Adenylation and S-methylation of cysteine by the bifunctional enzyme TioN in thiocoraline biosynthesis

J Am Chem Soc. 2014 Dec 10;136(49):17350-4. doi: 10.1021/ja510489j. Epub 2014 Nov 26.


The antitumor agent thiocoraline is a nonribosomally biosynthesized bisintercalator natural product, which contains in its peptidic backbone two S-methylated l-cysteine residues. S-Methylation occurs very rarely in nature, and is observed extremely rarely in nonribosomal peptide scaffolds. We have proposed that during thiocoraline biosynthesis, TioN, a stand-alone adenylation domain interrupted by the S-adenosyl-l-methionine binding region of a methyltransferase enzyme, is capable of performing two functions: the adenylation and S-methylation of l-cysteine. Herein, by preparation of knockouts of TioN and its MbtH-like protein partner TioT, we confirmed their role in thiocoraline biosynthesis. We also co-expressed recombinant TioN and TioT and biochemically investigated three potential pathways involving activation, methylation, and loading of l-cysteine onto the TioN partner thiolation domain, TioS(T4). The valuable insights gained into the pathway(s) followed for the production of S-Me-l-Cys-S-TioS(T4) will serve as a guide for the development of novel engineered interrupted adenylation enzymes for combinatorial biosynthesis.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Cysteine / chemistry
  • Cysteine / metabolism*
  • Depsipeptides / biosynthesis*
  • Depsipeptides / chemistry
  • Methylation
  • Methyltransferases / chemistry
  • Methyltransferases / metabolism*
  • Molecular Conformation


  • Depsipeptides
  • thiocoraline
  • Methyltransferases
  • Cysteine