Genome editing reveals novel thiotemplated assembly of polythioamide antibiotics in anaerobic bacteria.
(2018) Genome editing reveals novel thiotemplated assembly of polythioamide antibiotics in anaerobic bacteria. Angew Chem Int Ed 57(43), 14080-14084.
Closthioamide (CTA) is a unique symmetric nonribosomal peptide with six thioamide moieties that is produced by the Gram-positive obligate anaerobe Ruminiclostridium cellulolyticum. CTA displays potent inhibitory activity against important clinical pathogens, making it a promising drug candidate. Yet, the biosynthesis of this DNA gyrase-targeting antibiotic has remained enigmatic. Using a combination of genome mining, genome editing (targeted group II intron, CRISPR/Cas9), and heterologous expression, we show that CTA biosynthesis involves specialized enzymes for starter unit biosynthesis, amide bond formation, thionation, and dimerization. Surprisingly, CTA biosynthesis involves a novel thiotemplated peptide assembly line that markedly differs from known nonribosomal peptide synthetases. These findings provide the first insights into the biosynthesis of thioamide-containing nonribosomal peptides and offer a starting point for the discovery of related natural products.
doi: 10.1002/anie.201807970 PMID: 30193003