title: An RNA thermosensor controls expression of virulence genes in Listeria monocytogenes.
abstract: In Listeria monocytogenes, virulence genes are maximally expressed at 37 degrees C, almost silent at 30 degrees C and controlled by PrfA, a transcriptional activator whose expression is thermoregulated. Here, we show that the untranslated mRNA (UTR) preceding prfA, forms a secondary structure, which masks the ribosome binding region. Mutations predicted to destabilize this structure led to virulence gene expression and invasion of mammalian cells at 30 degrees C. Chemical probing, native gel electrophoresis, in vitro translation, and "compensatory" and "increased stability" mutations demonstrated that the UTR switches between a structure active at high temperatures, and another inactive at low temperatures. Strikingly, when the DNA corresponding to the UTR was fused to gfp in E. coli, bacteria became fluorescent at 37 degrees C, but not at 30 degrees C. This mechanism of posttranscriptional thermoregulation may have important applications.
authors.affiliation: Unité des Interactions Bacteries-Cellules, Institut Pasteur, 28, rue du Docteur Roux, 75724 Cedex 15, Paris, France.
authors.forename: Jörgen
authors.initials: J
authors.lastname: Johansson
authors.forename: Pierre
authors.initials: P
authors.lastname: Mandin
authors.forename: Adriana
authors.initials: A
authors.lastname: Renzoni
authors.forename: Claude
authors.initials: C
authors.lastname: Chiaruttini
authors.forename: Mathias
authors.initials: M
authors.lastname: Springer
authors.forename: Pascale
authors.initials: P
authors.lastname: Cossart
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D004926:Escherichia coli / Q000502:physiology; D015964:Gene Expression Regulation, Bacterial; D008089:Listeria monocytogenes / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D009690:Nucleic Acid Conformation; D010454:Peptide Termination Factors; D012323:RNA Processing, Post-Transcriptional; D022661:RNA, Untranslated; D012270:Ribosomes / Q000378:metabolism; D013696:Temperature; D015534:Trans-Activators / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D010454:Peptide Termination Factors; D022661:RNA, Untranslated; D015534:Trans-Activators