The sequencing of Aspergillus genomes has revealed that the products of a large number of secondary metabolism pathways have not yet been identified. A likely reason is that most secondary metabolism gene clusters are expressed at very low levels under standard laboratory culture conditions. It is, therefore, important to discover conditions or regulatory factors that can induce the expression of these genes. W e report that the deletion of sumO, the gene that encodes the small ubiquitin-like protein SUMO in A. nidulans, caused a dramatic increase in the production of the secondary metabolite asperthecin and a decrease in the synthesis of austinol/dehydroaustinol and sterigmatocystin. The overproduction of asperthecin in the sumO deletion mutant has allowed us, through a series of targeted deletions, to identify the genes required for asperthecin synthesis. The asperthecin biosynthesis genes are clustered and include genes encoding an iterative type I polyketide synthase, a hydrolase, and a monooxygenase. The identification of these genes allows us to propose a biosynthetic pathway for asperthecin. The project was supported by grants PO1GM084077 and RO1GM031837.
Full conference title:
6th International Aspergillus Meeting
- Asperfest 6 (2009)