EAGER: Collaborative Research: Manganese Phototrophy in Cyanobacteria

EAGER：合作研究：蓝藻中的锰光养作用

• 批准号: 1832939
• 负责人: Woodward Fischer
• 金额: $ 12.77万
• 依托单位: California Institute of Technology
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-01 至 2020-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1832939&HistoricalAwards=false
• 关键词: EAGER; Collaborative; Research; Manganese; Phototrophy

The rise of oxygen approximately 2.3 billion years ago was arguably the most significant event in Earth's history. The rise of atmospheric oxygen led to life as we know it today, including organisms that breath oxygen and multicellular life such as plants and animals. This event is principally related to the evolution of oxygen (O2) producing photosynthesis by Cyanobacteria. Photosystem II (PSII) is the catalyst that uses light energy to remove electrons from water and produce O2. The evolutionary route of PSII to produce O2 is uncertain. One hypothesis, based on both the geological record and biochemical studies of PSII, is a precursor photosystem was able to obtain electrons from the transition metal manganese, instead of water. The proposed work tests this hypothesis using modern Cyanobacteria and PSII, which may still be able to perform this reaction. The work will help scientists understand the evolution of this important process: the production of O2. It will also impact understanding of modern manganese cycling on our planet, which affects the fate of many pollutants in the environment. Students trained in this interdisciplinary research project from both a geobiology program at a research intensive university and a biological science program at a diverse regional Hispanic-serving primarily undergraduate institution will attend common group and professional meetings and develop mentor-mentee relationships across disciplines. Findings will also be integrated into presentations and coursework at K-12 and the two universities. This project concerns the hypothesis that the "missing link" in the evolution of photosynthetic water-oxidation by Photosystem II (PSII) was phototrophic Mn(II) oxidation, and examines Mn phototrophy in Cyanobacteria to test this hypothesis. High-valent manganese species comprise a critical pool of strong oxidants in the environment, involved in the cycling of both carbon and metals. This work will add to the understanding of modern biological Mn oxidation and the potential sources of high-valent Mn in nature by examining bacterial Mn oxidation in Mn phototrophy. Phototrophic Mn oxidation will be evaluated and linked to growth using whole cells of the genetically tractable Cyanobacterium, Synechocystis sp. PCC 6803, and a mutant of this organism impaired in photosynthesis. The stoichiometry and mechanism of Mn-oxidizing phototrophy will be determined using purified PSIIs from these strains. These studies have the potential to provide new insight into our understanding of the evolution of oxygenic photosynthesis. The broader impacts concern a research collaboration between a research intensive and primarily undergraduate institution that is also minority serving. Students from the two institutions will interact with each other and the research results will be incorporated into presentations and courses at the undergraduate and K-12 level.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.

大约23亿年前氧气的出现可以说是地球历史上最重要的事件。大气中氧气的增加导致了我们今天所知道的生命，包括呼吸氧气的生物和多细胞生物，如植物和动物。这一事件主要与蓝藻产生光合作用的氧气（O2）进化有关。光系统II （PSII）是利用光能从水中除去电子并产生O2的催化剂。PSII产生O2的进化途径尚不确定。根据地质记录和PSII的生化研究，有一种假设是前体光系统能够从过渡金属锰而不是水中获得电子。提出的工作使用现代蓝藻和PSII来测试这一假设，它们可能仍然能够进行这一反应。这项工作将帮助科学家了解这个重要过程的演变：氧气的产生。它还将影响我们对地球上现代锰循环的理解，这将影响环境中许多污染物的命运。在这个跨学科研究项目中，来自研究密集型大学的地理生物学项目和不同地区以西班牙裔为主的本科院校的生物科学项目的学生将参加共同的小组和专业会议，并发展跨学科的师徒关系。研究结果还将整合到K-12和两所大学的报告和课程中。本项目关注光系统II （PSII）光合水氧化进化中的“缺失环节”是光营养性Mn（II）氧化的假设，并研究蓝藻中的Mn光营养性来验证这一假设。高价锰物种构成了环境中一个重要的强氧化剂库，参与碳和金属的循环。这项工作将通过研究光养Mn中的细菌Mn氧化，增加对现代生物Mn氧化和自然界中高价Mn的潜在来源的理解。光营养性锰氧化将被评估，并与生长联系起来，使用遗传易感的蓝藻，Synechocystis sp. PCC 6803的整个细胞，以及该有机体在光合作用中受损的突变体。利用从这些菌株纯化的PSIIs来确定mn氧化光养的化学计量学和机制。这些研究有可能为我们理解含氧光合作用的进化提供新的见解。更广泛的影响涉及研究密集型和主要本科院校之间的研究合作，也为少数民族服务。两所大学的学生将相互交流，研究成果将被纳入本科和K-12阶段的演讲和课程中。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。