title: The Sm-like RNA chaperone Hfq mediates transcription antitermination at Rho-dependent terminators.
abstract: In Escherichia coli, the essential motor protein Rho promotes transcription termination in a tightly controlled manner that is not fully understood. Here, we show that the general post-transcriptional regulatory protein Hfq associates with Rho to regulate Rho function. The Hfq:Rho complex can be further stabilized by RNA bridging both factors in a configuration that inhibits the ATP hydrolysis and duplex unwinding activities of Rho and that mediates transcription antitermination at Rho-dependent terminators in vitro and in vivo. Antitermination at a prototypical terminator (λtR1) requires Hfq binding to an A/U-rich transcript region directly upstream from the terminator. Antitermination is modulated by trans-acting factors (NusG or nucleic acid competitors) that affect Hfq association with Rho or RNA. These data unveil a new Hfq function and a novel transcription regulatory mechanism with potentially important implications for bacterial RNA metabolism, gene silencing, and pathogenicity.
authors.affiliation: Centre de Biophysique Moléculaire, CNRS UPR4301, rue Charles Sadron, Orléans Cedex 2, France.
authors.forename: Makhlouf
authors.initials: M
authors.lastname: Rabhi
authors.forename: Olivier
authors.initials: O
authors.lastname: Espéli
authors.forename: Annie
authors.initials: A
authors.lastname: Schwartz
authors.forename: Bastien
authors.initials: B
authors.lastname: Cayrol
authors.forename: A Rachid
authors.initials: AR
authors.lastname: Rahmouni
authors.forename: Véronique
authors.initials: V
authors.lastname: Arluison
authors.forename: Marc
authors.initials: M
authors.lastname: Boudvillain
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D024202:Electrophoretic Mobility Shift Assay; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D035001:Host Factor 1 Protein / Q000235:genetics* / Q000378:metabolism; D018832:Molecular Chaperones / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D010445:Peptide Elongation Factors / Q000235:genetics / Q000378:metabolism; D020365:RNA Helicases / Q000235:genetics / Q000378:metabolism; D012329:RNA, Bacterial / Q000235:genetics* / Q000378:metabolism; D013728:Terminator Regions, Genetic; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D029968:Escherichia coli Proteins; C087373:Hfq protein, E coli; D035001:Host Factor 1 Protein; D018832:Molecular Chaperones; C070291:NusG protein, E coli; D010445:Peptide Elongation Factors; D012329:RNA, Bacterial; C534627:Rho protein, E coli; D014157:Transcription Factors; D000251:Adenosine Triphosphatases; D020365:RNA Helicases