Mechanisms of light regulated translation in chloroplasts

来自阳光的能量通过光合作用为地球上的生命提供燃料。光既是一种必要的资源，也是一种压力的来源，因为它通过一种被称为光氧化过程的过程破坏光合装置和其他细胞结构。因此，植物已经进化出了优化光利用、最小化光诱导损伤和促进光合机构修复的机制。在这项研究中，光调节合成的一个基因产物对这一过程至关重要，D1，将被检查。D1的合成速度随着光强的变化而迅速变化，因此本项目的目标是阐明介导D1的信号通路和机制。年代的回应。这个问题将通过玉米和拟南芥的遗传、分子和生化方法来解决。这些活动将为两名本科生、一名博士生和一名高中教师提供研究培训。此外，将探索有可能推动其他主题研究的新方法。要测试的假设来自最近的核糖体分析数据，该数据提供了光对叶绿体翻译影响的第一个全基因组视图。将采用玉米和拟南芥的遗传、分子和生化方法，包括鉴定体内与特定RNA结合的蛋白质的最先进方法，以及涉及设计RNA结合蛋白的新策略。一组实验将验证这样一种假设，即结合psbA 5'非翻译区的蛋白质的翻译后修饰介导了psbA mRNA（编码D1）上核糖体占用的快速变化。第二组实验将验证翻译延伸率的全局变化是由蛋白质的光依赖性翻译后修饰介导的，这些修饰会使核糖体停滞或催化翻译延伸。第三组实验将探讨光是否通过触发其他适应光合作用的信号转导途径诱导这些反应。最后，实验将验证叶绿体中基因特异性翻译调节因子的假设，包括那些根据光照调节翻译的基因，通常通过调节核糖体结合位点附近的RNA结构来起作用。本项目由分子和细胞生物科学部的遗传机制项目和综合生物系统部的植物基因组研究项目共同资助。

Energy from sunlight fuels life on earth through the process of photosynthesis. Light is both an essential resource and a source of stress, in that it damages the photosynthetic apparatus and other cellular structures through a process called photo-oxidative processes. As such, plants have evolved mechanisms that optimize the use of light, minimize light-induced damage, and promote repair of the photosynthetic apparatus should it occur. In this study the light-regulated synthesis of a gene product essential to this process, D1, will be examined. The rate of D1 synthesis changes rapidly in response to shifting light intensity and therefore the goal of this project is to elucidate the signaling pathways and mechanisms that mediate D1?s response. This problem will be addressed through genetic, molecular, and biochemical approaches in maize and Arabidopsis. These activities will provide research training for two undergraduate students, one PhD student, and a high school teacher. In addition, novel methods will be explored that have the potential to propel research on other topics. The hypotheses to be tested arise from recent ribosome profiling data that provide the first genome-wide views of the impact of light on translation in chloroplasts. Genetic, molecular, and biochemical approaches in maize and Arabidopsis will be employed, including a state-of-the-art method for identifying proteins bound to specific RNAs-of-interest in vivo, and a novel strategy involving designer RNA binding proteins. One set of experiments will test the hypothesis that the rapid light-induced change in ribosome occupancy on psbA mRNA (which encodes D1) is mediated by post-translational modification of proteins that bind the psbA 5' untranslated region. A second set of experiments will test the hypothesis that the global change in translation elongation rate is mediated by light-dependent post-translational modifications of proteins that stall ribosomes or catalyze translation elongation. A third set of experiments will address whether light induces these responses via the same signal transduction pathways that trigger other adaptations in response to photosynthetic activity. Finally, experiments will test the hypothesis that gene-specific translational regulators in chloroplasts, including those that regulate translation in response to light, generally act by modulating RNA structure proximal to ribosome binding sites.This project is co-funded by the Genetic Mechanisms Program in the Division of Molecular and Cellular Biosciences and by the Plant Genome Research Program in the Division of Integrative Organismal Systems.