Light not only serves as an energy source for photosynthesis in plants but also acts as a signaling source influencing various physiological phenomena in plants, playing a crucial role throughout the plant growth process. Previous studies have indicated that light can enhance the efficiency of translational processes during photomorphogenesis, directly initiating protein synthesis related to chloroplasts, photosynthesis, and ribosomes. Compared to the well-understood transcriptional processes, translational processes have broader and more significant impacts as they directly affect protein generation and stability. However, the mechanisms regulating translational processes and selective protein synthesis in plants remain unclear, and little is known about the specific mechanisms induced by light affecting translational processes.
Assistant Professor Mei-Chun Cheng's research team at the Department of Biochemical Science and Technology, National Taiwan University, discovered that the phosphatase SPA (SUPPRESSOR OF PHYA-105) in Arabidopsis can promote translation by phosphorylating the eukaryotic translation initiation factor eIF2α under light stimulation. The SPA phosphatase translocates from the nucleus to the cytoplasm under light, interacts with eIF2α, and phosphorylates it. However, this phosphorylation site differs from the typical phosphorylation sites found in mammals and yeast; it is located at the C-terminus of eIF2α. Through the establishment of transgenic plants with various phosphorylation site mutations, the research team found that this phosphorylation can promote translation by enhancing the composition of the translation initiation factor complex, leading to photomorphogenesis in plants. By comparing protein sequences from different species, the research team found that animals lack the same C-terminal phosphorylation site as plants, once again demonstrating that plants have different regulatory mechanisms from animals. In summary, light can promote the phosphorylation of the C-terminus of eIF2α in plants and regulate translational efficiency. This research not only answers long-standing questions but also provides a new direction for future studies.
This study was published in the prestigious international journal "Nature Communications" in April 2024. The primary executor of the research was doctoral student Hui-Xian Chang, with co-authors Lin-Chen Huang, Dr. Enamul Huq from the University of Texas at Austin, and Dr. Karen S. Browning. The project was supported by the National Science Council. Full research paper: https://www.nature.com/articles/s41467-024-47848-7
Source: https://www.ntu.edu.tw/spotlight/2024/2266_20240515.html