title: Hfq, a new chaperoning role: binding to messenger RNA determines access for small RNA regulator.
abstract: The Sm-like protein Hfq is involved in post-transcriptional regulation by small, noncoding RNAs in Escherichia coli that act by base pairing. Hfq stabilises the small RNAs and mediates their interaction with the target mRNA by an as yet unknown mechanism. We show here a novel chaperoning use of Hfq in the regulation by small RNAs. We analysed in vitro and in vivo the role of Hfq in the interaction between the small RNA RyhB and its sodB (iron superoxide dismutase) mRNA target. Hfq bound strongly to sodB mRNA and altered the structure of the mRNA, partially opening a loop. This gives access to a sequence complementary to RyhB and encompassing the translation initiation codon. RyhB binding blocked the translation initiation codon of sodB and triggered the degradation of both RyhB and sodB mRNA. Thus, Hfq is a critical chaperone in vivo and in vitro, changing the folding of the target mRNA to make it subject to the small RNA regulator.
authors.affiliation: Institut Jacques Monod, CNRS-Universités Paris 6 et Paris 7, Paris, France.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Geissmann
authors.forename: Danièle
authors.initials: D
authors.lastname: Touati
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics; D001483:Base Sequence; D001665:Binding Sites; D029968:Escherichia coli Proteins / Q000378:metabolism / Q000502:physiology*; D035001:Host Factor 1 Protein / Q000378:metabolism / Q000502:physiology*; D018832:Molecular Chaperones / Q000378:metabolism / Q000502:physiology*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D020871:RNA Stability; D012329:RNA, Bacterial / Q000737:chemistry / Q000378:metabolism*; D012333:RNA, Messenger / Q000737:chemistry / Q000378:metabolism*; D022661:RNA, Untranslated / Q000737:chemistry / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000096:biosynthesis / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C087373:Hfq protein, E coli; D035001:Host Factor 1 Protein; D018832:Molecular Chaperones; D012329:RNA, Bacterial; D012333:RNA, Messenger; D022661:RNA, Untranslated; C087504:SodB protein, Bacteria; D013482:Superoxide Dismutase