Collaborative Research: Multiple Approaches to Gain Increased Capture of Carbon Dioxide

21世纪世纪最重要的挑战之一是确保世界70多亿人口的粮食安全。植物利用光合作用的过程来利用阳光的能量将二氧化碳转化为食物和纤维，帮助养活和维持世界人口。负责这一过程的酶（RuBisCO）将二氧化碳结合到糖中，但它也将氧气结合到植物无法使用的产品（乙醇酸盐）中，因此必须分解和回收;据估计，植物捕获的太阳光能中有高达30%因此被浪费。二氧化碳和氧气竞争酶RuBisCO上的结合位点，因此提高植物生产力的一种方法是提高植物细胞中二氧化碳相对于氧气的浓度。在这项由美国和英国研究人员组成的合作研究计划中，这一目标将通过设计一个由阳光驱动的生物泵来实现，该生物泵将大气中的二氧化碳输送到植物细胞中，集中并储存在那里用于光合作用。该项目涉及植物生物学家，生物化学家，生物化学家，蛋白质设计师，化学工程师和数学建模师的大型跨学科团队。该项目将为本科生、研究生和博士后研究人员提供教育和培训机会，所有这些人都在高度合作的国际科学背景下工作。此外，还提供了面向公众的公共宣传，包括出版物、公开讲座和面向公众的网站。增加光合作用中可用于固定的二氧化碳量将通过光驱动的碳酸氢盐泵和支架来实现，以保留二氧化碳，直到它可以被核酮糖二磷酸羧化酶/加氧酶（RuBisCo）固定。这将通过向叶绿体和蓝细菌中引入蛋白质盐视紫红质（halorhodopsin）来实现，盐视紫红质利用光来泵送氯离子，AE 1是一种氯离子/碳酸氢盐交换剂，以实现净光驱动的碳酸氢盐运输。在一个平行的策略中，盐视紫红质将被修饰以直接运输碳酸氢盐以及利用可见光谱之外的光。碳酸酐酶在叶绿体中释放的二氧化碳需要保留足够长的时间才能与RuBisCO反应。为了实现这一目标，将设计分子支架将二氧化碳输送到RuBisCO，包括二氧化碳海绵和工程反向C4途径。数学建模将把理论与运输和脚手架工作中的实验联系起来。使用光驱动的碳酸氢盐泵和二氧化碳支架/海绵的方法有可能将叶绿体内的二氧化碳分压提高高达60%，从而允许RuBisCO固定的二氧化碳与氧气的比率大幅增加。该奖项由分子和细胞生物科学部的细胞动力学和功能群以及化学、生物工程、环境和运输系统部的生物技术、生物化学和生物质工程项目共同支持。

One of the foremost challenges of the 21st century is to ensure food security for the world's population of over 7 billion people. Plants use the process of photosynthesis to harness the energy of sunlight to convert carbon dioxide into food and fiber that helps feed and clothe the world's population. The enzyme responsible for this process (RuBisCO) incorporates carbon dioxide into sugars, but it also incorporates oxygen into a product (glycolate) that cannot be used by the plant and therefore must be broken down and recycled; it is estimated that up to 30% of the light energy from the sun that is captured by a plant is thereby wasted. Carbon dioxide and oxygen compete for the binding site on the enzyme RuBisCO thus one way to increase plant productivity would be to raise the concentration of carbon dioxide relative to that of oxygen in the plant cell. In this collaborative research program engaging teams of researchers from the US and the United Kingdom, this goal will be addressed by engineering a biological pump, driven by sunlight, that will transport atmospheric carbon dioxide into the plant cell, concentrating and storing it there for use in photosynthesis. This project engages a large interdisciplinary team of plant biologists, biochemists, biophysicists, protein designers, chemical engineers, and mathematical modelers. This project will provide educational and training opportunities for undergraduate students, graduate students and postdoctoral researchers, all working in a highly cooperative, international scientific context. There are also provisions for public outreach, including publications, public talks, and websites geared toward the general public.Increasing the amount of carbon dioxide available for fixation in photosynthesis will be achieved with a light-driven bicarbonate pump and a scaffold to retain the carbon dioxide until it can be fixed by ribulosebisphosphate carboxylase/oxygenase (RuBisCo). This will be accomplished by introducing into chloroplasts and cyanobacteria the proteins halorhodopsin which uses light to pump chloride ions, and AE1, a chloride/bicarbonate exchanger, to achieve net light-driven bicarbonate transport. In a parallel strategy, halorhodopsin will be modified to transport bicarbonate directly as well as to utilize light outside the visible spectrum. The carbon dioxide released in the chloroplast by carbonic anhydrase needs to be retained long enough to react with RuBisCO. To accomplish this, molecular scaffolds will be designed for the delivery of carbon dioxide to RuBisCO, including a carbon dioxide sponge and an engineered reverse C4 pathway. Mathematical modeling will link theory with experiment in both the transport and scaffolding efforts. The approach of using a light-driven bicarbonate pump and a carbon dioxide scaffold/sponge has the potential to raise the partial pressure of carbon dioxide by up to 60% inside the chloroplast, thereby allowing a large increase in the ratio of carbon dioxide to oxygen fixed by RuBisCO. The consequence to the plant should be a significantly higher photosynthetic productivity in the laboratory as well as in the field.This award is supported jointly by the Cellular Dynamics and Function Cluster in the Division of Molecular and Cellular Biosciences and by the Biotechnology, Biochemical and Biomass Engineering Program in the Division of Chemical, Bioengineering, Environmental and Transport Systems.