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 1, in the genome of Streptomyces leeuwenhoekii strain C58 isolated from the Atacama Desert. Subsequently, 1 was isolated and characterized using high-resolution electrospray ionization mass spectrometry and nuclear magnetic resonance methods. The lasso nature of 1 was confirmed by calculating its nuclear Overhauser effect restraint-based solution structure. Chaxapeptin 1 displayed a significant inhibitory activity in a cell invasion assay with human lung cancer cell line A549.