Physiological and Molecular Analysis of the Cyanobacterial CO2 Concentrating Mechanism

我的研究考察了一组称为蓝藻和微藻的水生微生物的光合作用过程。这些生物体是更新我们大气中的氧气供应、能量捕获和初级生产力的重要全球贡献者，它们约占“绿色生物体”固定的二氧化碳的40%。它们是我们湖泊和海洋食物链的基础，也是支持许多其他生物生命的基本食物来源。*我的具体研究考察了蓝藻如何从其水环境中捕获二氧化碳和碳酸氢盐，将它们输送到细胞中，并将它们浓缩用于光合作用。这种二氧化碳浓缩机制(CCM)非常有趣，因为在我们的大多数农作物中没有发现类似的过程。许多科学家认为，如果我们能将CCM特性从蓝藻转移到选定的陆地植物上，我们就有可能提高农作物的产量。CCM如何在蓝藻中发挥作用是我研究的主要重点。我们感兴趣的是定义CCM所需的基因和蛋白质，它们在细胞中是如何组织的，以及它们如何相互作用以增强光合作用。该系统的一个独特部分是被称为羧基体的蛋白质结构。这些结构在所有蓝藻中都存在，但在大多数其他生物中不存在。这是蓝藻光合作用途径中的第一个生化反应发生的地方。在过去的几年里，我们已经发现了几种称为碳水解酶的酶，它们对于羧基体中CCM的工作是必不可少的。我们目前正在探索这些蛋白质如何对光合作用做出贡献，它们如何调节碳流，以及它们如何在分子水平上发挥作用。我们已经在蓝藻的羧基体中鉴定出4个独立的蛋白质亚复合体，它们出现在表面，执行类似的生化功能。通过比较研究，我们将研究这些复合体在特定蓝藻物种中的作用，并确定一个或多个亚复合体是否为生长和生存提供竞争优势，并优先增强光合作用。

My research examines parts of the photosynthesis process in a group of aquatic microorganisms called cyanobacteria and microalgae. These organisms are important global contributors to the renewal of the oxygen supply in our atmosphere, energy capture and primary productivity and account for about 40% of the carbon dioxide that is fixed by "green organisms". They are the foundation of the food chain in our lakes and oceans and are essential food sources that support the lives of many other organisms.***My specific research examines how cyanobacteria capture carbon dioxide and bicarbonate from their aquatic environment, transport them into the cells and concentrate them for use in photosynthesis. This carbon dioxide concentrating mechanism (CCM) is very interesting since similar processes are not found in most of our crop plants. Many scientists think that we could potentially increase agricultural crop yield if we could transfer the CCM trait from cyanobacteria to selected land plants. How the CCM works in cyanobacteria is the main focus of my research. We are interested in defining the genes and proteins that are required for the CCM, how they are organized in the cell and how they interact with one another to enhance photosynthesis. One unique part of the system is protein structures called carboxysomes. These structures are found in all cyanobacteria, but not in most other organisms. This is where the first biochemical reaction in the photosynthetic pathway of cyanobacteria occurs. Over the past few years we have discovered several enzymes called carbonic anhydrases that are essential to the workings of the CCM in carboxysomes. We are currently exploring how these proteins contribute to photosynthesis, how they regulate the flow of carbon, and how they function at a molecular level. We have identified 4 separate protein sub-complexes in the carboxysomes of cyanobacteria that appear on the surface to perform a similar biochemical function. Through comparative studies we will examine the role of these complexes in specific cyanobacterial species and determine if one or more of the sub-complexes provide a competitive advantage to growth and survival and preferentially enhance photosynthesis.*****