State Key Laboratory of Crop Biology, Shandong Collaborative Innovation Center for Fruit and Vegetable Production with High Quality and Efficiency, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-An, Shandong 271018, China.
State Key Laboratory of Crop Stress Biology for Arid Areas/Shaanxi Key Laboratory of Apple, College of Horticulture, Northwest A&F University, Yang-Ling, Shaanxi 712100, China.
Plant Physiol. 2022 Aug 29;190(1):305-318. doi: 10.1093/plphys/kiac279.
The ubiquitin ligase CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1) plays a central role in light-induced anthocyanin biosynthesis. However, the upstream regulatory factors of COP1 remain poorly understood, particularly in horticultural plants. Here, we identified an MdCOP1-interacting protein, BROAD-COMPLEX, TRAMTRACK AND BRIC A BRAC2 (MdBT2), in apple (Malus domestica). MdBT2 is a BTB protein that directly interacts with and stabilizes MdCOP1 by inhibiting self-ubiquitination. Fluorescence observation and cell fractionation assays showed that MdBT2 increased the abundance of MdCOP1 in the nucleus. Moreover, a series of phenotypic analyses indicated that MdBT2 promoted MdCOP1-mediated ubiquitination and degradation of the MdMYB1 transcription factor, inhibiting the expression of anthocyanin biosynthesis genes and anthocyanin accumulation. Overall, our findings reveal a molecular mechanism by which MdBT2 positively regulates MdCOP1, providing insight into MdCOP1-mediated anthocyanin biosynthesis.
泛素连接酶 CONSTITUTIVELY PHOTOMORPHOGENIC 1（COP1）在光诱导的花青素生物合成中起着核心作用。然而，COP1 的上游调节因子仍知之甚少，特别是在园艺植物中。在这里，我们在苹果（Malus domestica）中鉴定到一个 MdCOP1 互作蛋白 BROAD-COMPLEX，TRAMTRACK AND BRIC A BRAC2（MdBT2）。MdBT2 是一个 BTB 蛋白，通过抑制自身泛素化来直接与 MdCOP1 相互作用并稳定其。荧光观察和细胞分馏实验表明，MdBT2 增加了 MdCOP1 在核中的丰度。此外，一系列表型分析表明，MdBT2 促进了 MdCOP1 介导的 MdMYB1 转录因子的泛素化和降解，抑制了花青素生物合成基因和花青素积累的表达。总的来说，我们的研究结果揭示了 MdBT2 正向调控 MdCOP1 的分子机制，为 MdCOP1 介导的花青素生物合成提供了新的见解。
