Establishment of the Inducible Tet-On System for the Activation of the Silent Trichosetin Gene Cluster in Fusarium fujikuroi

• Published in: Toxins Vol. 9; no. 4; p. 126
• Main Authors: Janevska, Slavica, Arndt, Birgit, Baumann, Leonie, Apken, Lisa Helene, Mauriz Marques, Lucas Maciel, Humpf, Hans-Ulrich, Tudzynski, Bettina
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 05-04-2017; MDPI
• Subjects: Activation; Aspergillus - genetics; Bacteria; biosynthesis; Cell Survival - drug effects; Coding; Detoxification; Fungal Proteins - genetics; Fungi; Fusarium; Fusarium - genetics; Fusarium - metabolism; Fusarium fujikuroi; Gene expression; Gene Expression Regulation, Fungal; gene regulation; Genes; Hep G2 Cells; Homology; Humans; Metabolites; Methyltransferase; Multigene Family; N-Methyltransferase; Oryza - microbiology; PKS-NRPS; Plant Diseases - microbiology; Plants (botany); Promoter Regions, Genetic; Pyrrolidinones - isolation & purification; Pyrrolidinones - metabolism; Pyrrolidinones - toxicity; secondary metabolism; Tetrahydronaphthalenes - toxicity; Transcription Factors - genetics; Fungi; Fusarium fujikuroi; gene regulation; secondary metabolism; PKS-NRPS; biosynthesis
• ISSN: 2072-6651; 2072-6651
• DOI: 10.3390/toxins9040126

The PKS-NRPS-derived tetramic acid equisetin and its
-desmethyl derivative trichosetin exhibit remarkable biological activities against a variety of organisms, including plants and bacteria, e.g.,
. The equisetin biosynthetic gene cluster was first described in
, a species distantly related to the notorious rice pathogen
. Here we present the activation and characterization of a homologous, but silent, gene cluster in
. Bioinformatic analysis revealed that this cluster does not contain the equisetin
-methyltransferase gene
and consequently, trichosetin was isolated as final product. The adaption of the inducible, tetracycline-dependent Tet-on promoter system from
achieved a controlled overproduction of this toxic metabolite and a functional characterization of each cluster gene in
. Overexpression of one of the two cluster-specific transcription factor (TF) genes,
, led to an activation of the three biosynthetic cluster genes, including the
key gene. In contrast, overexpression of
, encoding a second Zn(II)₂Cys₆ TF, did not activate adjacent cluster genes. Instead,
was induced by the final product trichosetin and was required for expression of the transporter-encoding gene
. TF23 and MFS-T likely act in consort and contribute to detoxification of trichosetin and therefore, self-protection of the producing fungus.