Signal Sensing by Sigma 54-dependent Regulators: Derepression as a Control Mechanism

Mol Microbiol. 1996 Feb;19(3):409-16. doi: 10.1046/j.1365-2958.1996.388920.x.


Transcription by RNA polymerase utilizing the alternative sigma factor beta 54 is regulated by a distinct class of positive activators designated the sigma 54-dependent family. The activities of these regulators are themselves modulated in response to a wide variety of environmental signals. Factors that modulate the expression or the activity of the regulatory protein in response to chemical and metabolic changes are ultimately responsible for determining the level of expression of sigma 54-dependent genes and hence the diverse bacterial functions that they encode. Many members of the sigma 54-dependent family are part of two-component sensor-response systems. This MicroReview emphasizes recent data concerning the activities of a distinct subgroup of the sigma 54-dependent regulators that directly sense and respond with transcriptional activation to the presence of small effector molecules in their environment. The functional consequences of effector activation in terms of regulation of the enzymatic (ATPase) activity of these transcriptional activators and interdomain interactions are discussed.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Adenosine Triphosphatases / metabolism
  • Bacterial Proteins / metabolism
  • DNA-Binding Proteins*
  • DNA-Directed RNA Polymerases / chemistry
  • DNA-Directed RNA Polymerases / genetics
  • DNA-Directed RNA Polymerases / metabolism*
  • Gene Expression Regulation, Bacterial*
  • Phosphorylation
  • RNA Polymerase Sigma 54
  • Sigma Factor / chemistry
  • Sigma Factor / genetics
  • Sigma Factor / metabolism*
  • Transcription Factors / chemistry
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • Transcription, Genetic / genetics


  • Bacterial Proteins
  • DNA-Binding Proteins
  • Sigma Factor
  • Transcription Factors
  • DNA-Directed RNA Polymerases
  • RNA Polymerase Sigma 54
  • Adenosine Triphosphatases