作者:Weerawat Runguphan、Xudong Qu、Sarah E. O’Connor
DOI:10.1038/nature09524
日期:2010.11
Medicinal plants produce a variety of structurally complex, pharmaceutically important products, but generate relatively few halogenated compounds. Runguphan et al. remedy that omission by introducing the biosynthetic machinery responsible for chlorination in soil bacteria into the genome of the periwinkle, Catharanthus roseus. The prokaryotic halogenases function within the plant cells to generate chlorinated tryptophan, which is then utilized by the monoterpene indole alkaloid metabolic pathways to yield chlorinated alkaloids. Halogen atoms have been observed in several different classes of natural product, but very few halogenated natural products have been isolated from terrestrial plants. These authors show that biosynthetic machinery responsible for chlorination events in bacteria could be introduced into the medicinal plant Catharanthus roseus. Prokaryotic halogenases function within the plant cells to generate chlorinated tryptophan, which is then used by the monoterpene indole alkaloid metabolic pathways to yield chlorinated alkaloids. 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 groupâa halideâis 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.
药用植物产生多种结构复杂且在药理上重要的产品,但生成的卤素化合物相对较少。Runguphan等人为了解决这一缺陷,将负责土壤细菌氯化的生物合成机械引入了长春花(Catharanthus roseus)的基因组。原核卤素化酶在植物细胞内发挥作用,生成氯化色氨酸,然后通过单萜吲哚生物碱代谢通路产生成氯生物碱。已经在几种不同类别的天然产物中观察到卤素原子,但从陆生植物中分离出的卤素化天然产品非常少。这些作者展示了可以将细菌中负责氯化事件的生物合成机械引入药用植物长春花。原核卤素化酶在植物细胞内发挥作用,生成氯化色氨酸,然后被用于单萜吲哚生物碱的代谢通路,从而获得氯化生物碱。曾经被认为在自然界中很少见的卤化现象,现在已在许多天然产物的生物合成途径中被观察到。然而,从陆生植物中分离的卤素化合物仅占一小部分。考虑到卤化可能对天然产物的生物活性产生的影响,我们认为,将卤素引入药用植物的代谢中,将提供理性生物工程广泛新型植物产品的机会,这些产品可能具有改变甚至改善的药理特性。在这里,我们报告了土壤细菌中的氯化生物合成机械可以成功地引入药用植物长春花(马达加斯加长春花)。这些原核卤素化酶在植物细胞的背景下发挥作用,生成氯化色氨酸,然后转入单萜吲哚生物碱的代谢中,生成氯化生物碱。由此,在C. roseus复杂的代谢中引入了一种新的功能基团——卤素,并以可预测和区域选择性的方式将其结合到植物生物碱产品中。因此,尽管药用植物具有遗传和发育上的复杂性,但似乎仍然是合成生物学努力的可行平台。