Deletion of the epigenetic regulator GcnE in Aspergillus niger FGSC A1279 activates the production of multiple polyketide metabolites

Epigenetic modification is an important regulatory mechanism in the biosynthesis of secondary metabolites in Aspergillus species, which have been considered to be the treasure trove of new bioactive secondary metabolites. In this study, we reported that deletion of the epigenetic regulator gcnE, a histone acetyltransferase in the SAGA/ADA complex, resulted in the production of 12 polyketide secondary metabolites in A. niger FGSC A1279, which was previously not known to produce toxins or secondary metabolites. Chemical workup and structural elucidation by 1D/2D NMR and high resolution electrospray ionization mass (HR-ESIMS) yielded the novel compound nigerpyrone (1) and five known compounds: carbonarone A (2), pestalamide A (3), funalenone (4), aurasperone E (5), and aurasperone A (6). Based on chemical information and the literature, the biosynthetic gene clusters of funalenone (4), aurasperone E (5), and aurasperone A (6) were located on chromosomes of A. niger FGSC A1279. This study found that inactivation of GcnE activated the production of secondary metabolites in A. niger. The biosynthetic pathway for nigerpyrone and its derivatives was identified and characterized via gene knockout and complementation experiments. A biosynthetic model of this group of pyran-based fungal metabolites was proposed.