • Carrier Proteins / genetics
  • Cloning, Molecular
  • DNA-Directed RNA Polymerases / genetics*
  • Gene Expression Regulation, Bacterial
  • Genes, Bacterial / genetics*
  • Glycoside Hydrolases
  • Molecular Sequence Data
  • Promoter Regions, Genetic / genetics
  • Sequence Homology, Amino Acid
  • Sigma Factor / classification
  • Sigma Factor / genetics*
  • Streptomyces / genetics*
  • Transcription Factors*


  • Bacterial Proteins
  • Carrier Proteins
  • Sigma Factor
  • Transcription Factors
  • sporulation-specific sigma factors
  • DNA-Directed RNA Polymerases
  • Glycoside Hydrolases
  • dagA protein, Streptomyces coelicolor

Associated data

  • GENBANK/D00497
  • GENBANK/D13169
  • GENBANK/L29636