Translational activation of rpoS mRNA by the non-coding RNA DsrA and Hfq does not require ribosome binding

Branislav Vecerek, Mads Beich-Frandsen, Armin Resch, Udo Bläsi (Korresp. Autor*in)

Veröffentlichungen: Beitrag in FachzeitschriftArtikelPeer Reviewed


At low temperature, translational activation of rpoS mRNA, encoding the stationary phase sigma-factor, {sigma}S, involves the small regulatory RNA (sRNA) DsrA and the RNA chaperone Hfq. The Hfq-mediated DsrA-rpoS interaction relieves an intramolecular secondary structure that impedes ribosome access to the rpoS ribosome binding site. In addition, DsrA/rpoS duplex formation creates an RNase III cleavage site within the duplex. Previous biochemical studies suggested that DsrA and Hfq associate with the 30S ribosomal subunit protein S1, which implied a role for the ribosome in sRNA-mediated post-transcriptional regulation. Here, we show by ribosome profiling that Hfq partitions with the cytoplasmic fraction rather than with 30S subunits. Besides, by employing immunological techniques, no evidence for a physical interaction between Hfq and S1 was obtained. Similarly, in vitro studies did not reveal a direct interaction between DsrA and S1. By employing a ribosome binding deficient rpoS mRNA, and by using the RNase III clevage in the DsrA/rpoS duplex as a diagnostic marker, we provide in vivo evidence that the Hfq-mediated DsrA/rpoS interaction, and consequently the structural changes in rpoS mRNA precede ribosome binding. These data suggest a simple mechanistic model in which translational activation by DsrA provides a translationally competent rpoS mRNA to which 30S subunits can readily bind.
Seiten (von - bis)1284-1293
FachzeitschriftNucleic Acids Research
PublikationsstatusVeröffentlicht - 2010

ÖFOS 2012

  • 106013 Genetik
  • 106023 Molekularbiologie
  • 106022 Mikrobiologie