title: The C-terminal domain of Escherichia coli Hfq is required for regulation.
abstract: The Escherichia coli RNA chaperone Hfq is involved in riboregulation of target mRNAs by small trans-encoded non-coding (ncRNAs). Previous structural and genetic studies revealed a RNA-binding surface on either site of the Hfq-hexamer, which suggested that one hexamer can bring together two RNAs in a pairwise fashion. The Hfq proteins of different bacteria consist of an evolutionarily conserved core, whereas there is considerable variation at the C-terminus, with the gamma- and beta-proteobacteria possessing the longest C-terminal extension. Using different model systems, we show that a C-terminally truncated variant of Hfq (Hfq(65)), comprising the conserved hexameric core of Hfq, is defective in auto- and riboregulation. Although Hfq(65) retained the capacity to bind ncRNAs, and, as evidenced by fluorescence resonance energy transfer assays, to induce structural changes in the ncRNA DsrA, the truncated variant was unable to accommodate two non-complementary RNA oligonucleotides, and was defective in mRNA binding. These studies indicate that the C-terminal extension of E. coli Hfq constitutes a hitherto unrecognized RNA interaction surface with specificity for mRNAs.
authors.affiliation: Max F. Perutz Laboratories, University of Vienna, Dr. Bohrgasse 9, 1030 Vienna, Austria.
authors.forename: Branislav
authors.initials: B
authors.lastname: Vecerek
authors.forename: Lukas
authors.initials: L
authors.lastname: Rajkowitsch
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Sonnleitner
authors.forename: Renée
authors.initials: R
authors.lastname: Schroeder
authors.forename: Udo
authors.initials: U
authors.lastname: Bläsi
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics; D001665:Binding Sites; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D035001:Host Factor 1 Protein / Q000737:chemistry* / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000378:metabolism; D058727:RNA, Small Untranslated; D022661:RNA, Untranslated / Q000378:metabolism*; D017384:Sequence Deletion; D012808:Sigma Factor / Q000235:genetics; D019802:Succinic Acid / Q000378:metabolism; D013482:Superoxide Dismutase / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; C405431:DsrA RNA, E coli; D029968:Escherichia coli Proteins; C087373:Hfq protein, E coli; D035001:Host Factor 1 Protein; D012333:RNA, Messenger; D058727:RNA, Small Untranslated; D022661:RNA, Untranslated; D012808:Sigma Factor; C069567:sigma factor KatF protein, Bacteria; D019802:Succinic Acid; C087504:SodB protein, Bacteria; D013482:Superoxide Dismutase