The Arabidopsis Leucine-Rich Repeat Receptor Kinase BIR3 Negatively Regulates BAK1 Receptor Complex Formation and Stabilizes BAK1
The Arabidopsis Leucine-Rich Repeat Receptor Kinase BIR3 Negatively Regulates BAK1 Receptor Complex Formation and Stabilizes BAK1
复制标题
拟南芥富含亮氨酸的重复受体激酶 BIR3 负向调节 BAK1 受体复合物的形成并稳定 BAK1
DOI：
10.1105/tpc.17.00376
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发表时间：
2017-09-01
期刊：
影响因子：
11.6
通讯作者：
Kemmerling, Birgit
中科院分区：
文献类型：
--
作者：
Imkampe, Julia;Halter, Thierry;Kemmerling, Birgit
受体激酶BIR 3负调节细胞表面受体复合物，从而防止不必要的免疫和激素反应激活。BAK 1是多配体结合富亮氨酸重复序列受体激酶（LRR-RKs）的辅助受体和正调节因子，并参与油菜素类固醇（BR）依赖性生长和发育、先天免疫和细胞死亡控制。BAK 1相互作用的LRR-RKs BIR 2和BIR 3先前通过体内BAK 1复合物的蛋白质组学分析鉴定。在这里，我们表明，BAK 1相关的途径，如先天免疫和细胞死亡控制的影响BIR 3在拟南芥。BIR 3也对BR信号传导具有强烈的负面影响。BIR 3直接与BR受体BRI 1和其他配体结合受体相互作用，并通过竞争性抑制BRI 1来负调节BR信号传导。BIR 3在配体暴露后从BAK 1和BRI 1释放，并直接影响BAK 1与BRI 1或鞭毛蛋白传感2复合物的形成。bak 1和bir 3的双突变体表现出自发的细胞死亡和防御反应的组成性激活。BAK 1及其最接近的同源物BKK 1与BIR 3相互作用并被BIR 3稳定，表明bak 1 bir 3双突变体通过BIR 3靶蛋白的去稳定化模拟在bak 1 bkk 1突变体中观察到的自发细胞死亡表型。我们的研究结果为BAK 1受体复合物的负调控机制提供了证据，其中BIR 3与BAK 1相互作用并抑制配体结合受体以防止BAK 1受体复合物的形成。
The receptor kinase BIR3 negatively regulates cell surface receptor complexes and thereby prevents unwanted activation of immune and hormone responses. BAK1 is a coreceptor and positive regulator of multiple ligand binding leucine-rich repeat receptor kinases (LRR-RKs) and is involved in brassinosteroid (BR)-dependent growth and development, innate immunity, and cell death control. The BAK1-interacting LRR-RKs BIR2 and BIR3 were previously identified by proteomics analyses of in vivo BAK1 complexes. Here, we show that BAK1-related pathways such as innate immunity and cell death control are affected by BIR3 in Arabidopsis thaliana. BIR3 also has a strong negative impact on BR signaling. BIR3 directly interacts with the BR receptor BRI1 and other ligand binding receptors and negatively regulates BR signaling by competitive inhibition of BRI1. BIR3 is released from BAK1 and BRI1 after ligand exposure and directly affects the formation of BAK1 complexes with BRI1 or FLAGELLIN SENSING2. Double mutants of bak1 and bir3 show spontaneous cell death and constitutive activation of defense responses. BAK1 and its closest homolog BKK1 interact with and are stabilized by BIR3, suggesting that bak1 bir3 double mutants mimic the spontaneous cell death phenotype observed in bak1 bkk1 mutants via destabilization of BIR3 target proteins. Our results provide evidence for a negative regulatory mechanism for BAK1 receptor complexes in which BIR3 interacts with BAK1 and inhibits ligand binding receptors to prevent BAK1 receptor complex formation.