Discovery and Biosynthesis of Pepticinnamins G-M Featuring Three Enzymes-Catalyzed Nonproteinogenic Amino Acid Formation

Abstract

Since pepticinnamin E was discovered almost 30 years ago, no other pepticinnamin family of natural products has been reported to date. Here, we report the discovery of pepticinnamins G-I (1-3) from a marine Streptomyces sp. PKU-MA01144 and pepticinnamins J-M (4-7) from several mutants, and these new compounds contain different N-methyl-L-alanine and L-tyrosine residues compared to pepticinnamin E. Genome sequencing, heterologous expression, gene deletion, and reconstitution of enzymatic reaction in vitro identified the biosynthetic gene cluster of 1-7 and first experimentally established the biosynthesis of the nonproteinogenic 2-chloro-3-hydroxy-4-methoxy-L-phenylalanine residue by a biopterin-dependent hydroxylase Pep10, an O-methyltransferase Pep9, and a flavin-dependent halogenase Pepl. The biosynthetic research and heterologous expression system in this study set the stage for pathway engineering for more pepticinnamins generation in the future.