Evolution of CYP6B Genes Associated with Furanocoumarin Metabolism in the Papilio Glaucus Group

绝大多数毛毛虫以种类有限的植物为食，通常只在一个科内。这些特殊的取食者的显著特征之一是酶解毒系统，包括细胞色素P450单加氧酶，它们被理想地配置为代谢其寄主植物的典型毒素。然而，虎燕尾（Papilio glaucus）及其近亲在毛虫中是例外的，因为它们可以以更广泛的植物科为食。在这样做的过程中，他们会遇到种类繁多的植物毒素，这些毒素的生物合成来源和结构各不相同。本项目旨在确定虎凤尾及其通用型亲缘植物的细胞色素P450单加氧酶的生物化学和分子生物学特性与凤蝶属中它们的特殊亲缘植物的P450系统的差异。大多数凤蝶都专门以含有呋喃香豆素毒素的植物为食，这些物种依靠CYP6B家族中的p450来解毒。虽然它们很少遇到这些化合物，但虎燕尾也能代谢这些化合物，尽管速度较低。在这个项目中，CYP6B基因的结构和调控的差异将在凤蝶属中被绘制出来(1)，以了解在专门的谱系中如何产生普遍的习惯，(2)确定P450的进化如何促进解毒能力的变化。

The vast majority of caterpillars feed on a narrow range of plants, often within only a single family. Among the distinguishing characteristics of such specialized feeders are enzymatic detoxification systems, including cytochrome P450 monooxygenases, that are ideally configured for metabolizing the toxins that typify their hostplants. The tiger swallowtail (Papilio glaucus) and its relatives, however, are exceptional among caterpillars in that they can feed on a much broader range of plant families. In doing so they encounter a substantially greater diversity of plant toxins, which differ in their biosynthetic origin and structure. This project is aimed at determining how the biochemistry and molecular biology of the cytochrome P450 monooxygenases of the tiger swallowtail and its generalist relatives differ from the P450 systems in their specialized relatives in the genus Papilio. Most Papilio species are specialized for feeding on plants containing toxins called furanocoumarins, and these species rely on P450s in the CYP6B family for detoxification. Although they rarely encounter them, tiger swallowtails can metabolize these compounds too, albeit at lower rates. In this project, differences in the structure and regulation of the CYP6B genes will be mapped within the genus Papilio (1) in order to understand how generalized habits can arise within specialized lineages and (2) to determine how P450 evolution can contribute to changes in detoxification capabilities.