C-terminal domain of the RNA chaperone Hfq drives sRNA competition and release of target RNA

Andrew Santiago-Frangos, Kumari Kavita, Daniel J. Schu, Susan Gottesman, Sarah A. Woodson

Research output: Contribution to journalArticlepeer-review

39 Scopus citations


The bacterial Sm protein and RNA chaperone Hfq stabilizes small noncoding RNAs (sRNAs) and facilitates their annealing to mRNA targets involved in stress tolerance and virulence. Although an arginine patch on the Sm core is needed for Hfq's RNA chaperone activity, the function of Hfq's intrinsically disordered C-terminal domain (CTD) has remained unclear. Here, we use stopped flow spectroscopy to show that the CTD of Escherichia coli Hfq is not needed to accelerate RNA base pairing but is required for the release of dsRNA. The Hfq CTD also mediates competition between sRNAs, offering a kinetic advantage to sRNAs that contact both the proximal and distal faces of the Hfq hexamer. The change in sRNA hierarchy caused by deletion of the Hfq CTD in E. coli alters the sRNA accumulation and the kinetics of sRNA regulation in vivo. We propose that the Hfq CTD displaces sRNAs and annealed sRNA·mRNA complexes from the Sm core, enabling Hfq to chaperone sRNA-mRNA interactions and rapidly cycle between competing targets in the cell.

Original languageEnglish (US)
Pages (from-to)E6089-E6096
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number41
StatePublished - Oct 11 2016


  • Chix
  • Intrinsically disordered protein
  • Posttranscriptional regulation
  • RNA chaperone
  • Small noncoding RNA

ASJC Scopus subject areas

  • General


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