title: Novel biosensors based on flavonoid-responsive transcriptional regulators introduced into Escherichia coli.
abstract: This study describes the construction of two flavonoid biosensors, which can be applied for metabolic engineering of Escherichia coli strains. The biosensors are based on transcriptional regulators combined with autofluorescent proteins. The transcriptional activator FdeR from Herbaspirillum seropedicae SmR1 responds to naringenin, while the repressor QdoR from Bacillus subtilis is inactivated by quercetin and kaempferol. Both biosensors showed over a 7-fold increase of the fluorescent signal after addition of their specific effectors, and a linear correlation between the fluorescence intensity and externally added flavonoid concentration. The QdoR-biosensor was successfully applied for detection of kaempferol production in vivo at the single cell level by fluorescence-activated cell sorting. Furthermore, the amount of kaempferol produced highly correlated with the specific fluorescence of E. coli cells containing a flavonol synthase from Arabidopsis thaliana (fls1). We expect the designed biosensors to be applied for isolation of genes involved in flavonoid biosynthetic pathways.
authors.affiliation: Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kogle Alle 6, 2970 Hørsholm, Denmark.
authors.forename: Solvej
authors.initials: S
authors.lastname: Siedler
authors.affiliation: Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kogle Alle 6, 2970 Hørsholm, Denmark.
authors.forename: Steen G
authors.initials: SG
authors.lastname: Stahlhut
authors.affiliation: Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kogle Alle 6, 2970 Hørsholm, Denmark.
authors.forename: Sailesh
authors.initials: S
authors.lastname: Malla
authors.affiliation: Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kogle Alle 6, 2970 Hørsholm, Denmark. Electronic address: jmau@biosustain.dtu.dk.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Maury
authors.affiliation: Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kogle Alle 6, 2970 Hørsholm, Denmark.
authors.forename: Ana Rute
authors.initials: AR
authors.lastname: Neves
mesh_terms: D001412:Bacillus subtilis; D015374:Biosensing Techniques; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005419:Flavonoids / Q000032:analysis* / Q000096:biosynthesis / Q000235:genetics; D042803:Herbaspirillum / Q000235:genetics*; D010088:Oxidoreductases / Q000096:biosynthesis / Q000235:genetics; D010940:Plant Proteins / Q000096:biosynthesis / Q000235:genetics; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics
chemical_list: D005419:Flavonoids; D010940:Plant Proteins; D014157:Transcription Factors; D010088:Oxidoreductases; C085313:flavonol synthase
keywords: Escherichia coli; Flavonoid; Metabolite sensor; Naringenin; Quercetin; Whole-cell biotransformation