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

摘要本项目主要研究多亚基色素蛋白复合体光系统II （PSII）的动态调控。PSII定位于蓝藻、藻类和植物的类囊体膜，催化光诱导电子从水中转移到质体醌，同时伴随氧气的进化。PSII的生活史是有趣的，因为它的正常功能导致这种大的完整膜蛋白复合物的快速周转。这一过程无疑是精心策划的，以维持至关重要的水氧化活性，必须需要大量的组装因素，迄今为止已确定的组装因素很少。此外，一般的含氧光合生物，特别是蓝藻，几乎栖息在地球上的每一个生态位，在4摄氏度到75摄氏度的温度下生存，在各种不同的营养环境下生存。最近的基因组水平数据表明，在这些生物中，PSII在组成和调节方面都表现出高度的可塑性，以优化其功能。例如，固定N2的蓝藻，如Cyanothece 51142，能够在单细胞中进行含氧光合作用和固定N2。这两种代谢过程是相互矛盾的，因为固定n2的酶，即氮酶，对O2非常敏感。为了解决这一冲突，这些生物已经发展出一种时间调节，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，对于PSII的形式和功能是如何被调节的知之甚少，因此每晚PSII都变得不活跃。该项目的具体目标是：1。探讨不同环境条件下PSII的动态形态。目的：探讨花蓝51142.B中PSII活性的昼夜调节。目的：探讨氯离子浓度对聚囊藻PSII和原氯霉素管腔蛋白组成的影响。目的研究聚胞菌6803.A中PSII的组装中间体。在一段时间内研究PSII组装中间体。目的：明确各种管腔蛋白在PSII生物发生中的作用。目的：阐明组装中间操纵子（aio）在PSII生物发生中的作用。更广泛的影响通过收集太阳辐射，PSII综合体贡献了地球上近一半的生物质能和生物能源生产。详细了解PSII的动态性质是充分理解光合o2演化机制的必要条件。该项目将涵盖广泛的基因组学方法，为所有研究人员提供多学科培训环境。该项目还将帮助培养生物能源领域的本科生、研究生和博士后。最后，本项目所有研究人员参与重要外联活动的传统将继续下去。

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.