Isoprenoid metabolism in compositae

类异戊二烯代谢提供了一种机制，将普遍存在的前体异戊烯基焦磷酸引导到各种天然产物的合成中。虽然所有生物体都可以产生类异戊二烯作为其初级代谢的一部分，但植物合成第二层类异戊二烯以增强其适应性。已经鉴定了超过50，000种类异戊二烯，并且存在明确的证据表明，一些类异戊二烯在植物生理学、发育以及与其他生物体的相互作用中具有核心重要性。植物类异戊二烯已被人类用作药物、营养品和工业产品，但由于其结构复杂，这些商品的化学合成通常很困难。为了控制植物或其他异源系统中的类异戊二烯代谢，有必要提高对类异戊二烯生物合成的基础知识。我建议在这里研究的生物化学，运输和碳流的倍半萜内酯（SL）的菊科植物，生菜，向日葵和药用植物青蒿（青蒿）属于。将特别强调抗疟疾药物青蒿素（一种SL内过氧化物衍生物）在A. annua。负责SL C11，13-双键还原和内酯环合成的基因将被鉴定和表征，并将使用嵌合细胞色素P450酶分析倍半萜加氧酶中的结构-功能关系。ATP结合盒转运蛋白在倍半萜类物质转运中的潜在参与将在工程酵母系统和植物中进行严格评估。我也将调查碳流在SL的生物合成使用向日葵毛状体作为一个模型系统。在毛状体中，两种不同的细胞类型（光合和非光合）的协调将通过标记的生物摄食测定，原位免疫定位的关键酶，原位RNA杂交，和单细胞型基因组学研究。建议的多方面的分析将阐明SL是如何合成和运输的菊科的毛状体，并将提供一个合理的SL通量工程。

Isoprenoid metabolism provides mechanisms to channel a ubiquitous precursor, isopentenyl pyrophosphate, into the synthesis of a diverse array of natural products. Although all organisms can produce isoprenoids as part of their primary metabolism, plants synthesize a secondary layer of isoprenoids to augment their adaptation fitness. More than 50,000 isoprenoids have been identified, and clear evidence exists that some isoprenoids are of central importance in plant physiology, development, and interactions with other organisms. Plant isoprenoids have been used by humans as pharmaceuticals, nutraceuticals, and industrial products, but the chemical synthesis of these commodities is often difficult due to their structural complexities. To control the isoprenoid metabolism in plants or in other heterologous systems, it is necessary to advance the basic knowledge of isoprenoid biosynthesis. I propose here to study the biochemistry, transport, and carbon-flow of sesquiterpene lactones (SLs) in the plant family Compositae, to which lettuce, sunflower and medicinal plant sweet wormwood (Artemisia annua) belong. Specific emphasis will be given to the biosynthesis of the anti-malarial drug, artemisinin (an SL endoperoxide derivative), in A. annua. The genes responsible for the SL C11,13-double-bond reduction and lactone ring synthesis will be identified and characterized, and the structure-function relationship in the sesquiterpene oxygenase will be analyzed using chimeric cytochrome P450 enzymes. The potential involvement of ATP-Binding Cassette-transporters in sesquiterpenoid transport will be critically evaluated in an engineered yeast system and plants. I will also investigate carbon-flow in the biosynthesis of SLs using sunflower trichomes as a model system. In the trichomes, the coordination of two distinct cell types (photosynthetic and non-photosynthetic) will be studied by labeled precursor-feeding assays, in situ immunolocalization of key enzymes, in situ RNA hybridization, and single-cell-type genomics. The proposed multi-facet analysis will elucidate how the SLs are synthesized and transported in the trichomes of the Compositae and will provide a rationale for SL flux engineering.