Ciesielska Maria, Adamiec Małgorzata, Luciński Robert
Department of Plant Physiology, Institute of Experimental Biology, Faculty of Biology, Adam Mickiewicz University in Poznań, ul Uniwersytetu Poznańskiego 6, 61-614 Poznań, Poland.
Plants (Basel). 2025 Aug 20;14(16):2584. doi: 10.3390/plants14162584.
High light intensity constitutes a critical abiotic stress factor that profoundly affects the structural and functional integrity of the photosynthetic apparatus. Excessive irradiance triggers accelerated degradation of the PsbA polypeptide, increases susceptibility to photoinhibition, and promotes overproduction of reactive oxygen species (ROS), thereby inducing oxidative damage to proteins, lipids, and nucleic acids. Among the chloroplast-localized site-2 proteases of , remains the least characterized. In this study, our analyses revealed a pronounced upregulation of the (AT1G05140) gene and a concomitant accumulation of the protein under high light conditions. Functional characterization using two independent insertional mutant lines lacking the protease demonstrated that loss of significantly exacerbates photoinhibition. Mutants exhibited reduced photosystem II (PSII) efficiency, accompanied by accelerated degradation of the PSII core proteins PsbA, PsbD, and PsbC, as well as elevated ROS generation. These findings provide the first direct evidence that plays a pivotal role in maintaining the stoichiometric balance of PSII core components and conferring resilience of the photosynthetic machinery to high light stress. This work expands the functional repertoire of chloroplast site-2 proteases and underscores as a potential target for improving stress tolerance in plants.
高光强度是一种关键的非生物胁迫因素，会深刻影响光合机构的结构和功能完整性。过度光照会引发光系统II反应中心蛋白（PsbA）多肽的加速降解，增加对光抑制的敏感性，并促进活性氧（ROS）的过量产生，从而对蛋白质、脂质和核酸造成氧化损伤。在叶绿体定位的2型蛋白酶中，[具体蛋白酶名称]的特征最少。在本研究中，我们的分析表明，在高光条件下，[具体基因名称]（AT1G05140）基因显著上调，且[具体蛋白名称]蛋白随之积累。使用两个独立的缺乏该蛋白酶的插入突变株系进行功能表征表明，[具体蛋白酶名称]的缺失显著加剧了光抑制。突变体表现出光系统II（PSII）效率降低，同时PSII核心蛋白PsbA、PsbD和PsbC加速降解，以及ROS生成增加。这些发现提供了首个直接证据，表明[具体蛋白酶名称]在维持PSII核心组分的化学计量平衡以及赋予光合机构对高光胁迫的恢复力方面起着关键作用。这项工作扩展了叶绿体2型蛋白酶的功能谱，并强调[具体蛋白酶名称]是提高植物胁迫耐受性的潜在靶点。
