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Stabilization of Hfq-mediated translational repression by the co-repressor Crc in Pseudomonas aeruginosa.

  • Malecka, Ewelina M1
  • Bassani, Flavia2
  • Dendooven, Tom3
  • Sonnleitner, Elisabeth2
  • Rozner, Marlena2
  • Albanese, Tanino G2
  • Resch, Armin2
  • Luisi, Ben3
  • Woodson, Sarah1
  • Bläsi, Udo2
  • 1 Department of Biophysics, 3400 N. Charles Street, Johns Hopkins University, Baltimore, MD-21218, USA.
  • 2 Department of Microbiology, Immunobiology and Genetics, Max Perutz Labs, University of Vienna, Vienna Biocenter (VBC), Dr. Bohrgasse 9/4, 1030 Vienna, Austria. , (Austria)
  • 3 Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK.
Published Article
Nucleic Acids Research
Oxford University Press
Publication Date
Jun 17, 2021
DOI: 10.1093/nar/gkab510
PMID: 34139006


In Pseudomonas aeruginosa the RNA chaperone Hfq and the catabolite repression control protein (Crc) govern translation of numerous transcripts during carbon catabolite repression. Here, Crc was shown to enhance Hfq-mediated translational repression of several mRNAs. We have developed a single-molecule fluorescence assay to quantitatively assess the cooperation of Hfq and Crc to form a repressive complex on a RNA, encompassing the translation initiation region and the proximal coding sequence of the P. aeruginosa amiE gene. The presence of Crc did not change the amiE RNA-Hfq interaction lifetimes, whereas it changed the equilibrium towards more stable repressive complexes. This observation is in accord with Cryo-EM analyses, which showed an increased compactness of the repressive Hfq/Crc/RNA assemblies. These biophysical studies revealed how Crc protein kinetically stabilizes Hfq/RNA complexes, and how the two proteins together fold a large segment of the mRNA into a more compact translationally repressive structure. In fact, the presence of Crc resulted in stronger translational repression in vitro and in a significantly reduced half-life of the target amiE mRNA in vivo. Although Hfq is well-known to act with small regulatory RNAs, this study shows how Hfq can collaborate with another protein to down-regulate translation of mRNAs that become targets for the degradative machinery. © The Author(s) 2021. Published by Oxford University Press on behalf of Nucleic Acids Research.

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