Identification of the First Diketomorpholine Biosynthetic Pathway Using FAC-MS Technology
MatthewT. Robey, Rosa Ye, Jin Woo Bok, Kenneth D. Clevenger, Md Nurul Islam, Cynthia Chen, Raveena Gupta, Michael Swyers, Edward Wu, Peng Gao, Paul M. Thomas, Chengcang C. Wu, Nancy P. Keller, Neil L. Kelleher
Index: 10.1021/acschembio.8b00024
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Abstract
Filamentous fungi are prolific producers of secondary metabolites with drug-like properties, and their genome sequences have revealed an untapped wealth of potential therapeutic leads. To better access these secondary metabolites and characterize their biosynthetic gene clusters, we applied a new platform for screening and heterologous expression of intact gene clusters that uses fungal artificial chromosomes and metabolomic scoring (FAC-MS). We leverage FAC-MS technology to identify the biosynthetic machinery responsible for production of acu-dioxomorpholine, a metabolite produced by the fungus, Aspergilllus aculeatus. The acu-dioxomorpholine nonribosomal peptide synthetase features a new type of condensation domain (designated CR) proposed to use a noncanonical arginine active site for ester bond formation. Using stable isotope labeling and MS, we determine that a phenyllactate monomer deriving from phenylalanine is incorporated into the diketomorpholine scaffold. Acu-dioxomorpholine is highly related to orphan inhibitors of P-glycoprotein targets in multidrug-resistant cancers, and identification of the biosynthetic pathway for this compound class enables genome mining for additional derivatives.