OPR Protein-mediated Control and Adaption of Chloroplast Gene Expression in Chlamydomonas

由于叶绿体的内共生起源，现在许多构成类囊体膜的多亚基复合物的蛋白质在细胞核中编码，而其他蛋白质在叶绿体本身编码。因此，叶绿体基因表达需要与细胞核协调，以允许蛋白质复合物的平衡组装。此外，细胞器的基因表达需要适应不断变化的环境，特别是光，以满足细胞的需求。迄今为止，八肽重复蛋白（OPRs）在绿藻叶绿体基因转录后调控中的主要作用才刚刚出现。藻类基因组编码的大部分OPRs的RNA靶点及其分子工作模式尚不清楚。此外，opr与其质体靶rna的特异性相互作用使其成为叶绿体基因表达调节因子的理想人选，以适应不断变化的光照条件。由于光系统II （PSII）最容易受到光损伤，因此该项目的重点是在模式生物莱茵衣藻（Chlamydomonas reinhardtii）中确认或预期在PSII亚基表达中起作用的OPRs。为了进一步深入了解opr介导的叶绿体基因表达的控制和调控，我们的目标是(I)阐明参与稳定编码PSII亚基的两个mrna的两个opr的精确分子工作模式，（II）鉴定参与PSII生物发生的新opr， （III）研究这些opr对细胞器光依赖适应过程的影响。

Due to the endosymbiotic origin of chloroplasts, many of the proteins constituting the multisubunit complexes of the thylakoid membrane are nowadays encoded in the nucleus while others are encoded in the chloroplast itself. Chloroplast gene expression therefore needs to be coordinated with the nuclear one to allow a balanced assembly of protein complexes. In addition, gene expression of the organelle requires an adaption to a changing environment, in particular light, to meet the demand of the cell. To date, the predominant role of Octotricopeptide Repeat proteins (OPRs) as key players for the posttranscriptional control of chloroplast gene expression in green algae is just emerging. The RNA targets of the majority of OPRs encoded by the algal genome as well as their molecular working modes are unknown. Moreover, the specific interaction of OPRs with their plastid target RNAs makes them ideal candidates as regulators of chloroplast gene expression for an adaption to changing light conditions. As photosystem II (PSII) is most susceptible to photodamage, the focus of the proposed project lies on OPRs with confirmed or expected functions in the expression of PSII subunits in the model organism Chlamydomonas reinhardtii. To gain further important insights into the OPR-mediated control and regulation of chloroplast gene expression, we aim at (I) elucidating the precise molecular working mode of two OPRs involved in the stabilization of two mRNAs encoding PSII subunits, (II) identify new OPRs involved in PSII biogenesis and (III) investigate the impact of these OPRs on light-dependent adaptive processes of the organelle.