Chaxapeptin, a Lasso Peptide from Extremotolerant <i>Streptomyces leeuwenhoekii</i> Strain C58 from the Hyperarid Atacama Desert

Lasso peptides are ribosomally synthesized and post-translationally modified peptides (RiPPs) that possess a unique “lariat knot” structural motif. Genome mining-targeted discovery of new natural products from microbes obtained from extreme environments has led to the identification of a gene cluster directing the biosynthesis of a new lasso peptide, designated as chaxapeptin <b>1</b>, in the genome of <i>Streptomyces leeuwenhoekii</i> strain C58 isolated from the Atacama Desert. Subsequently, <b>1</b> was isolated and characterized using high-resolution electrospray ionization mass spectrometry and nuclear magnetic resonance methods. The lasso nature of <b>1</b> was confirmed by calculating its nuclear Overhauser effect restraint-based solution structure. Chaxapeptin <b>1</b> displayed a significant inhibitory activity in a cell invasion assay with human lung cancer cell line A549