Integrating carbon–halogen bond formation into medicinal plant metabolism

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Halogenation, which was once considered a rare occurrence in nature, has now been observed in many natural product biosynthetic pathways1. However, only a small fraction of halogenated compounds have been isolated from terrestrial plants2. Given the impact that halogenation can have on the biological activity of natural products1, we reasoned that the introduction of halides into medicinal plant metabolism would provide the opportunity to rationally bioengineer a broad variety of novel plant products with altered, and perhaps improved, pharmacological properties. Here we report that chlorination biosynthetic machinery from soil bacteria can be successfully introduced into the medicinal plant Catharanthus roseus (Madagascar periwinkle). These prokaryotic halogenases function within the context of the plant cell to generate chlorinated tryptophan, which is then shuttled into monoterpene indole alkaloid metabolism to yield chlorinated alkaloids. A new functional group—a halide—is thereby introduced into the complex metabolism of C. roseus, and is incorporated in a predictable and regioselective manner onto the plant alkaloid products. Medicinal plants, despite their genetic and developmental complexity, therefore seem to be a viable platform for synthetic biology efforts.

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Figure 1: Monoterpene indole alkaloid biosynthesis.
Figure 2: Chlorinated alkaloids in C. roseus hairy root culture.
Figure 3: Extracted LC–MS chromatograms showing the presence of 12-bromo-19,20-dihydroakuammicine in RebF–RebH hairy roots(5c; m/z 403).


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We acknowledge support from the NIH (GM074820) and the American Cancer Society (RSG-07-025-01-CDD). We thank H.-Y. Lee and M. Tjandra for assistance with NMR characterizations and L. Li for high-resolution mass spectroscopy analysis.

Author information

All authors contributed to experimental design and data analysis. X.Q. initiated the project and its design, and performed steady-state kinetics. W.R. developed and implemented the transformation strategy and performed steady-state kinetics and metabolite analysis. All authors contributed to the preparation of the manuscript.

Correspondence to Sarah E. O’Connor.

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The authors declare no competing financial interests.

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Runguphan, W., Qu, X. & O’Connor, S. Integrating carbon–halogen bond formation into medicinal plant metabolism. Nature 468, 461–464 (2010) doi:10.1038/nature09524

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