A Flavin-Dependent Decarboxylase–Dehydrogenase–Monooxygenase Assembles the Warhead of α,β-Epoxyketone Proteasome Inhibitors
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- 作者：Daniel Zabala ; Joshua W. Cartwright ; Douglas M. Roberts ; Brian J. C. Law ; Lijiang Song ; Markiyan Samborskyy ; Peter F. Leadlay ; Jason Micklefield ; Gregory L. Challis
- 刊名：Journal of the American Chemical Society
- 出版年：2016
- 出版时间：April 6, 2016
- 年：2016
- 卷：138
- 期：13
- 页码：4342-4345
- 全文大小：327K
- ISSN：1520-5126
文摘
The α,β-epoxyketone proteasome inhibitor TMC-86A was discovered as a previously unreported metabolite of Streptomyces chromofuscus ATCC49982, and the gene cluster responsible for its biosynthesis was identified via genome sequencing. Incorporation experiments with [13C-methyl]an class="smallcaps">l an>-methionine implicated an α-dimethyl-β-keto acid intermediate in the biosynthesis of TMC-86A. Incubation of the chemically synthesized α-dimethyl-β-keto acid with a purified recombinant flavin-dependent enzyme that is conserved in all known pathways for epoxyketone biosynthesis resulted in formation of the corresponding α-methyl-α,β-epoxyketone. This transformation appears to proceed via an unprecedented decarboxylation–dehydrogenation–monooxygenation cascade. The biosynthesis of the TMC-86A warhead is completed by cytochrome P450-mediated hydroxylation of the α-methyl-α,β-epoxyketone.