Structures and biosynthesis of 12-membered macrocyclic depsipeptides from Streptomyces sp. ML55

Two novel depsipeptides (1-2) were isolated from Streptomyces sp. ML55 together with two known analogues (3-4). Their structures were elucidated using a combination of NMR experiments, as well as detailed MS/MS experiments. The biosynthetic pathway of isolated compounds was dissected by genome sequencing data analysis for a hybrid nonribosomal peptide synthetase (NRPS) and polyketide synthetase (PKS) assembly line.