title: An RNA motif advances transcription by preventing Rho-dependent termination.
abstract: The transcription termination factor Rho associates with most nascent bacterial RNAs as they emerge from RNA polymerase. However, pharmacological inhibition of Rho derepresses only a small fraction of these transcripts. What, then, determines the specificity of Rho-dependent transcription termination? We now report the identification of a Rho-antagonizing RNA element (RARE) that hinders Rho-dependent transcription termination. We establish that RARE traps Rho in an inactive complex but does not prevent Rho binding to its recruitment sites. Although translating ribosomes normally block Rho access to an mRNA, inefficient translation of an open reading frame in the leader region of the Salmonella mgtCBR operon actually enables transcription of its associated coding region by favoring an RNA conformation that sequesters RARE. The discovery of an RNA element that inactivates Rho signifies that the specificity of nucleic-acid binding proteins is defined not only by the sequences that recruit these proteins but also by sequences that antagonize their activity.
authors.affiliation: Howard Hughes Medical Institute, Yale School of Medicine, New Haven, CT 06536; Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, CT 06536;
authors.forename: Anastasia
authors.initials: A
authors.lastname: Sevostyanova
authors.affiliation: Howard Hughes Medical Institute, Yale School of Medicine, New Haven, CT 06536; Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, CT 06536; Microbial Sciences Institute, Yale University, West Haven, CT 06516 eduardo.groisman@yale.edu.
authors.forename: Eduardo A
authors.initials: EA
authors.lastname: Groisman
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D012329:RNA, Bacterial / Q000737:chemistry* / Q000502:physiology; D012234:Rho Factor / Q000502:physiology*; D012475:Salmonella / Q000235:genetics; D013728:Terminator Regions, Genetic; D014158:Transcription, Genetic / Q000502:physiology*
chemical_list: D012329:RNA, Bacterial; D012234:Rho Factor
keywords: MgtC; Rho-dependent termination; Salmonella; antitermination; transcriptional polarity