Enzyme-Primed Native Chemical Ligation Produces Autoinducing Cyclopeptides in Clostridia

Angew Chem Int Ed Engl. 2021 May 3;60(19):10670-10679. doi: 10.1002/anie.202016378. Epub 2021 Mar 26.


Clostridia coordinate many important processes such as toxin production, infection, and survival by density-dependent communication (quorum sensing) using autoinducing peptides (AIPs). Although clostridial AIPs have been proposed to be (thio)lactone-containing peptides, their true structures remain elusive. Here, we report the genome-guided discovery of an AIP that controls endospore formation in Ruminiclostridium cellulolyticum. Through a combination of chemical synthesis and chemical complementation assays with a mutant strain, we reveal that the genuine chemical mediator is a homodetic cyclopeptide (cAIP). Kinetic analyses indicate that the mature cAIP is produced via a cryptic thiolactone intermediate that undergoes a rapid S→N acyl shift, in a manner similar to intramolecular native chemical ligation (NCL). Finally, by implementing a chemical probe in a targeted screen, we show that this novel enzyme-primed, intramolecular NCL is a widespread feature of clostridial AIP biosynthesis.

Keywords: Clostridia; RiPP; cyclopeptide; native chemical ligation; quorum sensing.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Clostridium / chemistry*
  • Kinetics
  • Peptide Hydrolases / chemistry
  • Peptide Hydrolases / metabolism*
  • Peptides, Cyclic / biosynthesis*
  • Peptides, Cyclic / chemistry


  • Peptides, Cyclic
  • Peptide Hydrolases