Ortho-quinone methides (o-QMs) are reactive intermediates in biosynthesis that give rise to a variety of intra- and intermolecular cyclization/addition products in bacteria, fungi, and plants. Herein, we report a new metabolic deviation of an o-QM intermediate in a benzylic dehydrogenation reaction that links the newly described marine bacterial natural products dihydrotetrachlorizine and tetrachlorizine. We discovered these novel dichloropyrrole-containing compounds from actinomycete strain AJS-327 that unexpectedly harbors in its genome a biosynthetic gene cluster (BGC) of striking similarity to that of chlorizidine, another marine alkaloid bearing a different carbon skeleton. Heterologous expression of the homologous flavin-dependent oxidoreductase enzymes Tcz9 and Clz9 revealed their native functions in tetrachlorizine and chlorizidine biosynthesis, respectively, supporting divergent oxidative dehydrogenation and pyrrolizine-forming reactions. Swapping these berberine bridge enzyme-like oxidoreductases, we produced cyclized and dehydrogenated analogs of tetrachlorizine and chlorizidine, including a dearomatized chlorizidine analog that stabilizes an o-QM via conjugation with a 3H-pyrrolizine ring.
Discovery and Biosynthesis of Tetrachlorizine Reveals Enzymatic Benzylic Dehydrogenation via an ortho-Quinone Methide.
Trevor N. Purdy,Min Cheol Kim,Reiko Cullum,W. Fenical,B. Moore
Published 2021 in Journal of the American Chemical Society
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- Publication year
2021
- Venue
Journal of the American Chemical Society
- Publication date
2021-03-03
- Fields of study
Biology, Medicine, Chemistry
- Identifiers
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- Source metadata
Semantic Scholar, PubMed
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