Premium
Hfq‐dependent mRNA unfolding promotes sRNA ‐based inhibition of translation
Author(s) -
Hoekzema Mirthe,
Romilly Cédric,
Holmqvist Erik,
Wagner E Gerhart H
Publication year - 2019
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.15252/embj.2018101199
Subject(s) - biology , translation (biology) , messenger rna , transfer rna , microbiology and biotechnology , rna , biochemistry , gene
Small RNA s post‐transcriptionally regulate many processes in bacteria. Base‐pairing of sRNA s near ribosome‐binding sites in mRNA s inhibits translation, often requiring the RNA chaperone Hfq. In the canonical model, Hfq simultaneously binds sRNA s and mRNA targets to accelerate pairing. Here, we show that the Escherichia coli sRNA s OmrA and OmrB inhibit translation of the diguanylate cyclase DgcM (previously: YdaM), a player in biofilm regulation. In OmrA/B repression of dgcM , Hfq is not required as an RNA interaction platform, but rather unfolds an inhibitory RNA structure that impedes OmrA/B binding. This restructuring involves distal face binding of Hfq and is supported by RNA structure mapping. A corresponding mutant protein cannot support inhibition in vitro and in vivo ; proximal and rim mutations have negligible effects. Strikingly, OmrA/B‐dependent translational inhibition in vitro is restored, in complete absence of Hfq, by a deoxyoligoribonucleotide that base‐pairs to the biochemically mapped Hfq site in dgcM mRNA . We suggest that Hfq‐dependent RNA structure remodeling can promote sRNA access, which represents a mechanism distinct from an interaction platform model.