Structural and functional basis of C-methylation of coumarin scaffolds by NovO

Sadler, Joanna C. and Chung, Chun-wa H. and Mosley, Julie E. and Burley, Glenn A. and Humphreys, Luke D. (2017) Structural and functional basis of C-methylation of coumarin scaffolds by NovO. ACS Chemical Biology, 12 (2). pp. 374-379. ISSN 1554-8937

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    Abstract

    C-methylation of aromatic small molecules by C-methyltransferases (C-MTs) is an important biological transformation that involves C–C bond formation using S-adenosyl-l-methionine (SAM) as the methyl donor. Here, two advances in the mechanistic understanding of C-methylation of the 8-position of coumarin substrates catalyzed by the C-MT NovO from Streptomyces spheroides are described. First, a crystal structure of NovO reveals the Arg116-Asn117 and His120-Arg121 motifs are essential for coumarin substrate binding. Second, the active-site His120 is responsible for deprotonation of the phenolic 7-hydroxyl group on the coumarin substrate, activating the rate-determining methyl transfer step from SAM. This work expands our mechanistic knowledge of C-MTs, which could be used in the downstream development of engineered biocatalysts for small molecule C-alkylations.