Collaborative Research: Elucidating the Influence of Metal Binding on Electronic/Geometric Structure-Function Relationships in Photorespiration

合作研究：阐明金属结合对光呼吸中电子/几何结构-功能关系的影响

• 批准号: 1904310
• 负责人: Kyle Lancaster
• 金额: $ 44.5万
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-08-01 至 2023-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1904310&HistoricalAwards=false
• 关键词: Collaborative; Research; Elucidating; Influence; Metal

In this project funded by the Chemistry of Life Processes Program of the Chemistry Division, Professors Kyle M. Lancaster of the Cornell University and Arnold J. Bloom of the University of California Davis evaluate the role of differential metal binding, specifically magnesium versus manganese, on the mechanisms and bioenergetics of photorespiration in which Rubisco, the most prevalent protein on the planet, reacts with oxygen rather than with carbon dioxide. This collaboration between a bioinorganic spectroscopist and a plant physiologist seeks to provide new perspectives on the evolution of photosynthesis and the relationships between plant carbon and nitrogen balances under past, present, and future environmental conditions. Such information is critical for maintaining food quality and ensuring world food security in the coming decades. Professors Lancaster and Bloom disseminate this information through articles in the online Encyclopedia of Earth, workshops at scientific meetings, including some organized by Societies of scientists who are members of groups underrepresented in STEM careers, and by writing and keeping up-to-date printed and online textbooks used by students as well as by American and foreign professionals whose work is related to environmental change. The proposed research involves application of a broad range of spectroscopic, kinetics, and computational techniques to contrast protein structure and plant metabolism when manganese or magnesium binds to the enzymes that catalyze the first three chemical steps in the photorespiratory pathway. The Mn2+-bound forms of Rubisco, malic enzyme, and phosphoglycolate phosphatase are characterized by X-ray crystallography and by electron spin resonance, X-ray absorption, and magnetic circular dichroism spectroscopy. Both isolated, intact chloroplasts as well as purified photorespiratory enzymes are studied. The work with isolated chloroplasts involves ratiometric dye measurements of magnesium and manganese concentrations, optode measurements of O2 and CO2 consumption, and mass spectrometric assessment of photorespiratory products. Work carried out on isolated enzymes involves measurement of electron transfer kinetics from manganese Rubisco during oxygenation of ribulose-1,5-bisphosphate as well as investigation of potential physiologically relevant electron transfer partners. The research tests the hypothesis that photorespiration is not a wasteful process, but one that generates reductant to support the conversion of nitrate and sulfate into amino acids. Therefore, C3 carbon fixation may be much more energy efficient than previously assumed.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.

在这个由化学系生命过程化学项目资助的项目中，康奈尔大学的 Kyle M. Lancaster 教授和加州大学戴维斯分校的 Arnold J. Bloom 教授评估了差异金属结合（特别是镁与锰）对光呼吸机制和生物能的作用，其中 Rubisco（地球上最常见的蛋白质）与氧而不是碳发生反应。 二氧化碳。生物无机光谱学家和植物生理学家之间的合作旨在为光合作用的进化以及过去、现在和未来环境条件下植物碳氮平衡之间的关系提供新的视角。此类信息对于维持食品质量和确保未来几十年的世界粮食安全至关重要。兰卡斯特和布鲁姆教授通过在线地球百科全书上的文章、科学会议上的研讨会（包括由在 STEM 职业中代表性不足的群体成员的科学家协会组织的一些研讨会）以及编写和保持学生以及从事与环境变化相关的美国和外国专业人士使用的最新印刷和在线教科书来传播这些信息。 拟议的研究涉及应用广泛的光谱、动力学和计算技术，以对比当锰或镁与催化光呼吸途径中前三个化学步骤的酶结合时的蛋白质结构和植物代谢。 Rubisco、苹果酸酶和磷酸乙醇酸磷酸酶的 Mn2+ 结合形式通过 X 射线晶体学、电子自旋共振、X 射线吸收和磁圆二色光谱进行表征。研究了分离的完整叶绿体以及纯化的光呼吸酶。分离叶绿体的工作涉及镁和锰浓度的比率染料测量、O2 和 CO2 消耗的光极测量以及光呼吸产物的质谱评估。对分离酶进行的工作包括测量 1,5-二磷酸核酮糖氧化过程中锰 Rubisco 的电子转移动力学，以及研究潜在的生理相关电子转移伙伴。 该研究测试了这样的假设：光呼吸不是一个浪费的过程，而是一个产生还原剂以支持硝酸盐和硫酸盐转化为氨基酸的过程。因此，C3 碳固定可能比之前假设的能源效率更高。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。