Tea Research Institute, Qingdao Agricultural University, Qingdao, 266109, China.
College of Life Science, Yantai University, Yantai, Shandong, 264005, China.
Sci Rep. 2019 Mar 12;9(1):4286. doi: 10.1038/s41598-019-41041-3.
Drought stress often affects the expression of genes and proteins in tea plants. However, the global profiling of ubiquitinated (Kub) proteins in tea plants remains unearthed. Here, we performed the ubiquitome in tea leaves under drought stress using antibody-based affinity enrichment coupled with LC-MS/MS analysis. In total, 1,409 lysine Kub sites in 781 proteins were identified, of which 14 sites in 12 proteins were up-regulated and 123 sites in 91 proteins down-regulated under drought stress. The identified Kub proteins were mainly located in the cytosol (31%), chloroplast (27%) and nuclear (19%). Moreover, 5 conserved motifs in EK, EXXXK, KD, KE and KA were extracted. Several Kub sites in ubiquitin-mediated proteolysis-related proteins, including RGLG2, UBC36, UEV1D, RPN10 and PSMC2, might affect protein degradation and DNA repair. Plenty of Kub proteins related to catechins biosynthesis, including PAL, CHS, CHI and F3H, were positively correlated with each other due to their co-expression and co-localization. Furthermore, some Kub proteins involved in carbohydrate and amino acid metabolism, including FBPase, FBA and GAD1, might promote sucrose, fructose and GABA accumulation in tea leaves under drought stress. Our study preliminarily revealed the global profiling of Kub proteins in metabolic pathways and provided an important resource for further study on the functions of Kub proteins in tea plants.
干旱胁迫通常会影响茶树基因和蛋白质的表达。然而，茶树泛素化（Kub）蛋白的全局分析仍未被揭示。在这里，我们使用基于抗体的亲和富集结合 LC-MS/MS 分析，研究了干旱胁迫下茶树叶片中的泛素组。总共鉴定了 781 种蛋白质中的 1409 个赖氨酸 Kub 位点，其中 12 种蛋白质中的 14 个位点在干旱胁迫下上调，91 种蛋白质中的 123 个位点下调。鉴定的 Kub 蛋白主要位于细胞质（31%）、叶绿体（27%）和核（19%）。此外，还提取了 EK、EXXXK、KD、KE 和 KA 中的 5 个保守基序。在泛素介导的蛋白水解相关蛋白中，包括 RGLG2、UBC36、UEV1D、RPN10 和 PSMC2，几个 Kub 位点可能会影响蛋白降解和 DNA 修复。许多与儿茶素生物合成相关的 Kub 蛋白，包括 PAL、CHS、CHI 和 F3H，由于它们的共表达和共定位而相互正相关。此外，一些参与碳水化合物和氨基酸代谢的 Kub 蛋白，包括 FBPase、FBA 和 GAD1，可能会促进干旱胁迫下茶树中蔗糖、果糖和 GABA 的积累。本研究初步揭示了代谢途径中 Kub 蛋白的全局分析，为进一步研究 Kub 蛋白在茶树中的功能提供了重要资源。
