Molecular regulation of light harvesting: Cytosolic translation control mediated by the nuclear encoded protein NAB1 in C. reinhardtii

翻译调控是调控细胞转录后基因表达的重要机制。在光养生物中，一些光合作用基因也在翻译水平上受到控制。这对于在细胞核中编码的光调节叶绿体蛋白尤其重要。在这种情况下，细胞质中稳定的mRNA库将使细胞对叶绿体中的事件做出更快的反应。然而，“准备使用”mRNA的存在需要一个依赖于应激的调节系统。直到最近，只有间接的证据表明这种转录后控制的存在。该项目的主要目标是表征NAB1，这是一种参与光捕获叶绿素结合蛋白翻译控制的关键蛋白，该蛋白先前已通过系统筛选莱茵衣藻随机插入突变体确定。该项目的重点是阐明其调控功能的机制，并确定其在光驯化过程中的信号作用。在植物模式生物衣藻中获得的结果将被转移到其他生物中，以评估翻译控制是否是植物界的共同机制。

Translation control in cells is known as an important mechanism that regulates the expression of genes on a post-transcriptional level. In phototrophic organisms some photosynthesis genes are also controlled at the translational level. This can be of particular importance for light-regulated chloroplast proteins that are encoded in the nucleus. In this case a steady state pool of mRNA in the cytosol would enable the cell to respond faster to events in the chloroplast. However, the existence of “ready to use” mRNA requires a stress-dependent regulation system. Until recently there was only indirect evidence which indicated the existence of such post-transcriptional control. The major objective of this project is to characterise NAB1, a key protein involved in translational control of light harvesting chlorophyll binding proteins which has been identified previously by systematic screens of Chlamydomonas reinhardtii random insertion mutants. The project focuses on elucidating the mechanisms of its regulatory function and defining its role in signalling during light acclimation. Results obtained in the plant model organism Chlamydomonas will then be transferred to other organisms to evaluate if translation control is a common mechanism within the plant kingdom.