The present invention relates to an isolated nucleic acid sequence coding for a PntR transcription factor comprising a nucleotide sequence that is the same as, or is complementary to, or contains any suitable codon substitutions for any of those of SEQ ID NOs: 1, 3 or 5 or comprises a sequence which has at least 60% sequence homology with any of SEQ ID NOs: 1, 3 or 5, as well as corresponding polypeptides, vector systems and host cells comprising the same. In particular, the invention relates to sequences which are obtained from an Aspergillus, Trichoderma or Penicillium cell. The invention further relates to methods for disrupting PntR expression in a cell as well as methods for expression or production of a POI in a host cell in which PntR expression has been disrupted.