title: A real-time analysis of QacR-regulated multidrug resistance in Staphylococcus aureus.
abstract: Here we describe the construction and characterization of a biosensing reporter where luxCDABE genes from Photorhabdus luminescens, engineered for expression in Gram-positive organisms, are under the transcriptional control of QacR repressor from Staphylococcus aureus. In non-pathogenic S. aureus model system we analyzed the activity of the regulatory region acting as multidrug-resistance mediator in wild type strains. The use of full-length bacterial luciferase and the measurement of real-time light emission from intact, living cells make the present system suitable to follow the short term activity of different inducers. Among the tested molecules, tetracyclines showed a peculiar behavior by giving very high induction in a fashion seemingly more related to a general stress condition of the culture than to the direct binding and displacement of QacR from its operator. Temperature shocks confirmed that active transcription from qacA promoter is started in response to unspecific conditions where cell growth is strongly inhibited.
authors.affiliation: Department of Biotechnology, University of Turku, Tykistökatu 6, 6th floor, Turku FIN-20520, Finland.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Galluzzi
authors.forename: Pekka
authors.initials: P
authors.lastname: Virtanen
authors.forename: Matti
authors.initials: M
authors.lastname: Karp
mesh_terms: D000891:Anti-Infective Agents, Local / Q000378:metabolism; D001426:Bacterial Proteins; D001548:Benzalkonium Compounds / Q000378:metabolism; D015374:Biosensing Techniques; D024901:Drug Resistance, Multiple, Bacterial / Q000502:physiology*; D005786:Gene Expression Regulation; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D017930:Genes, Reporter; D005818:Genetic Engineering; D008027:Light; D008163:Luminescent Measurements; D020637:Photorhabdus / Q000235:genetics; D010957:Plasmids / Q000235:genetics / Q000378:metabolism; D011500:Protein Synthesis Inhibitors / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D013211:Staphylococcus aureus / Q000187:drug effects / Q000502:physiology*; D013696:Temperature; D013752:Tetracycline / Q000378:metabolism
chemical_list: D000891:Anti-Infective Agents, Local; D001426:Bacterial Proteins; D001548:Benzalkonium Compounds; D011500:Protein Synthesis Inhibitors; C442128:QacR protein, Staphylococcus aureus; D012097:Repressor Proteins; D013752:Tetracycline