Department of Systems Biology, Division of Life Science, Yonsei University, Seoul, 03722, Korea.
Institute of Life Science and Biotechnology, Yonsei University, Seoul, 03722, Korea.
Planta. 2020 Oct 26;252(5):93. doi: 10.1007/s00425-020-03500-4.
AtKPNB1, an Arabidopsis importin-β protein, was regulated by AtAIRP1 E3 ubiquitin ligase, which intensified the ABA-mediated drought stress response. As an early step in the abscisic acid (ABA)-mediated drought response, the ABA signal is transduced into the nucleus, and thus the nuclear transport system is crucially involved in the drought stress response. AtKPNB1, an importin-β protein, which is a core component of nuclear transport, was previously reported to be a negative factor in the ABA-mediated drought stress response (Luo et al. Luo et al., Plant J 75:377-389, 2013). Here, we report that AtAIPR1, an Arabidopsis RING-type E3 ubiquitin (Ub) ligase, interacted with and ubiquitinated AtKPNB1. A null mutation of AtKPNB1 suppressed the ABA-insensitive germination phenotype of atairp1 mutant seedlings as compared to that of the wild-type plants. Furthermore, the ABA-insensitive stomatal closure and drought-susceptible phenotypes of atairp1 were rescued in atairp1atkpnb1 double mutant progeny, indicating that AtKPNB1 functions downstream of AtAIRP1. These data suggest that AtAIRP1 regulates the ABA-mediated drought response in Arabidopsis via ubiquitination of AtKPNB1.
AtKPNB1，一种拟南芥的导入素-β 蛋白，受 AtAIRP1 E3 泛素连接酶的调控，增强了 ABA 介导的干旱胁迫反应。作为 ABA 介导的干旱胁迫反应的早期步骤，ABA 信号被转导到细胞核中，因此核转运系统在干旱胁迫反应中起着至关重要的作用。AtKPNB1，一种导入素-β 蛋白，是核转运的核心组成部分，先前被报道为 ABA 介导的干旱胁迫反应的负因子（Luo 等人，植物 J 75:377-389，2013）。在这里，我们报告说，AtAIPR1，一种拟南芥 RING 型 E3 泛素（Ub）连接酶，与 AtKPNB1 相互作用并泛素化 AtKPNB1。AtKPNB1 的缺失突变抑制了 atairp1 突变体幼苗对 ABA 不敏感的萌发表型，与野生型植物相比。此外，atairp1 的 ABA 不敏感的气孔关闭和耐旱表型在 atairp1atkpnb1 双突变体后代中得到挽救，表明 AtKPNB1 是 AtAIRP1 的下游作用因子。这些数据表明，AtAIRP1 通过泛素化 AtKPNB1 调节拟南芥中 ABA 介导的干旱胁迫反应。
