Discovery, Biological Activity, and Biosynthesis of Pinocicolin A, an Antibiotic Isocyanide Metabolite Produced by Penicillium pinophilum

We discovered new natural products pinocicolins A (1) and B (2) from Penicillium pinophilum and determined the stereochemistry of these compounds by degradation and derivatization. Compound 1, containing two isocyanide groups, exhibited bacteriostatic activity against Gram-positive bacteria depending upon its copper-chelating activity. The biosynthesis of compound 1 was reconstructed in Aspergillus nidulans by heterologous expression of multidomain isocyanide synthase-nonribosomal peptide synthetase Pp_crmA and efflux pump Pp_crmE. This is the first report of the heterologous production of a fungal diisocyanide natural product, highlighting the multistep catalysis of CrmA family enzymes.