The 5' end of two redundant sRNAs is involved in the regulation of multiple targets, including their own regulator

Nucleic Acids Res. 2008 Dec;36(21):6781-94. doi: 10.1093/nar/gkn742. Epub 2008 Oct 25.

Abstract

Small RNAs are widespread regulators of gene expression in numerous organisms. This study describes the mode of action of two redundant Escherichia coli sRNAs, OmrA and OmrB, that downregulate the expression of multiple targets, most of which encode outer membrane proteins. Our results show that both sRNAs directly interact with at least two of these target mRNAs, ompT and cirA, in the vicinity of the translation initiation region, consistent with control of these targets being dependent on both Hfq and RNase E. Interestingly, these interactions depend on short stretches of complementarity and involve the conserved 5' end of OmrA/B. A mutation in this region abolishes control of all OmrA/B targets tested thus far, thereby highlighting the crucial role of the OmrA/B 5' end. This allowed us, by looking for mRNA sequences complementary to the OmrA/B 5' end, to identify ompR as an additional direct target of these two sRNAs. Since the OmpR transcriptional regulator activates expression of both omrA and omrB genes, this newly identified control should result in an autoregulatory loop limiting the amount of OmrA/B sRNAs.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • 5' Untranslated Regions
  • Bacterial Outer Membrane Proteins / genetics
  • Bacterial Outer Membrane Proteins / metabolism
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Base Pairing
  • Endoribonucleases / metabolism
  • Escherichia coli / enzymology
  • Escherichia coli / genetics*
  • Escherichia coli / metabolism
  • Escherichia coli Proteins / genetics
  • Escherichia coli Proteins / metabolism
  • Gene Expression Regulation, Bacterial*
  • Peptide Hydrolases / genetics
  • Peptide Hydrolases / metabolism
  • Protein Biosynthesis
  • RNA, Messenger / chemistry
  • RNA, Messenger / metabolism
  • RNA, Untranslated / biosynthesis
  • RNA, Untranslated / chemistry*
  • Receptors, Cell Surface / genetics
  • Receptors, Cell Surface / metabolism
  • Trans-Activators / genetics
  • Trans-Activators / metabolism

Substances

  • 5' Untranslated Regions
  • Bacterial Outer Membrane Proteins
  • Bacterial Proteins
  • Escherichia coli Proteins
  • RNA, Messenger
  • RNA, Untranslated
  • Receptors, Cell Surface
  • Trans-Activators
  • colicin receptor, E coli
  • ompT protein, E coli
  • osmolarity response regulator proteins
  • Endoribonucleases
  • ribonuclease E
  • Peptide Hydrolases