Bilateral NSF/BIO-BBSRC: Synthesis of Microcompartments in Plants for Enhanced Carbon Fixation

对粮食和燃料的需求正在稳步增长，生物学的一个主要挑战是找到提高作物产量的方法。 一个潜在的途径是提高光合作用。酶Rubisco（核酮糖-1，5-二磷酸羧化酶/加氧酶）可以催化核酮糖-1，5-二磷酸与二氧化碳的结合，但也可以催化核酮糖-1，5-二磷酸与氧气的反应，这是一个损失先前固定的二氧化碳的过程。蓝细菌和一些陆地植物具有将二氧化碳集中在Rubisco酶附近的机制，该酶阻止其与氧气反应，这一过程称为碳浓缩机制。 然而，许多全球重要的作物植物缺乏这种能力。在这个合作项目中，来自美国（康奈尔大学）和英国（兰开斯特大学和格拉斯哥大学）的研究人员试图使用新开发的合成生物学工具在缺乏这种能力的工厂中创建碳浓缩系统。该项目提供了跨学科的培训机会，包括与他们的国际合作者，在定量和合成生物学。 提高光合产量的一个策略是用一种更快的酶沿着碳浓缩机制来取代作物植物的Rubisco。本项目的总体目标是建立烟草中蓝藻碳浓缩机制的模型系统。 这将通过设计、构建和测试三个组成部分来实现：1）将核编码的碳酸氢盐转运蛋白工程化到叶绿体包膜上; 2）去除叶绿体碳酸酐酶;以及3）从叶绿体基因组表达所有的蓝藻羧基体蛋白。将进行生化和微观研究，以确定蓝藻蛋白质的化学计量对微区室大小，形态和功能的碳浓度和光合作用的影响。 叶绿体转化体将进行分析，以确定所需的合成叶绿体操纵子中的基因调控序列的功能，以表达蛋白质的数量和比例所需的组装microcompartments.This美国/英国合作项目是由美国国家科学基金会和英国生物技术和生物科学研究理事会的支持。

Demand for food and fuel is steadily increasing and a major challenge in biology is to discover ways to increase crop productivity. One potential route is by improving photosynthesis. The enzyme Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase) can catalyze the combination of ribulose-1,5-bisphophate with carbon dioxide, but also can catalyze the reaction of ribulose-1,5-bisphophate with oxygen, a process in which previously fixed carbon dioxide is lost. Cyanobacteria and some land plants have mechanisms that concentrate carbon dioxide near the enzyme Rubisco that prevents it from reacting with oxygen, a process called carbon concentrating mechanism. However, many of the globally important crop plants lack this ability. In this collaborative project investigators from the US (Cornell University) and the UK (Lancaster University and Glasgow University) seek to use newly developed synthetic biology tools to create a carbon concentrating system in a plant that lacks this capability. The project provides interdisciplinary training opportunities, including with their international collaborators, in quantitative and synthetic biology. One strategy to improve photosynthetic yields is to replace a crop plant's Rubisco with a faster enzyme along with a carbon-concentrating mechanism. The overall goal of this project is to build the cyanobacterial carbon concentrating mechanism in tobacco as a model system. This will be accomplished by designing, building, and testing three component parts: 1) engineering a nuclear-encoded bicarbonate transporter onto the chloroplast envelope; 2) removing the chloroplast carbonic anhydrase; and 3) expressing all of the cyanobacterial carboxysome proteins from the chloroplast genome. Biochemical and microscopic studies will be performed to determine the effect of stoichiometry of cyanobacterial proteins on microcompartment size, morphology, and function in carbon concentration and photosynthesis. Chloroplast transformants will be analyzed to determine the features of the gene regulatory sequences in the synthetic chloroplast operons needed to express proteins in the amounts and ratios needed for assembly of microcompartments.This collaborative US/UK project is supported by the US National Science Foundation and the UK Biotechnology and Biological Sciences Research Council.