title: Small RNA-based feedforward loop with AND-gate logic regulates extrachromosomal DNA transfer in Salmonella.
abstract: Horizontal gene transfer via plasmid conjugation is a major driving force in microbial evolution but constitutes a complex process that requires synchronization with the physiological state of the host bacteria. Although several host transcription factors are known to regulate plasmid-borne transfer genes, RNA-based regulatory circuits for host-plasmid communication remain unknown. We describe a posttranscriptional mechanism whereby the Hfq-dependent small RNA, RprA, inhibits transfer of pSLT, the virulence plasmid of Salmonella enterica. RprA employs two separate seed-pairing domains to activate the mRNAs of both the sigma-factor σ(S) and the RicI protein, a previously uncharacterized membrane protein here shown to inhibit conjugation. Transcription of ricI requires σ(S) and, together, RprA and σ(S) orchestrate a coherent feedforward loop with AND-gate logic to tightly control the activation of RicI synthesis. RicI interacts with the conjugation apparatus protein TraV and limits plasmid transfer under membrane-damaging conditions. To our knowledge, this study reports the first small RNA-controlled feedforward loop relying on posttranscriptional activation of two independent targets and an unexpected role of the conserved RprA small RNA in controlling extrachromosomal DNA transfer.
authors: Department of Molecular Biology, Princeton University, Princeton, NJ 08544; Institute for Molecular Infection Biology, University of Würzburg, 97080 Wurzburg, Germany; Department of Biology I, Ludwig-Maximilians-University Munich, 82152 Martinsried, Germany; kai.papenfort@lmu.de joerg.vogel@uni-wuerzburg.de.
authors: Kai
authors: http://orcid.org/0000-0002-5560-9804
authors: K
authors: Papenfort
authors: Departamento de Genética, Facultad de Biología, Universidad de Sevilla, 41080 Seville, Spain.
authors: Elena
authors: E
authors: Espinosa
authors: Departamento de Genética, Facultad de Biología, Universidad de Sevilla, 41080 Seville, Spain.
authors: Josep
authors: J
authors: Casadesús
authors: Institute for Molecular Infection Biology, University of Würzburg, 97080 Wurzburg, Germany; kai.papenfort@lmu.de joerg.vogel@uni-wuerzburg.de.
authors: Jörg
authors: J
authors: Vogel
mesh_terms: D001483:Base Sequence; D002876:Chromosomes, Bacterial; D004269:DNA, Bacterial / Q000235:genetics*; D008969:Molecular Sequence Data; D012329:RNA, Bacterial / Q000235:genetics*; D012475:Salmonella / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid
chemical_list: D004269:DNA, Bacterial; D012329:RNA, Bacterial
keywords: Hfq; RprA; feedforward control; plasmid conjugation; sRNA