Introduction

Photosystem II (PSII) protein complex plays an essential role in the entire photosynthesis process. Various known and unknown protein factors are involved in the dynamics of the PSII complex that need to be characterized in crop plants for enhancing photosynthesis efficiency and productivity.

Objectives

The experiments were conducted to decipher the regulatory proteins involved in PSII dynamics of rice crop.

Methods

A novel rice regulatory protein PAP90 (PSII auxiliary protein ~90 kDa) was characterized by generating a loss-of-function mutant pap90. The mutation was characterized at molecular level followed by various experiments to analyze the morphological, physiological and biochemical processes of mutant under control and abiotic stresses.

Results

The pap90 mutant showed reduced photosynthesis due to D1 protein instability that subsequently causes inadequate accumulation of thylakoid membrane complexes, especially PSII and decreases PSII functional efficiency. Expression of OsFtsH family genes and proteins were induced in the mutant, which are known to play a key role in D1 protein degradation and turnover. The reduced D1 protein accumulation in the mutant increased the production of reactive oxygen species (ROS). The accumulation of ROS along with the increased activity of antioxidant enzymes and induced expression of stress-associated genes and proteins in pap90 mutant contributed to its water-limited stress tolerance ability.

Conclusion

We propose that PAP90 is a key auxiliary protein that interacts with D1 protein and maintains its stability, thereby promoting subsequent assembly of the PSII and associated membrane complexes.

中文翻译：

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PAP90，一种新型水稻蛋白在调节 PSII D1 蛋白稳定性中起关键作用

介绍

光系统 II (PSII) 蛋白质复合物在整个光合作用过程中起着至关重要的作用。各种已知和未知的蛋白质因子都涉及 PSII 复合物的动态，需要在作物植物中对其进行表征以提高光合作用效率和生产力。

目标

进行实验以破译参与水稻作物 PSII 动态的调节蛋白。

方法

一种新型水稻调节蛋白 PAP90（PSII 辅助蛋白 ~90 kDa）的特征在于产生功能丧失的突变体pap90。该突变在分子水平上进行了表征，然后进行了各种实验，以分析受控和非生物胁迫下突变体的形态、生理和生化过程。

结果

所述pap90突变体显示出降低的光合作用由于D1蛋白质的不稳定性，其随后导致类囊体膜复合物的积累不足，特别是PSII并降低PSII功能效率。在突变体中诱导OsFtsH家族基因和蛋白质的表达，已知它们在 D1 蛋白质降解和转换中起关键作用。突变体中 D1 蛋白积累的减少增加了活性氧 (ROS) 的产生。ROS 的积累以及抗氧化酶活性的增加以及pap90突变体中胁迫相关基因和蛋白质的诱导表达有助于其限水胁迫耐受能力。

结论

我们提出 PAP90 是一种关键的辅助蛋白，它与 D1 蛋白相互作用并保持其稳定性，从而促进 PSII 和相关膜复合物的后续组装。