Standard Article

Small Regulatory RNAs in Bacteria

  1. Nicholas Delihas

Published Online: 15 MAR 2009

DOI: 10.1002/9780470015902.a0000970.pub2



How to Cite

Delihas, N. 2009. Small Regulatory RNAs in Bacteria. eLS. .

Author Information

  1. State University of New York, Stony Brook, New York, USA

Publication History

  1. Published Online: 15 MAR 2009

This is not the most recent version of the article. View current version (3 NOV 2016)


Intergenic regions of bacteria contain small regulatory ribonucleic acid (srRNA) genes whose transcripts control expression of distal genes. These transcripts, referred to here as srRNAs, primarily act at the level of translation where they bind messenger RNAs (mRNAs). srRNAs can inhibit or activate a target mRNA. Base pairing with mRNAs is imperfect and includes looped out and/or bulged nucleotide positions and noncanonical base pairs as well. The RNA chaparone protein Hfq is involved in many RNA/RNA interactions and ribonucleases, RNase E and RNase III, have been implicated in the destabilization of several target mRNAs. Gene transcription can also be controlled by an srRNA via binding to the RNA polymerase–sigma factor complex and blocking a functional site on the enzyme complex. Many srRNA genes are transcriptionally activated by environmental stress factors and have complex promoter and upstream regulatory sites involved in this activation. The control of outer membrane protein synthesis in response to stress is one major function of bacterial srRNAs.

Key Concepts

Properties of small regulatory RNA genes; control of gene expression at the level of translation and transcription by RNA; RNA/RNA interactions; imperfect RNA base pairing and noncanonical base pairs; bacterial cell response to environmental stress conditions; mechanisms of mRNA translational inactivation and degradation; macromolecular responses and phenotypic changes in a cell.


  • small regulatory RNA;
  • gene regulation;
  • RNA/RNA interactions;
  • translation;
  • transcription