Intergrated biochemical genomics and cellular platform for alkaloid biosynthetic gene discovery and characterization

点击翻译按钮获取中文摘要

The unparalleled biosynthetic capacity of plants has long been exploited through the use of many species in traditional medicine and the application of pure metabolites as pharmaceuticals, flavours, fragrances, pigments, insecticides, and other fine chemicals. Benzylisoquinoline alkaloids (BIAs) are a large group of plant specialized metabolites derived from tyrosine and diversified by an intricate biochemical network of intramolecular coupling, reduction, methylation, hydroxylation, and other reactions that generate >2,500 known structures. Several BIAs (e.g. the analgesic morphine, the cough suppressant codeine, and the vasodilators papaverine and tubocurarine) serve directly as pharmaceuticals, or as precursors for semi-synthetic drugs (e.g. oxycodone). Plants remain the only economical source for these compounds due to their chemical complexity, which makes de novo synthesis challenging and costly. Most research on BIA metabolism has targeted biosynthetic enzymes and corresponding genes involved in the formation of relatively few compounds in only a limited number of species. An important feature of plant specialized metabolism is the ability of enzymes to acquire novel functions through random mutation. As such, a relatively limited number of enzyme types (i.e. SAM-dependent methyltransferases, acetylCoA-dependent acyltransferases, P450-dependent monooxygenases, FAD-dependent oxidoreductases, short-chain dehydrogenase/reductases and aldo-keto reductases) are largely responsible for the establishment of the diverse backbone structures and functional group substitutions responsible for BIA structural diversity. A functional genomics strategy based on the integration and comparison of metabolite and transcript profiles from a collection of cultured plant species will be used to identify and characterize novel BIA biosynthetic enzymes. Genomics resources and molecular genetic tools will be used to identify and modulate transcription factors involved in the regulation of BIA metabolism. The cellular and subcellular localization of newly discovered BIA biosynthetic enzymes will be determined, and possible enzyme interactions will also be investigated.