光合作用除了将CO₂和水转化成糖和氧气以及能量以外，还生产大量的天然化学产物（natural chemical compounds）。但在植物进化过程中，能量生产与活性物质的合成划分成两个场所：叶绿体和内质网。前者光合作用合成ATP和NADPH以及碳水化合物。而在内质网上的P450单加氧酶参与生物活性物质的合成，能量来自于NADPH电子传递。在内质网中NADPH的浓度限制了次生代谢物的合成速度。Poul Erik Jensen等人打破进化的限制，将整条次生代谢产物合成途径转到叶绿体中，直接利用NADPH，提高了次生代谢物质的产率。该研究通过利用叶绿体中的NADPH， 直接驱动P450快速合成天然化学物质。

图片来源于原文

 原文链接: Redirecting Photosynthetic Reducing Power toward Bioactive Natural Product Synthesis, DOI: 10.1021/sb300128r. http://pubs.acs.org/doi/abs/10.1021/sb300128r. 

Abstract

In addition to the products of photosynthesis, the chloroplast provides the energy and carbon building blocks required for synthesis of a wealth of bioactive natural products of which many have potential uses as pharmaceuticals. In the course of plant evolution, energy generation and biosynthetic capacities have been compartmentalized. Chloroplast photosynthesis provides ATP and NADPH as well as carbon sources for primary metabolism. Cytochrome P450 monooxygenases (P450s) in the endoplasmic reticulum (ER) synthesize a wide spectrum of bioactive natural products, powered by single electron transfers from NADPH. P450s are present in low amounts, and the reactions proceed relatively slowly due to limiting concentrations of NADPH. Here we demonstrate that it is possible to break the evolutionary compartmentalization of energy generation and P450-catalyzed biosynthesis, by relocating an entire P450-dependent pathway to the chloroplast and driving the pathway by direct use of the reducing power generated by photosystem I in a light-dependent manner. The study demonstrates the potential of transferring pathways for structurally complex high-value natural products to the chloroplast and directly tapping into the reducing power generated by photosynthesis to drive the P450s using water as the primary electron donor.