Anoxygenic Photosynthesis in Cyanobacteria

蓝藻的缺氧光合作用

• 批准号: 1939303
• 负责人: Trinity Hamilton
• 金额: $ 38.49万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-06-01 至 2024-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1939303&HistoricalAwards=false
• 关键词: Anoxygenic; Photosynthesis; Cyanobacteria

Understanding the evolution of photosynthesis, the process of using light energy to convert carbon dioxide (CO2) into biomass, remains an outstanding question. A number of factors confound our ability to trace the evolution of photosynthesis: associated observed chemical limitations are not clearly defined in genetic information and horizontal gene transfer (the transfer of genetic information between microorganisms) hinders phylogenetic approaches. In the absence of characterized deeply-branching microorganisms, a robust phylogenomic framework, and undisputed biosignatures in the rock record, facultative anoxygenic photosynthesis in extant cyanobacteria represents an opportunity to better understand and constrain the evolution of photosynthesis. In this project, the investigator will characterize photosynthesis in an emerging model cyanobacterium, Leptolyngbya sp. strain hensonii, isolated from an anoxic, sulfide-rich sinkhole. This research will evaluate the genetic response of Leptolyngbya sp. strain hensonii to the presence of sulfide (which has been linked to inhibition of oxygenic photosynthesis) and the potential for a cyanobacterium to express a single photosystem based on environmental conditions. Collectively, the data will provide insight into the physiology and potential success of cyanobacteria prior to the evolution of oxygenic photosynthesis. The study will examine the role of life in the transformation and evolution of Earth's geochemical cycles and the evolution of photosynthesis, which is an outstanding question in geobiology. The project will train a graduate student and an undergraduate student. In addition, the research team will develop a demonstration for Market Science to broadly disseminate findings at Farmers' Markets in and around the Twin Cities area of Minnesota.The ability to harvest light and fuel cellular processes through phototrophy is arguably one the most important biological innovations in Earth history. Yet, understanding the evolution of photosynthesis remains an outstanding question in geobiology. Oxygenic photosynthesis is often cited as the most important microbial innovation having tipped the scale from a reducing early Earth to an oxygenated world that eventually lead to complex life. However, oxygenic phototrophs use two reaction centers: Photosystem II and Photosystem I for light-driven oxidation of water to fuel primary productivity. In extant sunlit environments where low oxygen concentrations and sulfide persist, some cyanobacteria can use sulfide as the electron donor to photosystem I, performing anoxygenic photosynthesis. In the absence of characterized deeply-branching isolates, a robust phylogenomic framework, and irrefutable biosignatures in the rock record, facultative anoxygenic photosynthesis in extant cyanobacteria represents a tractable system for examining the evolution of photosynthesis including the potential for an early evolving one-photosystem cyanobacterium. The proposed research plan will integrate a set of physiological studies coupled with systems biology approaches—transcriptomics and proteomics—to characterize an emerging model cyanobacterium isolated from a sulfidic, anoxic environment. The following objectives will guide this work: 1) define the molecular machinery necessary for anoxygenic photosynthesis; 2) characterize the effects of sulfide on photosystem II during anoxygenic photosynthesis; 3) determine oxidation kinetics of sulfide during anoxygenic photosynthesis; 4) examine the enhancement of carbon fixation in the presence of sulfide. The proposed research will examine the role of life in the transformation and evolution of Earth's geochemical cycles and the evolution of photosynthesis.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

光合作用是利用光能将二氧化碳（CO2）转化为生物质的过程，了解光合作用的进化仍然是一个悬而未决的问题。许多因素阻碍了我们追踪光合作用进化的能力：相关的观察到的化学限制在遗传信息中没有明确定义，水平基因转移（微生物之间的遗传信息转移）阻碍了系统发育方法。在缺乏特征化的深分支微生物、健全的系统基因组框架和岩石记录中无可争议的生物特征的情况下，现存蓝藻的兼性无氧光合作用为更好地理解和限制光合作用的进化提供了机会。在这个项目中，研究者将描述一种新型蓝藻的光合作用，leptolyynbya sp. strain hensonii，从缺氧，富含硫化物的天坑中分离出来。本研究将评估lepolyynbya sp.菌株hensonii对硫化物存在的遗传反应（硫化物与含氧光合作用的抑制有关）以及蓝藻根据环境条件表达单一光系统的潜力。总的来说，这些数据将为蓝藻在氧气光合作用进化之前的生理学和潜在成功提供见解。这项研究将探讨生命在地球地球化学循环的转变和进化以及光合作用的进化中的作用，这是地球生物学的一个突出问题。该项目将培养一名研究生和一名本科生。此外，研究小组将为市场科学开发一个示范，在明尼苏达州双城地区及其周围的农贸市场广泛传播研究结果。通过光养获得光和为细胞过程提供燃料的能力可以说是地球历史上最重要的生物创新之一。然而，了解光合作用的进化仍然是地球生物学中一个悬而未决的问题。含氧光合作用通常被认为是微生物最重要的创新，它使早期的地球从减少到最终产生复杂生命的含氧世界。然而，富氧光养生物使用两个反应中心：光系统II和光系统I来进行水的光驱动氧化，以促进初级生产力。在现有的低氧浓度和硫化物持续存在的阳光照射环境中，一些蓝藻可以使用硫化物作为光系统I的电子供体，进行无氧光合作用。在缺乏特征化的深分支分离物、健全的系统基因组框架和岩石记录中无可辩驳的生物特征的情况下，现存蓝藻中的兼性无氧光合作用代表了一个可处理的系统，用于研究光合作用的进化，包括早期进化的单光系统蓝藻的潜力。拟议的研究计划将整合一系列生理学研究，结合系统生物学方法-转录组学和蛋白质组学-来表征从硫化物，缺氧环境中分离出来的新兴蓝藻模型。以下目标将指导这项工作：1)定义无氧光合作用所需的分子机制；2)表征了无氧光合作用过程中硫化物对光系统II的影响；3)测定无氧光合作用过程中硫化物的氧化动力学；4)检查硫化物存在时碳固定的增强。拟议的研究将检查生命在地球地球化学循环的转变和进化以及光合作用的进化中的作用。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。