Discovery and Activation of the Cryptic Cluster from Aspergillus sp. CPCC 400735 for Asperphenalenone Biosynthesis

Postgenomic analysis manifested that filamentous fungi contain numerous natural product biosynthetic gene clusters in their genome, yet most clusters remain cryptic or down-regulated. Herein, we report the successful manipulation of strain Aspergillus sp. CPCC 400735 that enables its genetic engineering via targeted overexpression of pathway-specific transcriptional regulator AspE. The downregulated metabolic pathway encoded by the biosynthetic gene cluster asp was successfully up-activated. Analyses of mutant Ai-OE::aspE extracts led to isolation and characterization of 13 asperphenalenone derivatives, of which 11 of them are new compounds. All of the asperphenalenones exhibited conspicuous anti-influenza A virus effects with IC values of 0.45-2.22 mu M. Additionally, their identification provided insight into biosynthesis of asperphenalenones and might benefit studies of downstream combinatorial biosynthesis. Our study further demonstrates the effective application of targeted overexpressing pathway-specific activator and novel metabolite discovery in microorganisms. These will accelerate the exploitation of the untapped resources and biosynthetic capability in filamentous fungi.

Automated summary

This study successfully manipulated the fungus Aspergillus sp. CPCC 400735 to activate the downregulated metabolic pathway encoded by the biosynthetic gene cluster asp through overexpression of the transcriptional regulator AspE. 13 asperphenalenone derivatives, including 11 new compounds, were isolated and characterized from the mutant extracts, showing significant anti-influenza A virus effects with IC values of 0.45-2.22 μM. The identification of these compounds sheds light on the biosynthesis of asperphenalenones and could benefit downstream combinatorial biosynthesis studies.