UFL1介导的UFMylation稳定了ABI5，增强了拟南芥中ABA依赖的种子休眠

摘要(中文译文)

UFM化是一种可逆的类泛素修饰，在哺乳动物中具有新兴且重要的作用，但其在植物中的功能机制在很大程度上仍不清楚。本研究系统表征了拟南芥中完整的UFM化通路，并证明其核心组分——E1 UBA5、E2 UFC1和E3 UFL1——具有强效的酶活性。UFL1是一种E3连接酶，定位于细胞核和细胞质。表达模式分析显示，UFL1在胚胎发生过程中强烈上调，并在种子成熟过程中逐步积累。表型分析表明，UFL1过表达增强种子休眠、增加植物对脱落酸（ABA）的敏感性，并显著延迟种子萌发和子叶变绿，表明UFL1是此前未被认识的ABA信号正调控因子。生化分析进一步证明，UFL1与bZIP转录因子ABI5发生物理互作并介导其UFM化，从而拮抗泛素化并稳定ABI5蛋白丰度。遗传学证据进一步支持ABI5作用于UFL1下游以调控种子发育过程。总之，我们的发现揭示了UFM化是植物中的关键调控层面，并发现了一个协调种子成熟、休眠和萌发的UFL1-ABI5信号模块。

Abstract

UFMylation is a reversible ubiquitin-like modification with an emerging and essential role in mammals, yet its functional mechanisms in plants remain largely unknown. In this study, we systematically characterized the complete UFMylation pathway in Arabidopsis thaliana and demonstrated that its core components-E1 UBA5, E2 UFC1, and E3 UFL1-possessed potent enzymatic activity. UFL1 is an E3 ligase that localizes to both the nucleus and cytoplasm. Expression pattern analyses revealed that UFL1 is strongly upregulated during embryogenesis and progressively accumulates throughout seed maturation. Phenotypic analyses showed that UFL1 overexpression enhances seed dormancy, increases plant sensitivity to abscisic acid (ABA), and significantly delays seed germination and cotyledon greening, identifying UFL1 as a previously unrecognized positive regulator of ABA signaling. Biochemical analyses further demonstrated that UFL1 physically interacts with the bZIP transcription factor ABI5 and mediates its UFMylation, thereby antagonizing ubiquitination and stabilizing ABI5 protein abundance. Genetic evidence further supported that ABI5 acts downstream of UFL1 to regulate seed developmental processes. Collectively, our findings reveal UFMylation as a pivotal regulatory layer in plants and uncover a UFL1-ABI5 signaling module that coordinates seed maturation, dormancy, and germination.

如何引用

Molecular plant 的其他文献

• 植物非生物胁迫感知：生物化学和生物物理学基础。