Managing the dark:light transition by dynamic micro-compartmentalization in plant mitochondria

线粒体在所有复杂生命中都是常见的。它们宿主呼吸作为大量ATP的来源，ATP是为运动、生长和发育所需能量的细胞过程提供燃料所必需的。然而，在植物中，这种情况随着日出而改变。然后光合作用取代呼吸作用成为主导的生物能量过程，线粒体运作的生理环境经历了深刻的转变。光合作用极大地改变了细胞代谢物和辅因子库，并增加了局部氧气水平。线粒体机制不仅维持改变的细胞状态，而且支持有效的光合作用。这需要线粒体功能的主动再奉献，并意味着线粒体与叶绿体的严格协调。此外，它还包括植物特有的在明暗之间的周期性操作转换。在拟议的研究中，我们将通过分析黎明时蛋白质相互作用的动力学来解决绿色植物组织中线粒体功能在黑暗到光明过渡期间的快速驯化是如何编排的问题。酶与蛋白质复合物的结合导致微室的形成，减少了扩散距离，增加了通路的周转率。它还限制了分支反应或竞争反应造成的中间体损失，因此，提高了途径的代谢效率。对于哺乳动物和酵母线粒体蛋白：基质酶的蛋白质相互作用与潜在的调控意义已经被证明。在之前的一项研究中，植物中也发现了类似的相互作用。为了评估动态蛋白质：蛋白质相互作用在多大程度上影响植物黎明时线粒体代谢的调节，我们在这里提出了一种生物化学和遗传方法的结合，可以对这一主题进行广泛但（部分）详细的观察。功能分析将用于深入了解黎明前后线粒体的代谢状态，并将使蛋白质变化的直接相关性：蛋白质相互作用模式与线粒体生理状态的改变。连同另外两个作为植物线粒体新光计划的一部分提出的项目，这项研究将为光合生物线粒体功能的调节机制提供新的深度见解。

Mitochondria are common to all complex life. They host respiration as the source of the large amounts of ATP that are necessary to fuel energy-demanding cellular processes allowing movement, growth, and development. In plants, however, this situation changes with sunrise. Then photosynthesis takes over from respiration as the dominating bioenergetic process, and the physiological environment in which the mitochondria operate undergoes a profound transition. Photosynthesis drastically alters the cellular metabolite and cofactor pools and increases local oxygen levels. The mitochondrial machinery then not only sustains an altered cellular status, but supports efficient photosynthesis. This requires active re-dedication of mitochondrial function and implies strict coordination of the mitochondria with the chloroplasts. Moreover, it includes a periodic operational transition between light and dark that is unique to plants. In the proposed research, we will address the question how the rapid acclimation of mitochondrial functions during dark-to-light transitions is choreographed in green plant tissues by analysing the dynamics of protein:protein interactions at dawn. Association of enzymes to protein complexes leads to the formation of micro-compartments with reduced diffusion distances and increases turnover rates of pathways. It also limits losses of intermediates by branching or competing reactions and, as such, increases metabolic efficiency of pathways. For mammalian and yeast mitochondria protein:protein interactions of matrix enzymes with potential implications for regulation have already been shown. Similar interactions in plants were detected in a previous study. To assess to which extent dynamic protein:protein interactions impact on the adjustment of plant mitochondrial metabolism at dawn, we here propose a combination of biochemical and genetic approaches which enables a broad, yet (in parts) detailed view on this topic. Functional assays will be used to gain insight into the metabolic state of mitochondria before and after dawn and will enable direct correlation of changes in protein:protein interaction patterns with alterations of the physiological status of the mitochondria.Together with two other projects proposed as part of the Plant Mitochondria in a New Light initiative, this research will provide novel depth of insight into the mechanisms regulating mitochondrial function in photosynthetic organisms.