The brown planthopper (Nilaparvata lugens Stål, BPH) resistance gene BPH9 encodes an unusual coiled-coil (CC) nucleotide-binding leucine-rich repeat (LRR) protein with two nucleotide-binding site (NBS) domains. To understand how this CC–NBS–NBS–LRR (CNNL) protein regulates defense signaling and BPH resistance, we dissected each domain’s functions. The CC domain of BPH9 self-associated and was sufficient to induce cell death. The region of 97–115 residues in the CC domain is crucial for self-association and activation. NBS2, which contains a complete set of NBS function motifs and inhibits CC domain activation, rather than NBS1, acts as a molecular switch to regulate the activity of BPH9. We demonstrated that the CC domain, the NBS domain, and the LRR domain of BPH9 associate with each other and themselves in planta. Further domain swapping experiments revealed that the CC domains of BPH9 and susceptible alleles were similarly competent to induce resistance and the hypersensitive response, while the LRR domain of BPH9 confers resistance specificity to BPH. These findings provide new insights into the regulatory mechanisms governing the activity of CNNL proteins.

中文翻译：

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具有两个核苷酸结合位点结构域的褐飞虱抗性蛋白的分子和功能分析

褐飞虱 ( Nilaparvata lugens Stål, BPH) 抗性基因BPH9编码具有两个核苷酸结合位点 (NBS) 结构域的不寻常的卷曲螺旋 (CC) 核苷酸结合富含亮氨酸重复 (LRR) 蛋白。为了了解这种 CC-NBS-NBS-LRR (CNNL) 蛋白如何调节防御信号传导和 BPH 抗性，我们剖析了每个结构域的功能。BPH9 的 CC 结构域自相关并足以诱导细胞死亡。CC 结构域中 97-115 个残基的区域对于自缔合和激活至关重要。NBS2 包含一整套 NBS 功能基序并抑制 CC 域激活，而不是 NBS1，作为调节 BPH9 活性的分子开关。我们证明了 BPH9 的 CC 结构域、NBS 结构域和 LRR 结构域在足底相互关联并相互关联. 进一步的结构域交换实验表明，BPH9 和易感等位基因的 CC 结构域同样能够诱导抗性和过敏反应，而 BPH9 的 LRR 结构域赋予 BPH 抗性特异性。这些发现为控制 CNNL 蛋白活性的调节机制提供了新的见解。