FvCSN5 对抑制剂 FvMYB1 和激活剂 FvBBX20 的泛素介导的降解平衡了草莓果实中花青素的生物合成
The Plant Journal ( IF 6.2 ) Pub Date : 2025-03-12 , DOI: 10.1111/tpj.70021
Yuxin Nie 1 , Yingying Lei 1 , Hongbo Jiao 1 , Zhuo Zhang 1 , Jinxiang Yao 1 , He Li 1 , Hongyan Dai 1 , Zhihong Zhang 1 , Junxiang Zhang 1
摘要CPN5 被广泛认为是 COP9 信号体的亚基，CSN5 主要参与植物生长发育，以及对生物和非生物胁迫的耐受性。然而，CSN5 调节植物花青素生物合成的分子机制在很大程度上仍然未知。在这里，我们使用花青素通路抑制剂 MYB1 作为诱饵，从林地草莓酵母双杂交文库中鉴定了 FvCSN5。我们通过 H2Y、Pull-down、LCI 和 BiFC 测定证明了 FvCSN5 和 FvMYB1 的相互作用。FvCSN5 在所有测试组织中表达，并定位于细胞核和胞质溶胶中，具有自激活活性。FvCSN5 在林地草莓中的稳定过表达减少了果实中花青素的积累。与野生型植物相比，过表达 FvCSN5 植物的 FvMYB1 蛋白水平大大降低。蛋白质降解测定和 MG-132 处理 （一种阻断 26S 蛋白酶体活性的蛋白酶体抑制剂） 显示 FvCSN5 通过泛素化途径降解 FvMYB1。此外，FvCSN5 还与花青素激活剂 FvBBX20 相互作用，FvBBX20 可被 FvCSN5 降解。此外，瞬时表达分析显示，当 FvCSN5 分别与 FvMYB1 和 FvBBX20 共表达时，花青素生物合成基因 FvCHS 和 FvF3H 的表达量显著增加和降低。这些结果表明，FvMYB1-FvCSN5-FvBBX20 是一种新型的三元复合物，通过泛素化途径调节花青素的生物合成。
Ubiquitin‐mediated degradation of the inhibitor FvMYB1 and the activator FvBBX20 by FvCSN5 balances anthocyanin biosynthesis in strawberry fruit
SUMMARYPlant CSN5 is widely recognized as the subunit of the COP9 signalosome and CSN5 is mainly involved in plant growth and development, and tolerance to biotic and abiotic stresses. However, the molecular mechanism of CSN5 regulating anthocyanin biosynthesis in plants is still largely unknown. Here, we identified FvCSN5 from the woodland strawberry yeast two‐hybrid library using the anthocyanin pathway inhibitor MYB1 as bait. We demonstrated the interaction of FvCSN5 and FvMYB1 by H2Y, Pull‐down, LCI, and BiFC assays. FvCSN5 was expressed in all test tissues and localized in the nucleus and cytosol with self‐activation activity. Stable overexpression of FvCSN5 in woodland strawberries reduced anthocyanin accumulation in fruits. The protein level of FvMYB1 greatly decreased in overexpressing FvCSN5 plants compared with wild‐type plants. Protein degradation assay and MG‐132 treatment (a proteasome inhibitor blocking 26S proteasome activity) revealed FvCSN5 degraded FvMYB1 through the ubiquitination pathway. In addition, FvCSN5 also interacted with the anthocyanin activator FvBBX20 and FvBBX20 could be degraded by FvCSN5. Moreover, transient expression analysis showed the expression of anthocyanin biosynthetic genes FvCHS and FvF3H was greatly increased and decreased when FvCSN5 was co‐expressed with FvMYB1 and FvBBX20, respectively. These results indicate that FvMYB1‐FvCSN5‐FvBBX20 is a novel ternary complex that regulates anthocyanin biosynthesis by the ubiquitination pathway.
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