Fig. 4

Phenotype of the SCO4804 overproducing strain. a RT-qPCR analysis of the sco4804 transcript level in the MG66 strain (non-induced and induced with 10 µg/ml thiostrepton) compared to the WT-lux (MG03) and TopA-depleted lux (MG04) strains performed for 24 h cultures grown in 79 medium. b The growth curves of the non-induced MG66 strain and MG66 induced with 10 µg/ml thiostrepton (79 medium, Bioscreen C, measurements every 20 min) compared to the WTØ strain (M145_pIJ6902). c Measurement of luminescence of the MG66 strain in the absence or in the presence of the sco4804 inducer (0 and 10 μg/ml of thiostrepton) indicating the changes of topA promoter activity, performed in liquid 79 medium after 24 h of growth and compared to the control strain (WTØ-lux, MG03_pIJ6902) that contains empty pIJ6902 plasmid (and TopA- depleted lux (MGO4) strains. d Luminescence of MG66 indicating the activity of the topA promoter controlling the lux reporter genes after 48 h of growth on solid MS agar plates, without and with the inducer (10 µg/ml thiostrepton), as compared to the control strain (WTØ-lux, MG03_pIJ6902) that contains empty pIJ6902 plasmid (and TopA-depleted lux (MGO4) strain, negative control (the wild-type strain with empty pFLUXH vector (MG01)) and positive control (the wild type strain with pFLUXH_permE (MG02)). e RT-qPCR analysis of the relative transcription of the topA gene in the SCO4804 overproducing strain (MG66) cultured in 79 medium for 24 h and induced with 10 µg/ml thiostrepton for 30 min, 60 min or cultured for 24 h in the presence of the inducer. The data were compared to the non-induced control and WT-lux strain (MG03) grown for 24 h in 79 medium. f RT-qPCR analysis of the relative transcription of the gyrB gene in the SCO4804-overproducing strain (MG66) induced after 24 h of growth with 10 µg/ml thiostrepton for 30 min and 60 min and/or cultured for 24 h in the presence of the inducer. The data were compared to the non-induced control and WT-lux strain (MG03) grown for 24 h in 79 medium