Unlocking the Chemical Diversity of Plant Natural Product Pathways: Dehydrogenases in Alkaloid Biosynthesis

植物、微生物和昆虫产生复杂的小分子，称为“天然产物”。考虑到生物产生这些分子必须消耗的能量，自然产物显然必须赋予生产这些分子的生物一些进化优势。因此，大多数天然产物都具有某种生物活性。就我们的目的而言，这意味着这些代谢物是广泛应用的丰富资源，包括开发药物，杀虫剂，除草剂，生物材料和生物能源。我们对一类被称为生物碱的天然产物特别感兴趣，它是由各种植物和昆虫产生的。一组生物碱，被称为“单萜吲哚生物碱”，包含了大量的生物碱化合物，其中每一种都是由相同的起始物质产生的。众所周知的化合物士的宁（一种毒药）、奎宁（一种抗疟疾药）、喜树碱（抗癌药）和长春花碱（抗癌药）都是单萜吲哚生物碱。然而，为了有效地利用自然提供的化合物，我们必须开发出大规模生产它们的可靠方法。此外，有方法修饰这些化合物的结构将是有价值的，这样我们就可以测试其他衍生物以提高生物活性。这意味着我们需要了解植物用来构建这些分子的生化过程——生物合成。有了这些知识，我们可以重新编程或基因工程植物或微生物，如面包酵母，以过量生产这些有价值的化合物。此外，如果我们确定并了解植物用来合成这些分子的生物催化剂，我们就有可能以新的方式重组植物的生物合成途径，以制造具有潜在改善生物活性的新分子。在这个提议中，我们描述了我们将如何发现如何自然合成一些单萜吲哚生物碱。我们将确定负责几种重要生物碱生物合成的基因。在初步工作中，我们已经确定了其中两个基因。然后，我们将把这些基因放入我们开发的一种面包酵母中。这种菌株将能够从零开始生产生物碱。

Plants, microbes and insects produce complex small molecules, called "natural products". Given the energy that the organism must expend to produce these molecules, natural products clearly must confer some evolutionary advantage on the producing organism. Therefore, most natural products have some type of biological activity. For our purposes, this means that these metabolites are a rich resource for a wide range of applications, including the development of pharmaceuticals, insecticides, herbicides, biomaterials and bioenergy sources. We are especially interested in a class of natural products known as the alkaloids, which are produced by a wide range of plants and insects. One group of alkaloids, called the "monoterpene indole alkaloids" contains a large assortment of alkaloid compounds, where each is produced from the same starting material. The well-known compounds strychnine (a poison), quinine (an anti-malarial), camptothecin (anticancer) and vinblastine (anticancer) are monoterpene indole alkaloids. However, to effectively utilise the compounds that Nature provides, we must develop robust methods for large-scale production of them. Additionally, it would be valuable to have methods to modify the structures of these compounds so we can test additional derivatives for improved biological activity. This means we need to understand the biochemical processes- the biosynthesis- that the plant uses to construct these molecules. With this knowledge, we can reprogram or genetically engineer plants or microbial organisms such as baker's yeast to overproduce these valuable compounds. Moreover, if we identify and understand the biocatalysts that the plant uses to synthesise these molecules, we can potentially recombine plant biosynthetic pathways in new ways to make novel molecules with potentially improved biological activities. In this proposal, we describe how we will discover how nature synthesises some of the monoterpene indole alkaloids. We will identify the genes that are responsible for biosynthesis in several important alkaloids. In preliminary work, we have already identified two of these genes. We will then place these genes into a strain of baker's yeast that we have developed. This strain will then be able to produce the alkaloids from scratch.