title: In vivo gene regulation in Salmonella spp. by a salicylate-dependent control circuit.
abstract: Systems allowing tightly regulated expression of prokaryotic genes in vivo are important for performing functional studies of bacterial genes in host-pathogen interactions and establishing bacteria-based therapies. We integrated a regulatory control circuit activated by acetyl salicylic acid (ASA) in attenuated Salmonella enterica that carries an expression module with a gene of interest under control of the XylS2-dependent Pm promoter. This resulted in 20-150-fold induction ex vivo. The regulatory circuit was also efficiently induced by ASA when the bacteria resided in eukaryotic cells, both in vitro and in vivo. To validate the circuit, we administered Salmonella spp., carrying an expression module encoding the 5-fluorocytosine-converting enzyme cytosine deaminase in the bacterial chromosome or in a plasmid, to mice with tumors. Induction with ASA before 5-fluorocytosine administration resulted in a significant reduction of tumor growth. These results demonstrate the usefulness of the regulatory control circuit to selectively switch on gene expression during bacterial infection.
authors.affiliation: Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide-Consejo Superior de Investigaciones Científicas, Carretera, Utrera, Km 1, E-41013 Sevilla, Spain.
authors.forename: José Luis
authors.initials: JL
authors.lastname: Royo
authors.forename: Pablo Daniel
authors.initials: PD
authors.lastname: Becker
authors.forename: Eva María
authors.initials: EM
authors.lastname: Camacho
authors.forename: Angel
authors.initials: A
authors.lastname: Cebolla
authors.forename: Claudia
authors.initials: C
authors.lastname: Link
authors.forename: Eduardo
authors.initials: E
authors.lastname: Santero
authors.forename: Carlos Alberto
authors.initials: CA
authors.lastname: Guzmán
mesh_terms: D051229:3-Phosphoshikimate 1-Carboxyvinyltransferase / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001241:Aspirin / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D005437:Flucytosine / Q000378:metabolism; D005472:Fluorouracil / Q000378:metabolism / Q000627:therapeutic use; D015870:Gene Expression / Q000187:drug effects*; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D005818:Genetic Engineering / Q000379:methods; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D007763:Lac Operon / Q000235:genetics; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism / Q000382:microbiology; D051379:Mice; D009369:Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000382:microbiology; D009876:Operon / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D012480:Salmonella Infections / Q000188:drug therapy / Q000382:microbiology; D019779:Salmonella enterica / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D012980:Sodium Salicylate / Q000494:pharmacology; D013154:Spleen / Q000187:drug effects / Q000378:metabolism / Q000382:microbiology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; C063173:NahR protein, Bacteria; D014157:Transcription Factors; D049452:Green Fluorescent Proteins; D005437:Flucytosine; D051229:3-Phosphoshikimate 1-Carboxyvinyltransferase; D001616:beta-Galactosidase; D001241:Aspirin; D005472:Fluorouracil; D012980:Sodium Salicylate