Towards plant synthetic biology: elucidating the novel enzymology of iridoid biosynthesis

植物、微生物和昆虫产生复杂的小分子，称为“天然产物”。考虑到生物体必须消耗能量来生产这些分子，天然产物显然必须赋予生产生物体一些进化优势。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，包括药物，杀虫剂，除草剂，生物材料和生物能源的开发。我们特别感兴趣的一类天然产品被称为环烯醚萜，这是由广泛的植物和昆虫。这些分子中的许多具有杀虫活性，其可用于保护植物免受捕食。其他具有药用活性，作为抗癌剂或抗疟疾剂。例如，众所周知的化合物士的宁（一种毒药）和奎宁（一种抗疟疾药）都是从环烯醚萜衍生而来的。环烯醚萜类化合物还可以在促进人类健康方面发挥作用。例如，诺丽果中存在的环烯醚萜被认为有助于这种食物的健康促进特性。然而，为了有效地利用大自然提供的化合物，我们必须开发出大规模生产它们的可靠方法。这意味着我们需要了解植物用来构建这些分子的生物化学过程-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有机体，如面包酵母，以过量生产这些有价值的化合物。此外，如果我们识别并理解植物用于合成这些分子的生物催化剂，我们就可以以新的方式重组植物生物合成途径，从而制造出具有潜在改善生物活性的新型分子。在这个提议中，我们描述了我们将如何发现自然界如何合成环烯醚萜。我们将鉴定环烯醚萜生物合成中负责三个重要步骤的基因。然后，我们将把这三个基因放入面包酵母中，产生一种能产生简单环烯醚萜化合物的酵母菌株。在长期研究中，我们可以向这种酵母菌株中添加额外的环烯醚萜生物合成基因，以产生具有工业应用的更复杂的环烯醚萜化合物。

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 particularly interested in a class of natural products known as the iridoids, which are produced by a wide range of plants and insects. Many of these molecules have insecticidal activity, which can be used to protect plants from predation. Others have medicinal activity, acting as anti-cancer or anti-malarial agents. For example, the well-known compounds strychnine (a poison) and quinine (an anti-malarial) are derived from iridoids. Iridoids may also play a role in promoting human health. For example, the iridoids present in the Noni fruit are believed to contribute to the health-promoting properties of this food. However, to effectively utilise the compounds that Nature provides, we must develop robust methods for large-scale production of them. 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 bio-catalysts 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 the iridoids. We will identify the genes that are responsible for three important steps in iridoid biosynthesis. We will then place those three genes into baker's yeast, generating a strain of yeast that produces a simple iridoid compound. In longer term studies, we can add additional iridoid biosynthesis genes to this yeast strain to generate more complicated iridoid compounds that have industrial applications.