An Iterative O‐Methyltransferase Catalyzes 1,11‐Dimethylation of Aspergillus fumigatus Fumaric Acid Amides

Abstract

S-adenosyl-l-methionine (SAM)-dependent methyltransfer is a common biosynthetic strategy to modify natural products. We investigated the previously uncharacterized Aspergillus fumigatus methyltransferase FtpM, which is encoded next to the bimodular fumaric acid amide synthetase FtpA. Structure elucidation of two new A. fumigatus natural products, the 1,11-dimethyl esters of fumaryl-l-tyrosine and fumaryl-l-phenylalanine, together with ftpM gene disruption suggested that FtpM catalyzes iterative methylation. Final evidence that a single enzyme repeatedly acts on fumaric acid amides came from an in vitro biochemical investigation with recombinantly produced FtpM. Size-exclusion chromatography indicated that this methyltransferase is active as a dimer. As ftpA and ftpM homologues are found clustered in other fungi, we expect our work will help to identify and annotate natural product biosynthesis genes in various species.

Carboxyl Methyltransferase Catalysed Formation of Mono‐ and Dimethyl Esters under Aqueous Conditions: Application in Cascade Biocatalysis

“…For the natural substrate 5 we observed only monomethylation, exclusively forming the monoester 6 (Scheme 2). This is in contrast to the previously reported exclusive dimethylation, with no observation of any monoester as an intermediate [23] . In order to confirm the identity of 6 , we synthesised both monoesters 6 and 7 (see Supporting Information) and monoester 6 was identical by HPLC to the biotransformation product.…”

“…This is in contrast to the previously reported exclusive dimethylation, with no observation of any monoester as an intermediate. [23] In order to confirm the identity of 6, we synthesised both monoesters 6 and 7 (see Supporting Information) and monoester 6 was identical by HPLC to the biotransformation product. We then tested both monoesters as enzyme substrates under the same reaction conditions.…”

“…[22] The enzyme known as FtpM is a CMT from Aspergillus fumigatus and was reported to dimethylate fumaryl-Ltyrosine 5 (Scheme 2) and also fumaryl-L-phenylalanine as part of the aromatic fumaric amide biosynthesis pathway. [23] This is a unique enzyme in that it is able to iteratively methylate both carboxylic acid groups of the substrate. Here we show that FtpM can di-and monomethylate a wide range of aromatic dicarboxylic acids, benzoic acids and acyclic acids.…”

Structural, mechanistic and functional insight into gliotoxin bis -thiomethylation in Aspergillus fumigatus

“…Similarly, an iterative O -methyltransferase (FtpM) was recently shown to catalyse 1,11-dimethylation of A. fumigatus fumaric acid amides. No monomethylated derivatives were detectable in the conditions tested [28]. BamL, which dimethylates the N-terminus of PZN, does not release monomethylPZN during the reaction.…”

Iterative l‐Tryptophan Methylation in Psilocybe Evolved by Subdomain Duplication

“…Protein purification : Cultivation of E. coli and gene expression were performed as described . TrpM was purified by metal chelate affinity chromatography on Protino Ni 2+ ‐NTA agarose (Macherey–Nagel).…”