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

Published version
Peer-reviewed

Type

Article

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Authors

Malecka, Ewelina M 
Bassani, Flavia 
Dendooven, Tom 
Sonnleitner, Elisabeth  ORCID logo  https://orcid.org/0000-0002-6961-9536
Rozner, Marlena 

Abstract

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.

Description

Keywords

Bacterial Proteins, Host Factor 1 Protein, Nucleotide Motifs, Protein Biosynthesis, Pseudomonas aeruginosa, RNA Stability, RNA, Messenger, Repressor Proteins

Journal Title

Nucleic Acids Res

Conference Name

Journal ISSN

0305-1048
1362-4962

Volume Title

49

Publisher

Oxford University Press (OUP)
Sponsorship
Wellcome Trust (200873/Z/16/Z)