Eubacterial sigma-factors

FEMS Microbiol Rev. 1998 Sep;22(3):127-50. doi: 10.1111/j.1574-6976.1998.tb00364.x.


The initiation of transcription is the most important step for gene regulation in eubacteria. To initiate transcription, RNA polymerase has to associate with a small protein, known as a sigma-factor. The sigma-factor directs RNA polymerase to a specific class of promoter sequences. Most bacterial species synthesize several different sigma-factors that recognize different consensus sequences. This variety in sigma-factors provides bacteria with the opportunity to maintain basal gene expression as well as for regulation of gene expression in response to altered environmental or developmental signals. This review focuses on the function, regulation and distribution of the 14 different classes of sigma-factors that are presently known.

Publication types

  • Review

MeSH terms

  • Bacterial Physiological Phenomena*
  • Cyanobacteria / physiology
  • Flagella / physiology
  • Gram-Positive Bacteria / physiology
  • Heat-Shock Proteins / physiology
  • Phylogeny
  • Promoter Regions, Genetic / genetics
  • Sigma Factor / chemistry
  • Sigma Factor / classification
  • Sigma Factor / physiology*
  • Spores
  • Transcription, Genetic / genetics*


  • Heat-Shock Proteins
  • Sigma Factor