Division of Life Sciences, Korea University, Seoul, 02841, Republic of Korea.
Division of Life Science, Applied Life Science (BK21 Plus Program), Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, Gyeongnam, 52828, Republic of Korea.
Plant Cell Rep. 2021 Apr;40(4):677-689. doi: 10.1007/s00299-021-02663-y. Epub 2021 Jan 25.
TCX8 localizes to nucleus and has transcriptional repression activity. TCX8 binds to the promoter region of LOX2 encoding lipoxygenase, causing JA biosynthesis suppression, and thereby delays plant senescence. Conserved CXC domain-containing proteins are found in most eukaryotes. Eight TCX proteins, which are homologs of animal CXC-Hinge-CXC (CHC) proteins, were identified in Arabidopsis, and three of them, TSO1, TCX2/SOL2 and TCX3/SOL1, have been reported to affect cell-cycle control. TCX8, one of the TCX family proteins, was believed to be a TF but its precise function has not been reported. Yeast two-hybrid screening revealed TCP20, a TF that binds to the promoter of LOX2 encoding lipoxygenase, as a strong candidate for interaction with TCX8. We confirmed that TCX8 directly interacts with TCP20 using in vitro pull-down assay and in vivo BiFC and observed that TCX8, as a TF, localizes to nucleus. Using EMSA and by analyzing phenotypes of TCX8-overexpression lines, we demonstrated that TCX8 regulates the expression of LOX2 by binding to either cis-element of LOX2 promoter to which TCP20 or TCP4 binds, affecting JA biosynthesis, and thereby delaying plant senescence. Our study provides new information about the role of TCX8 in modulating plant senescence through regulating LOX2 expression.
TCX8 定位于细胞核，具有转录抑制活性。TCX8 与编码脂氧合酶的 LOX2 的启动子区域结合，导致 JA 生物合成受到抑制，从而延缓植物衰老。大多数真核生物中都存在保守的 CXC 结构域蛋白。在拟南芥中鉴定出了 8 种 TCX 蛋白，它们是动物 CXC-Hinge-CXC（CHC）蛋白的同源物，其中 TSO1、TCX2/SOL2 和 TCX3/SOL1 三种已被报道影响细胞周期控制。TCX8 是 TCX 家族蛋白之一，被认为是一种 TF，但它的确切功能尚未报道。酵母双杂交筛选显示，与编码脂氧合酶的 LOX2 启动子结合的 TF TCP20 是与 TCX8 相互作用的强候选物。我们通过体外下拉测定和体内 BiFC 证实了 TCX8 与 TCP20 直接相互作用，并观察到 TCX8 作为一种 TF 定位于细胞核。通过 EMSA 并分析 TCX8 过表达系的表型，我们证明了 TCX8 通过与 TCP20 或 TCP4 结合的 LOX2 启动子顺式元件结合来调节 LOX2 的表达，影响 JA 生物合成，从而延缓植物衰老。我们的研究提供了关于 TCX8 通过调节 LOX2 表达来调节植物衰老的作用的新信息。
