A trans-acting riboswitch controls expression of the virulence regulator PrfA in Listeria monocytogenes

Cell. 2009 Nov 13;139(4):770-9. doi: 10.1016/j.cell.2009.08.046.


Riboswitches are RNA elements acting in cis, controlling expression of their downstream genes through a metabolite-induced alteration of their secondary structure. Here, we demonstrate that two S-adenosylmethionine (SAM) riboswitches, SreA and SreB, can also function in trans and act as noncoding RNAs in Listeria monocytogenes. SreA and SreB control expression of the virulence regulator PrfA by binding to the 5'-untranslated region of its mRNA. Absence of the SAM riboswitches SreA and SreB increases the level of PrfA and virulence gene expression in L. monocytogenes. Thus, the impact of the SAM riboswitches on PrfA expression highlights a link between bacterial virulence and nutrient availability. Together, our results uncover an unexpected role for riboswitches and a distinct class of regulatory noncoding RNAs in bacteria.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 5' Untranslated Regions
  • Bacterial Proteins / genetics*
  • Base Sequence
  • Escherichia coli / genetics
  • Escherichia coli / metabolism
  • Listeria monocytogenes / genetics*
  • Listeria monocytogenes / metabolism
  • Listeria monocytogenes / pathogenicity
  • Molecular Sequence Data
  • Peptide Termination Factors / genetics*
  • Regulatory Sequences, Ribonucleic Acid*
  • Temperature
  • Virulence


  • 5' Untranslated Regions
  • Bacterial Proteins
  • Peptide Termination Factors
  • PrfA protein, Listeria monocytogenes
  • Regulatory Sequences, Ribonucleic Acid