The present invention relates to recombinant-DNA-technology, and particularly to genes involved in the control of basic metabolic processes in fungi. The invention specifically provides a mutated form of the native glucose repressor gene cre of filamentous fungi, wherein the mutation is situated in the C-terminal domain, the N-terminal first zinc finger being intact and the C-terminal region including the second zinc finger being mutated so that the viability of a strain carrying said mutated gene is maintained and the glucose repression is relieved.