Nucleotide-binding site and leucine-rich repeat receptors (NLRs) play pivotal roles in plant immunity. The regulation of NLR stability is essential to ensure effective immunity, whereas the exact mechanism is largely unclear. The Arabidopsis CC-NBS-LRR protein L5 (At1g12290) can induce cell death in Nicotiana benthamiana, but not in Arabidopsis thaliana. We screened the interactors of L5 by yeast two-hybrid, and found that the BOI can interact with the CC domain of L5. Transiently expressed BOI reduced the protein level of L5, and suppressed the auoactivity of L5 in N. benthamiana. BOI can interact and ubiquitinate L5 in vitro, and mediate the proteasomal degradation of L5 in N. benthamiana and Arabidopsis. The Lys425 in the NBS domain of L5 is the critical unbiquitin site for the degradation. In conclusion, our results reveal a mechanism for the control of the stability of L5 protein and for the suppressed of L5-triggered cell death by a RING-type E3 ligase through the ubiquitin proteasome system.

核苷酸结合位点和富含亮氨酸的重复受体 (NLR) 在植物免疫中起关键作用。NLR稳定性的调节对于确保有效免疫至关重要，而确切的机制尚不清楚。拟南芥CC-NBS-LRR 蛋白 L5 (At1g12290) 可以在本氏烟草中诱导细胞死亡，但在拟南芥中则不能。我们通过酵母双杂交筛选了L5的相互作用子，发现BOI可以与L5的CC结构域相互作用。瞬时表达的BOI降低了本氏烟草中L5的蛋白水平，并抑制了L5的自体活性。BOI可以在体外与L5相互作用并泛素化，介导本氏烟中L5的蛋白酶体降解。和拟南芥。L5 的 NBS 结构域中的 Lys425 是降解的关键非泛素位点。总之，我们的结果揭示了一种控制 L5 蛋白稳定性和通过泛素蛋白酶体系统通过环型 E3 连接酶抑制 L5 触发的细胞死亡的机制。