Reconstitution of Iterative Thioamidation in Closthioamide Biosynthesis Reveals Tailoring Strategy for Nonribosomal Peptide Backbones

Angew Chem Int Ed Engl. 2019 Sep 9;58(37):13014-13018. doi: 10.1002/anie.201905992. Epub 2019 Aug 7.


Thioamide-containing nonribosomal peptides (NRPs) are exceedingly rare. Recently the biosynthetic gene cluster for the thioamidated NRP antibiotic closthioamide (CTA) was reported, however, the enzyme responsible for and the timing of thioamide formation remained enigmatic. Here, genome editing, biochemical assays, and mutational studies are used to demonstrate that an Fe-S cluster containing member of the adenine nucleotide α-hydrolase protein superfamily (CtaC) is responsible for sulfur incorporation during CTA biosynthesis. However, unlike all previously characterized members, CtaC functions in a thiotemplated manner. In addition to prompting a revision of the CTA biosynthetic pathway, the reconstitution of CtaC provides the first example of a NRP thioamide synthetase. Finally, CtaC is used as a bioinformatic handle to demonstrate that thioamidated NRP biosynthetic gene clusters are more widespread than previously appreciated.

Keywords: antibiotics; biosynthesis; enzymes; natural products; thioamide.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / chemistry
  • Anti-Bacterial Agents / metabolism*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Biosynthetic Pathways*
  • Clostridiales / chemistry
  • Clostridiales / genetics
  • Clostridiales / metabolism*
  • Genes, Bacterial
  • Multigene Family
  • Peptide Synthases / genetics
  • Peptide Synthases / metabolism
  • Peptides / chemistry
  • Peptides / genetics
  • Peptides / metabolism*
  • Thioamides / chemistry
  • Thioamides / metabolism*


  • Anti-Bacterial Agents
  • Bacterial Proteins
  • Peptides
  • Thioamides
  • closthioamide
  • Peptide Synthases