The integration of the cyclophilin 20-3 and 2-cysteine peroxiredoxin thiol switches in the redox regulatory network of the chloroplast

叶绿体含有一个物理和功能相互作用的调节蛋白模块，包括亲环素20-3(Cyp20-3)、2-半胱氨酸过氧化还蛋白(2-CysPrxA/B)、丝氨酸乙酰转移酶(SERAT2.1)和O-乙酰丝氨酸硫解酶(OASTL-B)，COPS模块。这个模块控制叶绿体半胱氨酸的合成，影响氧化还原动态平衡，干扰核基因的表达，如果受到损害，就会阻碍生长表现，特别是在压力下。Cyp20-3和2-CysPrx都是已建立的硫醇开关，除了它们在COPS模块中的特定作用外，还可能具有氧化还原依赖的功能。本项目旨在了解COPS模块的生理整合和氧化还原调节意义，重点是Cyp20-3。将在体外研究硫醇开关蛋白Cyp20-3的氧化还原控制，以剖析还原剂的效率并确定可能的氧化剂。Cyp20-3，2-CysPrx，SERAT2.1和OASTLB之间相互作用的结构要求将在转基因原生质体和拟南芥品系中进行探索。为此，将用Cyp20-3和2-CysPrx的定点突变变体来补充敲除品系。重点是COPS模块在细胞蛋白质动态平衡中的功能，这一点从属于这一特定基因本体论组的转录本的深刻解除管制中可见一斑。Cyp20-3和2-CysPrx在氧脂信号和碳水化合物代谢中的作用将被仔细研究，并与新的相互作用因子联系起来，涉及从叶绿体到细胞核的逆行信号传递。此外，该项目将解决COPS模块及其组件在平衡叶绿体电子分布方面的功能。最重要的假说假设COPS模块的组件有助于植物在生长或防御投资之间的代谢决定，以及光合作用电子传递链向不同消耗途径提供的还原功率的分配。

The chloroplast contains a physically and functionally interacting regulatory protein module consisting of cyclophilin 20-3 (Cyp20-3), 2-cysteine peroxiredoxin (2-CysPrxA/B), serine acetyl transferase (SERAT2.1) and O-acetylserine thiolyase (OASTL-B), the COPS module. This module controls plastid cysteine synthesis, affects redox homeostasis, interferes with nuclear gene expression and, if compromised, impedes growth performance, particularly under stress. Both Cyp20-3 and 2-CysPrx function as established thiol switches and likely have redox-dependent functions beyond their specific role within the COPS module. This projects aims to understand the physiological integration and redox regulatory significance of the COPS module with emphasis on Cyp20-3. The redox control of the thiol switch protein Cyp20-3 will be studied in vitro to dissect the efficiency of reductants and identify possible oxidants. Structural requirements for the interaction between Cyp20-3, 2-CysPrx, SERAT2.1 and OASTLB will be explored in transfected protoplasts and in Arabidopsis thaliana lines. To this end knockout lines will be complemented with site-directed mutated variants of Cyp20-3 and 2-CysPrx. Emphasis is given to functions of the COPS module in cellular protein homeostasis as indicated by the profound deregulation of transcripts belonging to this particular gene ontology group. The role of Cyp20-3 and 2-CysPrx in oxylipin signaling and carbohydrate metabolism will be scrutinized and linked to novel interactors and involved retrograde signaling from the chloroplast to the nucleus. Furthermore, the project will address the COPS module and its components for their function in balancing chloroplast electron distribution. The overarching hypothesis assumes that the components of the COPS module contribute to the metabolic decision of the plants between investment in growth or defense, and in the distribution of reducing power provided by the photosynthetic electron transport chain to the different consuming pathways.