Discovery of Pyranoviolin A and Its Biosynthetic Gene Cluster inAspergillus violaceofuscus

A new polyketide-non-ribosomal peptide hybrid molecule, pyranoviolin A (1), was discovered from the genome-sequenced fungusAspergillus violaceofuscusCBS 115571 and was characterized to be the first pyranonigrin analog harboring the C-3 methoxy group. Examination of the genome sequence of the fungus identified a putative biosynthetic gene cluster of1, which was designated as thepyvcluster. The gene deletion experiment of the polyketide synthase (PKS)-non-ribosomal peptide synthetase (NRPS) hybrid gene in the cluster confirmed the involvement of thepyvcluster in the pyranoviolin A biosynthesis. Finally, a plausible biosynthetic route leading to1has been proposed based on the bioinformatic analysis. Our study indicates that metabolite analysis of genome-sequenced microorganisms whose metabolites have been largely unexplored facilitates the discovery of new secondary metabolites along with their biosynthetic gene clusters.