Dynamic Regulation of the Form and Function of Photosystem II, a Membrane Protein Complex

膜蛋白复合物光系统 II 的形式和功能的动态调节

• 批准号: 0745611
• 负责人: Himadri Pakrasi
• 金额: $ 93.95万
• 依托单位: Washington University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-04-15 至 2015-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0745611&HistoricalAwards=false
• 关键词: Dynamic; Regulation; Form; Function; Photosystem

ABSTRACTThis project focuses on understanding the dynamic regulation of the multisubunit pigment protein complex Photosystem II (PSII). Localized in the thylakoid membrane of cyanobacteria, algae and plants, PSII catalyzes light-induced electron transfer from water to plastoquinone with concomitant evolution of oxygen. The life history of PSII is intriguing in that its normal function leads to rapid turnover of this large integral membrane protein complex. This process, undoubtedly carefully orchestrated to maintain critically important water oxidation activities, must require a host of assembly factors, very few of which have been identified to date. Also, oxygenic photosynthetic organisms in general, and cyanobacteria in particular, inhabit almost every ecological niche on the planet, surviving in temperatures from 4 degrees Celsius to 75 degrees Celsius, under widely varying nutritional environs. Recent genome level data suggest that among such organisms, PSII exhibits a high degree of plasticity in both composition and regulation to optimize its function. For example, N2-fixing cyanobacteria such as Cyanothece 51142 are capable of oxygenic photosynthesis and N2 fixation in single cells. These two metabolic processes are at odds with each other, since the N2-fixing enzyme, nitrogenase, is highly sensitive to O2. To resolve this conflict, these organisms have developed a type of temporal regulation in which N2 fixation and photosynthesis occur at different times throughout a diurnal cycle. Again, little is known about how the form and function of PSII are regulated so that every night, PSII becomes inactive.The specific aims of this project are:I. To investigate the dynamic forms of PSII under diverse environmental conditions.A. To examine diurnal regulation of PSII activity in Cyanothece 51142.B. To elucidate the effect of chloride concentration on the composition of the lumenal proteins of PSII in Synechocystis as well as Prochloroccous.II. To examine the assembly intermediates of PSII in Synechocystis 6803.A. To investigate PSII assembly intermediates over a time course.B. To define the functions of various lumenal proteins in PSII biogenesis.C. To elucidate the role of the assembly intermediate operon (aio) in PSII biogenesis.Broader ImpactBy harvesting solar radiation, the PSII complex contributes to nearly half of the biomass and bioenergy production on our planet. A detailed understanding of the dynamic nature PSII is necessary to fully comprehend the mechanism of photosynthetic O2-evolution. This project will encompass a broad genomics based approach to provide a multi-disciplinary training environment for all researchers. The project will also help train a number of undergraduate, graduate and post-doctoral students in the general area of bioenergy. Finally, the on-going tradition of all researchers in this project participating in significant outreach activities will be continued.

摘要本项目的重点是了解多亚基色素蛋白复合物光系统II（PSII）的动态调节。PSII定位于蓝藻、藻类和植物的类囊体膜中，催化光诱导的电子从水到质体醌的转移，伴随着氧的释放。PSII的生活史是有趣的，因为它的正常功能导致这个大的完整的膜蛋白复合物的快速周转。 这一过程，无疑精心策划，以保持至关重要的水氧化活动，必须需要一系列的组装因素，其中很少已经确定的日期。此外，一般来说，产氧光合生物，特别是蓝细菌，几乎栖息在地球上的每一个生态位，在4摄氏度至75摄氏度的温度下，在营养环境变化很大的情况下生存。 最近的基因组水平的数据表明，在这些生物体中，PSII表现出高度的可塑性，在组成和调节，以优化其功能。例如，N2固定蓝细菌如蓝杆藻51142能够在单细胞中进行产氧光合作用和N2固定。这两个代谢过程是相互矛盾的，因为固氮酶，固氮酶，是高度敏感的O2。为了解决这一冲突，这些生物已经开发出一种时间调节，其中N2固定和光合作用在整个昼夜循环的不同时间发生。 同样，人们对PSII的形式和功能是如何调节的，以至于每天晚上PSII都变得不活跃的知之甚少。研究不同环境条件下PSII的动态变化.研究蓝杆藻（Cyanothece 51142.B.）阐明氯离子浓度对集胞藻和原绿球藻PSII腔蛋白组成的影响。研究集胞藻6803.A中PS Ⅱ的组装中间体。研究PSII组装中间体随时间的变化。明确各种胞腔蛋白在PSII生物发生中的功能。阐明组装中间操纵子（aio）在PSII生物发生中的作用。更广泛的影响PSII复合体通过收集太阳辐射，贡献了地球上近一半的生物质和生物能源生产。 详细了解PSII的动态性质是充分理解光合放氧机制的必要条件。该项目将包括一个广泛的基因组学为基础的方法，为所有研究人员提供一个多学科的培训环境。该项目还将帮助培养一些生物能源领域的本科生、研究生和博士后学生。最后，本项目所有研究人员参与重大外联活动的传统将继续下去。