Wang Xiaoyun, Wu Jianghao, Li Hongxin, Liu Ying, Han Dexian, Dong Danhui, Zhang Jialong, Zhang Lixin, Zhang Na, Guo Yang-Dong
College of Horticulture, China Agricultural University, Beijing, 100193, China.
College of Plant Science and Technology, Beijing University of Agriculture, Beijing, 102206, China.
Mol Hortic. 2025 Aug 6;5(1):39. doi: 10.1186/s43897-025-00164-0.
State transition is a dynamic process to balance the amount of light energy received by photosystem I (PSI) and photosystem II (PSII) so as to maintain an optimal photosynthetic yield and to minimize photo-damage in a fluctuating light environment. Recent studies show that chloroplast acetyltransferase participates in the acetylation of photosynthetic proteins and state transitions. However, the exact molecular mechanisms are poorly understood. In this study, we characterized a chloroplast acetyltransferase in Solanum lycopersicum, SlGNAT2, and found that mutants lacking this enzyme are deficient in state transitions and retarded in growth under fluctuating light. Acetyltransferase activity assays and fluorescence measurements suggest that Lys of mature SlLhcb2 protein is a target of SlGNAT2 and might be involved in state transitions. In addition, Cys-related redox changes of SlGNAT2 affect its acetylation activity on SlLhcb2 and influence the assembly of the PSI-LHCI-LHCII supercomplex. Therefore, we propose that the chloroplast redox state may regulate the activity of SlGNAT2 which in turn acetylates SlLhcb2 and mediates state transitions in higher plants.
状态转换是一个动态过程，用于平衡光系统I（PSI）和光系统II（PSII）接收的光能数量，以便在波动的光照环境中维持最佳光合产量并使光损伤最小化。最近的研究表明，叶绿体乙酰转移酶参与光合蛋白的乙酰化和状态转换。然而，确切的分子机制尚不清楚。在本研究中，我们对番茄中的一种叶绿体乙酰转移酶SlGNAT2进行了表征，发现缺乏这种酶的突变体在状态转换方面存在缺陷，并且在波动光照下生长受阻。乙酰转移酶活性测定和荧光测量表明，成熟的SlLhcb2蛋白的赖氨酸是SlGNAT2的作用靶点，可能参与状态转换。此外，SlGNAT2的半胱氨酸相关氧化还原变化影响其对SlLhcb2的乙酰化活性，并影响PSI-LHCI-LHCII超级复合体的组装。因此，我们提出叶绿体氧化还原状态可能调节SlGNAT2的活性，进而使SlLhcb2乙酰化并介导高等植物中的状态转换。
