蓝细菌Synechococcus elongatus PCC 7942二氧化碳浓缩系统的生物合成与动态调控机制

植物光合作用受限于光合CO2固定中的关键酶Rubisco的低效催化反应，成为目前提高作物产量的主要限制因素之一。蓝细菌在进化中形成了独特的CO2浓缩机制(CCM)，在Rubisco周围大量富集CO2，从而提高光合作用效率。蓝细菌CCM由胞质中的羧酶体和位于质膜和类囊体膜上的无机碳转运/吸收膜蛋白系统组成。目前对CCM中各蛋白复合物如何在蓝细菌体内合成并协同工作来高效的引导细胞内碳流尚不清楚。本项目在前期的研究基础上，将综合运用微生物学、分子遗传学、生物化学、细胞生物学和结构生物学方法，深入解析羧酶体和各CCM成分的原位合成、定位、结构、功能和相互协作的分子机理。本项目不仅将为全面揭示蓝细菌CCM的生物合成和工作机制提供重要的实验证据，还将指导利用合成生物学在异源宿主（例如作物植物）中构建有活性的CCM体系，以提高光合碳固定效率和产量，并利用现代生物技术为粮食、能源安全提供科学的解决方案。

A prime limitation of crop plant photosynthesis is the inefficient reaction catalysed by ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), the key enzyme for CO2 fixation. This represents the main factor restricting crop productivity today. Cyanobacteria have evolved powerful CO2-concentrating mechanisms (CCM) that can accumulate CO2 around Rubisco by up to 1000-fold than the cellular CO2 levels, and thereby, vastly improve photosynthetic performance. The cyanobacterial CCM consist of the central CO2-fixing organelles in the cytosol – the carboxysomes – and inorganic carbon uptake systems in the plasma and thylakoid membranes. How are these CCM components are synthesized and work effectively together within the cyanobacterial cells remain unclear. In this proposed research project, we will use multidisciplinary approaches in microbiology, molecular genetics, biochemistry, cell biology and structural biology to obtain an advanced level of understanding of the subcellular localization, biogenesis, structures, functions and regulation of carboxysomes and other cyanobacterial CCM components, as well as their physiological coordination to direct carbon flow. The overall research outcomes will not only provide new insights into the biosynthesis, organisation and functionality of cyanobacterial CCM, but also inform the design and synthetic engineering of functional CCM circuits in other hosting organisms, such as crop plants, to boost photosynthetic carbon fixation and productivity. Standing on this project, we anticipate the development of a long-term research strength with the intend of using modern microbiology and biotechnology to provide scientific solutions for safeguarding global food and energy security.