CAPP: Combining Algal and Plant Photosynthesis

很明显，我们需要提高农作物产量来养活不断增长的人口。RuBisCO酶对所有植物将二氧化碳固定为糖至关重要，但它的低效率使其成为光合作用的主要瓶颈。为了弥补RuBisCO的低效率，具有被称为“C-3”光合作用过程的植物（如水稻和小麦）投入了很大一部分资源来生产RuBisCO蛋白质，该蛋白质占其叶片总蛋白质的50%。与C3植物不同，许多藻类已经开发出一种方法，通过使用生物物理碳浓缩机制（CCM）来大幅减少有效光合作用所需的RuBisCO蛋白的数量。CCM增加了RuBisCO所在的类pyrenoid亚细胞内的二氧化碳浓度，从而增强了较少RuBisCO蛋白对二氧化碳的同化。该项目雄心勃勃的目标是将绿藻衣藻（Chlamydomonas）的CCM转移到C3模式植物拟南芥（Arabidopsis）中，从而提高二氧化碳同化率。该计划将使用尖端的全基因组筛选来发现藻类CCM的新成分，包括类pyrenoid成分。已知和新发现成分的生理功能、定位和物理相互作用将通过分子和细胞生物学方法进行表征，包括电子显微镜和质谱分析。将开发一个修饰的RuBisCO并将其插入拟南芥中，以形成类pyrenoid细胞器。已知成分和逐渐发现的关键新成分将转移到拟南芥中，并评估它们对光合作用的影响。这一过程将得到先进计算模型发展的指导和支持。通过从绿藻中引入生物物理CCM，这一变革性项目代表了C3作物在提高光合效率方面的飞跃。此外，该研究将为藻类CCM提供更清晰的分子定义，这是一个非常重要但鲜为人知的生物过程。这项研究将为本科生提供从广泛的生物学研究基础中学习的机会。

There is a clear need to increase crop productivity to feed our growing population. The enzyme RuBisCO is critical for the fixation of carbon dioxide into sugars in all plants, but its low efficiency makes it a major bottleneck in photosynthesis. To compensate for RuBisCO's low efficiency, plants with a photosynthetic process known as "C-3" (such as rice and wheat) devote a large fraction of their resources to producing the RuBisCO protein, which constitutes up to 50% of the total protein in their leaves. Unlike C3 plants, many algae have developed a means to drastically reduce the amounts of RuBisCO protein needed for efficient photosynthesis, by using a biophysical carbon concentrating mechanism (CCM). The CCM increases the carbon dioxide concentration within a subcellular compartment called the pyrenoid where RuBisCO is located, thus enhancing carbon dioxide assimilation with less RuBisCO protein.The ambitious goal of this program is to transfer the CCM from the green alga Chlamydomonas to the model C3 plant Arabidopsis, thus improving rates of carbon dioxide assimilation. The program will use a cutting-edge genome-wide screen to discover novel components of the algal CCM, including pyrenoid components. The physiological functions, localizations and physical interactions of known and newly-discovered components will be characterized by molecular and cell biological approaches, including electron microscopy and mass spectrometry. A modified RuBisCO will be developed and inserted into Arabidopsis to enable formation of a pyrenoid-like organelle. Known components and, progressively, key newly-discovered components, will be transferred to Arabidopsis and their impact on photosynthesis will be assessed. The process will be guided and supported by the development of advanced computational models.This transformative program represents a leap forward towards improving the photosynthetic efficiency of C3 crop plants, by introduction of a biophysical CCM from green algae. Additionally, the research will provide a much clearer molecular definition of the algal CCM, which is a fundamentally important yet poorly understood biological process. The research will provide undergraduate students opportunities to learn from a broad base of biological research.