Fig. 3

Experimental characterization of xylose inducible promoters in YFP-reporter strains. a Relative ranking of transcript abundancies of selected genes in the genome when mycelia were grown in glucose- (orange) or xylose- (green) containing medium. b Absolute transcript dynamics as log₂-fold changes comparing selected genes after the fungal mycelium was incubated in glucose or xylose supplemented media. c Architecture of YFP-reporter strains to test xylose-inducible promoter sequences. Promoter regions (shown in green) of the cellulose binding protein (P_CBP), β-1,4-xylosidase-like gene (P_XYL) and xylitol-dehydrogenase (P_XDH), respectively, were cloned as transcriptional fusions upstream of a thermostable YFP reporter gene depicted in yellow. The promotors and the reporter gene, were flanked up- and downstream by a transcription terminator sequence (grey). A control strain was generated, which carried a short oligonucleotide spacer upstream of the YFP gene instead of a promoter region. d Experimental workflow of the induction assay. Reporter strains were cultivated in glucose-containing medium to build biomass under repressive conditions, washed and subsequently grown for further 8 h in either fresh glucose-containing medium (glucose) or xylose-containing medium (xylose). Immunoblotting and fluorescence microscopy was performed to monitor YFP expression under the control of the various promoters