Arabidopsis PLANT U-BOX44 down-regulates osmotic stress signaling by mediating Ca2+-DEPENDENT PROTEIN KINASE4 degradation
Arabidopsis PLANT U-BOX44 down-regulates osmotic stress signaling by mediating Ca2+-DEPENDENT PROTEIN KINASE4 degradation
复制标题
拟南芥U-BOX44通过介导钙依赖蛋白KINASE 4降解下调渗透胁迫信号
DOI：
10.1093/plcell/koad173
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发表时间：
2023-07-07
期刊：
影响因子：
11.6
通讯作者：
Li, Zixing
中科院分区：
文献类型：
--
作者：
Fan, Wei;Liao, Xiliang;Li, Zixing
渗透胁迫下调植物U-BOX 44介导的钙依赖蛋白激酶4（Ca 2 +-dependentproteinkinases，CPKs）的降解，诱导CPK 4的积累，CPKs是植物对渗透胁迫等多种环境胁迫应答的重要调节因子。CPK通过由渗透压应激触发的细胞内Ca 2+水平的增加而被激活。然而，活性CPK蛋白的水平如何动态和精确地调节尚未确定。在这里，我们表明，NaCl/甘露醇诱导的渗透胁迫促进CPK 4蛋白的积累，通过破坏其26 S蛋白酶体介导的CPK 4降解拟南芥（拟南芥）。我们分离了PLANT U-BOX 44（PUB 44），一种U-box型E3泛素连接酶，可泛素化CPK 4并引发其降解。无钙或无激酶活性的CPK 4变体与Ca 2+结合的活性形式的CPK 4相比优先降解。此外，PUB 44在植物对渗透胁迫的响应中表现出依赖于CPK 4的负作用。渗透胁迫通过抑制PUB 44介导的CPK 4降解诱导CPK 4蛋白的积累。目前的研究结果揭示了调节CPK蛋白水平的机制，并建立PUB 44依赖的CPK 4调节在调节植物渗透胁迫响应的相关性，提供渗透胁迫信号转导机制的见解。
Osmotic stress down-regulates PLANT U-BOX44-mediated degradation of Ca2+-DEPENDENT PROTEIN KINASE4 to induce CPK4 accumulation.Calcium (Ca2+)-dependent protein kinases (CPKs) are essential regulators of plant responses to diverse environmental stressors, including osmotic stress. CPKs are activated by an increase in intracellular Ca2+ levels triggered by osmotic stress. However, how the levels of active CPK protein are dynamically and precisely regulated has yet to be determined. Here, we demonstrate that NaCl/mannitol-induced osmotic stress promoted the accumulation of CPK4 protein by disrupting its 26S proteasome-mediated CPK4 degradation in Arabidopsis (Arabidopsis thaliana). We isolated PLANT U-BOX44 (PUB44), a U-box type E3 ubiquitin ligase that ubiquitinates CPK4 and triggers its degradation. A calcium-free or kinase-inactive CPK4 variant was preferentially degraded compared to the Ca2+-bound active form of CPK4. Furthermore, PUB44 exhibited a CPK4-dependent negative role in the response of plants to osmotic stress. Osmotic stress induced the accumulation of CPK4 protein by inhibiting PUB44-mediated CPK4 degradation. The present findings reveal a mechanism for regulating CPK protein levels and establish the relevance of PUB44-dependent CPK4 regulation in modulating plant osmotic stress responses, providing insights into osmotic stress signal transduction mechanisms.