Acquiring novel chemicals by overexpression of a transcription factor DibT in the dibenzodioxocinone biosynthetic cluster in Pestalotiopsis microspora.

Abstract

The endophytic fungus Pestalotiopsis microspora has drawn attention due to its production of dibenzodioxocinones which are a new class of inhibitors of cholesterol ester transfer protein (CETP). Previous studies showed that the pks8 gene cluster is responsible for the biosynthesis of dibenzodioxocinones in P. microspora. Disrupting the gene encoding a transcription factor DibT, which contains a zinc-finger functional domain, led to a significant decrease in the production of dibenzodioxocinones. To further investigate the function of DibT in the expression of pks8 cluster, we constructed dibT-overexpressing strains and found that all genes in the pks8 cluster were upregulated and the yields of dibenzodioxocinones were significantly increased. Moreover, function of DibT was required for the expression of most PKS genes outside of pks8 clusters, i.e., 43 out of 48 defined PKS genes, and boosted pigmentation of the mycelium and conidia. Still, we identified a new dibenzodioxocinone, 1',2'-dimethyl-3'-formyl- 1',2'-dehydropenicillide (6) and a previously known, but conditionally synthesized dibenzodioxocinone, 3'-methoxy-1',2'-dehydropenicillide (4) from the overexpression strains. Our results show that DibT was the key transcription factor in the expression of pks8 cluster and still has a wide effect on the expression of PKS genes in the genome. This work provides information for the regulation of dibenzodioxocinone biosynthesis and may be helpful for the development of new CETP inhibitors.