Characterization of yatakemycin gene cluster revealing a radical S-adenosylmethionine dependent methyltransferase and highlighting spirocyclopropane biosynthesis.

Yatakemycin (YTM), an antitumor natural product, represents the most potent member of a class of potent anticancer natural products including CC-1065 and duocarmycins. Herein we describe the biosynthetic gene cluster of YTM, which was identified by genome scanning of Streptomyces sp. TP-A0356. This cluster consists of 31 open reading frames (ORFs) and was localized to a 36 kb DNA segment. Moreover, its involvement in YTM biosynthesis was confirmed by cluster deletion, gene replacement, and complementation. Inactivation of ytkT, which encodes a radical S-adenosylmethionine (SAM) protein, created a mutant strain that failed to produce YTM but accumulated a new metabolite, which was structurally elucidated as a precursor that was related to the formation of the cyclopropane ring. More importantly, biochemical characterization of the radical SAM-dependent enzyme YtkT revealed that it is a novel C-methyltransferase and contributes to an advanced intermediate during formation of the cyclopropane ring through a radical mechanism in the YTM biosynthetic pathway. On the basis of in silico analysis, genetic experiments, structure elucidation of the novel intermediate, and biochemical characterization, a biosynthetic pathway for yatakemycin was proposed, which sets the stage to further investigate the novel enzymatic mechanisms and engineer the biosynthetic machinery for the production of novel analogues.

Citation

Wei Huang, Hui Xu, Yan Li, Feng Zhang, Xin-Ya Chen, Qing-Li He, Yasuhiro Igarashi, Gong-Li Tang. Characterization of yatakemycin gene cluster revealing a radical S-adenosylmethionine dependent methyltransferase and highlighting spirocyclopropane biosynthesis. Journal of the American Chemical Society. 2012 May 30;134(21):8831-40

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PMID: 22612591

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