Regulation of iron-homeostasis in the chloroplast of Chlamydomonas reinhardtii: Dynamic remodeling of the photosynthetic machinery in response to iron availability

铁缺乏对几乎所有形式的生命都是一个严重的营养问题，因为铁虽然天然丰富，但生物利用度有限。呼吸和光合作用的生物能膜是铁的主要细胞汇，因为在这些途径中有丰富的血红素和铁硫蛋白。在这个项目中解决的一个问题是如何在不同程度的缺铁反应中改变氧化还原能量代谢。利用莱茵衣藻的光合器官作为实验模型，可以应用逆向遗传学和蛋白质组学等全系统方法解决这一问题。该提案旨在验证以下假设：在缺铁依赖的褪绿表型变得明显之前，存在一个诱导特异性反应的调节网络。该网络感知细胞或亚细胞铁含量，并控制蛋白质表达水平，以调节各种过程，包括铁稳态和光合机制的重塑过程。我们将阐明在叶绿体铁稳态中运作的调控网络，重点是在铁缺乏的情况下，质体中调节生物能量途径的机制，特别是控制和建立光系统I （PSI）及其光收集蛋白（LHCI）重塑的机制。

Iron-deficiency is a serious nutritional problem for nearly all forms of life because the limited bioavailability of iron despite its natural abundance. The bioenergetic membranes of respiration and photosynthesis are a major cellular sink for iron because of the abundance of heme and iron-sulfur proteins in these pathways. A question addressed in this project is how redox energy metabolism is modified in response to various degrees of iron-deficiency. It is proposed to use the photosynthetic apparatus of the green alga Chlamydomonas reinhardtii as the experimental model because we can apply reverse genetics and whole systems approaches like proteomics to this problem. The proposal is designed to test the following hypothesis: There is a regulatory network that induces specific responses before an iron-deficiency dependent chlorotic phenotype becomes evident. This network senses the cellular or sub-cellular iron content and controls protein expression levels to regulate various processes including iron homeostasis and the remodeling process of the photosynthetic machinery. We will elucidate regulatory networks that operate in chloroplast iron-homeostasis with a focus on mechanisms that modulate bioenergetic pathways in the plastids in response to iron-deficiency and in particular on mechanisms that control and establish remodeling of photosystem I (PSI) and its light-harvesting proteins (LHCI).