Targeted pathway mining reveals novel modified hexapeptides from the demiguisin family

Abstract

Abstract Following the discovery of the piperazic acid (Piz)-containing hexapeptide demiguisin A from a toxic bird-associated Amycolatopsis strain, we aimed to investigate the structural diversity and bioactive potential of this natural product family. Here, we used the dmg biosynthetic gene cluster from Amycolatopsis sp. PS_44_ISF1 as a pathway mining probe to search for alternative demiguisin A producers. A global search identified only one other soil-derived Amycolatopsis sp. NBC_01488, encoding a highly syntenic pathway. Under feather-mimicking conditions, PS_44_ISF1 demonstrated enhanced growth and metabolite production relative to NBC_01488. Despite phylogenomic distance, both strains produced shared metabolites, while NBC_01488 yielded more abundant demiguisins, enabling the isolation of five novel derivatives characterized by two Piz-moieties with different hydroxylation patterns and glycine truncation. Two congeners displayed potent activity against the avian pathogen Mycobacterium intracellulare and moderate activity against Mycobacterium tuberculosis . These findings show that targeted pathway mining guided the expansion of the chemical diversity of Piz-modifications and demiguisin congeners with promising anti- Mycobacterium activity.