LAUSR

Significance Xylomyrocins are a unique family of nonribosomal peptides (NRPs) from a limited cohort of phytopathogenic fungi. Xylomyrocin biosynthesis utilizes a sugar acid, derived from carbohydrate metabolism, to initiate the assembly of depsipeptides. This unprecedented metabolic interchange extends the precursor structural space available for NRP synthetase–based natural product assembly. The xylomyrocin NRP synthetase further increases the structural diversity of xylomyrocins by leveraging the multiple alcohol functionalities of the polyol to generate macrocyclic ester regioisomers. Some xylomyrocins display promiscuous peptide backbone N-methylation, despite an otherwise collinearly programmed NRP synthetase. Understanding such rare, flexible biosynthetic programs will improve genome mining and sequence-based NRP structure prediction and open new avenues to generate “unnatural” NRPs for crop protection or pharmaceutical drug discovery.