Protein degradation by the ubiquitin/26S proteasome system is a critical process that modulates many eukaryotic cellular processes. E3 ligase usually modulates stress response by adjusting the stability of transcription factors. Previous studies have shown that a RING‐type E3 ligase, CaASRF1, positively modulates abscisic acid (ABA) signalling and ABA‐mediated drought response by modulating the stability of CaAIBZ1 and CaATBZ1. In this study, we conducted yeast two‐hybrid (Y2H) screening with CaATBZ1 to isolate an additional modulator, identified as CaATIR1 (Capsicum annuum ATBZ1 Interacting RING finger protein 1). CaATIR1 has E3 ligase activity and promoted CaATBZ1 degradation using the 26S proteasome system. We investigated the loss‐of and gain‐of functions of this E3 ligase by using silencing pepper and overexpressing (OX) Arabidopsis plants, respectively. In response to ABA and drought treatments, CaATIR1 ‐silenced pepper plants showed ABA insensitive and drought‐sensitive phenotypes, while CaATIR1 ‐OX plants showed the opposite phenotypes. Additionally, CaATBZ1 ‐silencing rescued the ABA insensitive and drought‐sensitive phenotypes of CaATIR1 ‐silencing pepper plants. Taken together, these data demonstrate that the stability of CaATBZ1 mediated by CaATIR1 has a crucial role in drought stress signalling in pepper plants.

中文翻译：

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辣椒环型 E3 连接酶 CaATIR1 通过调节 CaATBZ1 的稳定性来正向调节脱落酸信号传导和干旱响应。


泛素/26S 蛋白酶体系统的蛋白质降解是调节许多真核细胞过程的关键过程。 E3连接酶通常通过调节转录因子的稳定性来调节应激反应。先前的研究表明，RING 型 E3 连接酶 CaASRF1 通过调节 CaAIBZ1 和 CaATBZ1 的稳定性，正向调节脱落酸 (ABA) 信号传导和 ABA 介导的干旱反应。在这项研究中，我们用 CaATBZ1 进行了酵母双杂交 (Y2H) 筛选，以分离出一种额外的调节剂，鉴定为 CaATIR1（ C apsicum a nnuum AT BZ1 I nteracting R ING Finger Protein 1 ）。 CaATIR1 具有 E3 连接酶活性，并使用 26S 蛋白酶体系统促进 CaATBZ1 降解。我们分别使用沉默辣椒和过表达 (OX) 拟南芥植物研究了该 E3 连接酶功能的丧失和获得。为了响应 ABA 和干旱处理， CaATIR1沉默的辣椒植物表现出 ABA 不敏感和干旱敏感的表型，而CaATIR1 OX 植物则表现出相反的表型。此外， CaATBZ1沉默挽救了CaATIR1沉默辣椒植物的 ABA 不敏感和干旱敏感表型。综上所述，这些数据表明 CaATIR1 介导的 CaATBZ1 的稳定性在辣椒植物的干旱胁迫信号传导中具有至关重要的作用。