Exploring the Biosynthetic Potential of TsrM, a B12‐dependent Radical SAM Methyltransferase Catalyzing Non‐radical Reactions. Issue 31 (20th April 2022)

• Record Type: Journal Article
• Authors: Soualmia, Feryel; Guillot, Alain; Sabat, Nazarii; Brewee, Clémence; Kubiak, Xavier; Haumann, Michael; Guinchard, Xavier; Benjdia, Alhosna; Berteau, Olivier
• Is Part Of: Chemistry. Volume 28:Issue 31(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-04-20
• Subjects: Cobalamin -- radical AdoMet -- radical SAM -- radical S-adenosylmethionine -- RiPP; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.202200627
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: B12 ‐dependent radical SAM enzymes are an emerging enzyme family with approximately 200, 000 proteins. These enzymes have been shown to catalyze chemically challenging reactions such as methyl transfer to sp2 ‐ and sp3 ‐hybridized carbon atoms. However, to date we have little information regarding their complex mechanisms and their biosynthetic potential. Here we show, using X‐ray absorption spectroscopy, mutagenesis and synthetic probes that the vitamin B12 ‐dependent radical SAM enzyme TsrM catalyzes not only C ‐ but also N ‐methyl transfer reactions further expanding its synthetic versatility. We also demonstrate that TsrM has the unique ability to directly transfer a methyl group to the benzyl core of tryptophan, including the least reactive position C4. Collectively, our study supports that TsrM catalyzes non‐radical reactions and establishes the usefulness of radical SAM enzymes for novel biosynthetic schemes including serial alkylation reactions at particularly inert C−H bonds. Abstract : TsrM is a B12 ‐dependent radical SAM enzyme catalyzing methylation reactions from carbon‐atoms to nucleophilic atoms making it a unique and versatile alkylating agent. TsrM is able to directly transfer methyl groups on the less reactive carbon atom of the indole ring and to install several methyl groups on its substrate. TsrM has thus unique properties among radical SAM enzymes by notably catalyzing non‐radical reactions. (SAM: S‐adenosyl‐L‐methionine).