Fujian Provincial Key Laboratory of Plant Functional Biology, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
Int J Mol Sci. 2022 May 20;23(10):5754. doi: 10.3390/ijms23105754.
Catabolism of macromolecules is a major event in senescent cells, especially involving proteolysis of organelles and abnormally aggregated proteins, circulation of nutrients, and precise control of intracellular environmental balance. Proteasomes are distributed in the nucleus and cytoplasm; however, proteasomes in organelles are limited. In this study, multi-omics proteomic analyses of ubiquitinated proteins enriched by using antibody against "di-Gly-Lys" via a free labeling were used to investigate the global changes of protein levels and ubiquitination modification levels of mutant relative to wild-type plant; subcellular localization analysis of UPL5 was found to be located in the nucleus, cytoplasm, and plastid within the cell; and the direct lysine site patterns of UPL5 were screened by the H89R substitution in the tagged ubiquitinated assay. It suggests that UPL5 acting as a candidate of organelle E3 ligase either in the nucleus or cytoplasm or plastid modifies numerous targets related to nuclear transcription and plastid photosynthesis involving in Ca and hormone signaling pathway in plant senescence and in response to (a)biotic stress protection.
大分子的分解代谢是衰老细胞中的一个主要事件，特别是涉及到细胞器和异常聚集蛋白的蛋白水解、营养物质的循环以及细胞内环境平衡的精确控制。蛋白酶体分布在细胞核和细胞质中；然而，细胞器中的蛋白酶体是有限的。在这项研究中，通过使用针对"二甘氨酸-赖氨酸"的抗体进行自由标记，对泛素化蛋白进行了多组学蛋白质组学分析，以研究突变体相对于野生型植物的蛋白质水平和泛素化修饰水平的全局变化；发现 UPL5 的亚细胞定位分析定位于细胞内的细胞核、细胞质和质体；并通过在标记的泛素化测定中用 H89R 取代筛选 UPL5 的直接赖氨酸位点模式。这表明 UPL5 作为核内或细胞质或质体 E3 连接酶的候选物，修饰与核转录和质体光合作用相关的大量靶标，涉及植物衰老和对（非生物）胁迫保护的 Ca 和激素信号通路。
