Fig. 1.

The Tet-on system for A. niger. Plasmid pVG4.1 comprises one module ensuring constitutive expression of the tetracycline-dependent transactivator (PgpdA::rtTA2S-M2::TcrgA, with the A. nidulans PgpdA promoter and the A. fumigatus crgA terminator), a second module enabling mluc reporter gene expression in an rtTA2-M2-dependent manner (tetO7::Pmin::mluc::TtrpC, with tetO7::Pmin as an rtTA2S-M2-dependent promoter and the A. nidulans trpC terminator), and a third module, pyrG*, necessary for homologous integration of the plasmid at the pyrG locus of A. niger. The control plasmid pVG2.2 is identical to pVG4.1 but lacks the mluc gene. For cloning details and plasmid and fragment sizes, as well as restriction endonuclease sites, see Fig. S1 in the supplemental material.