Fig. 2 |. Regulation of the sterigmatocystin biosynthetic gene cluster.

The Aspergillus nidulans sterigmatocystin biosynthetic gene cluster (BGC) is one of the most thoroughly studied BGCs at the regulatory level. The pathway-specific regulatory transcription factor, AflR, and its partner, AflS, are induced by specific proteins (for example, RsmA, a basic leucine zipper transcription factor¹⁴⁶) and are epigenetically regulated by the Velvet complex⁶⁶ and chromatin modifiers, including the histone 3 demethylase KdmB⁶³, the histone 4 acetylase EsaA¹⁴⁷, the histone deacetylases RdpA⁶⁵ and SirA¹⁴⁸ and the histone reader SntB¹⁴⁹. Environmental factors such as light and interactions with other microorganisms or insects also affect the induction of the sterigmatocystin BGC. For example, fungus–bacteria interactions induce the cluster through the histone acetyltransferase GcnE, a member of the histone acetyltransferase SAGA–ADA (Spt–Ada–Gcn5–acetyltransferase–ADA) complex⁶⁹, whereas white light can repress expression of some BGC-encoded genes³⁹. A schematic of the sterigmatocystin BGC details the structure and encoded genes. Adapted with permission from reF.¹⁵⁰, Springer Nature Limited.