Substrate-Controlled Catalysis in the Ether Cross-Link-Forming Radical SAM Enzymes

J Am Chem Soc. 2023 Oct 25;145(42):22945-22953. doi: 10.1021/jacs.3c04355. Epub 2023 Sep 28.

Abstract

Darobactin is a heptapeptide antibiotic featuring an ether cross-link and a C-C cross-link, and both cross-links are installed by a radical S-adenosylmethionine (rSAM) enzyme DarE. How a single DarE enzyme affords the two chemically distinct cross-links remains largely obscure. Herein, by mapping the biosynthetic landscape for darobactin-like RiPP (daropeptide), we identified and characterized two novel daropeptides that lack the C-C cross-link present in darobactin and instead are solely composed of ether cross-links. Phylogenetic and mutagenesis analyses reveal that the daropeptide maturases possess intrinsic multifunctionality, catalyzing not only the formation of ether cross-link but also C-C cross-linking and Ser oxidation. Intriguingly, the different chemical outcomes are controlled by the exact substrate motifs. Our work not only provides a roadmap for the discovery of new daropeptide natural products but also offers insights into the regulatory mechanisms that govern these remarkably versatile ether cross-link-forming rSAM enzymes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Catalysis
  • Ether*
  • Ethers
  • Ethyl Ethers
  • Phylogeny
  • S-Adenosylmethionine* / chemistry

Substances

  • Ether
  • S-Adenosylmethionine
  • darobactin
  • Ethers
  • Ethyl Ethers