Physiological and Molecular Analysis of the Cyanobacterial CO2 Concentrating Mechanism

我的研究考察了一组被称为蓝藻和微藻的水生微生物光合作用过程的一部分。这些生物在全球范围内对我们大气中的氧气供应、能量捕获和初级生产力的更新做出了重要贡献，约占“绿色生物”固定二氧化碳的40%。它们是我们湖泊和海洋食物链的基础，是支持许多其他生物生命的重要食物来源。***我的具体研究考察了蓝藻如何从水生环境中捕获二氧化碳和碳酸氢盐，将它们运输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作物植物中没有发现类似的过程。许多科学家认为，如果我们能将蓝细菌的CCM特性转移到选定的陆地植物上，我们就有可能提高农作物产量。CCM如何在蓝藻中起作用是我研究的主要焦点。我们感兴趣的是定义CCM所需的基因和蛋白质，它们如何在细胞中组织，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称为羧酸体的蛋白质结构。这些结构在所有蓝藻细菌中都有，但在大多数其他生物中没有。这是蓝藻光合途径中第一个生化反应发生的地方。在过去的几年里，我们发现了几种被称为碳酸酐酶的酶，它们对羧酸体中CCM的工作至关重要。我们目前正在探索这些蛋白质如何促进光合作用，它们如何调节碳的流动，以及它们如何在分子水平上起作用。我们已经在蓝藻的羧酸体中发现了4个单独的蛋白质亚复合物，它们出现在表面上，执行类似的生化功能。通过比较研究，我们将检查这些复合物在特定蓝藻物种中的作用，并确定一个或多个亚复合物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.*****