Isoprenoid metabolism in compositae

复合植物中的类异戊二烯代谢

• 批准号: 341655-2007
• 负责人: Ro, DaeKyun
• 金额: $ 3.18万
• 依托单位: University of Calgary
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2011
• 资助国家: 加拿大
• 起止时间: 2011-01-01 至 2012-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=482216
• 关键词: Isoprenoid; metabolism; compositae

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.

类异戊二烯代谢提供了一种机制，将普遍存在的前体焦磷酸异戊烯基转化为多种天然产物的合成。虽然所有生物都可以产生类异戊二烯作为其初级代谢的一部分，但植物合成二级类异戊二烯以增强其适应性。已鉴定的类异戊二烯超过5万种，有明确证据表明，一些类异戊二烯在植物生理、发育和与其他生物的相互作用中起着至关重要的作用。植物类异戊二烯已被人类用作药品、保健品和工业产品，但由于其结构复杂，这些商品的化学合成通常很困难。为了控制类异戊二烯在植物或其他异源系统中的代谢，有必要提高类异戊二烯生物合成的基础知识。本文拟对莴苣、向日葵和药用植物青蒿等菊科植物倍半萜内酯（SLs）的生物化学、转运和碳流进行研究。将特别强调抗疟疾药物青蒿素（一种SL内过氧化物衍生物）在黄花蒿中的生物合成。鉴定和表征SL C11、13-双键还原和内酯环合成的基因，并利用嵌合细胞色素P450酶分析倍半萜加氧酶的结构-功能关系。将在工程酵母系统和植物中对atp结合盒转运体在倍半萜类转运中的潜在参与进行严格评估。我还将使用向日葵毛状体作为模型系统来研究SLs生物合成中的碳流。在毛状体中，两种不同细胞类型（光合作用和非光合作用）的协调将通过标记前体饲养试验、关键酶的原位免疫定位、原位RNA杂交和单细胞型基因组学来研究。提出的多方面分析将阐明SLs是如何在复合材料的毛状体中合成和运输的，并将为SLs通量工程提供理论依据。