PDF(Pubmed)
Abstract：
Nucleotide-binding and leucine-rich repeat receptors (NLRs) are the most important and largest class of immune receptors in plants. The Pi36 gene encodes a canonical CC-NBS-LRR protein that confers resistance to rice blast fungal infections. Here, we show that the CC domain of Pi36 plays a role in cell death induction. Furthermore, self-association is required for the CC domain-mediated cell death, and the self-association ability is correlated with the cell death level. In addition, the NB-ARC domain may suppress the activity of the CC domain through intramolecular interaction. The mutations D440G next to the RNBS-D motif and D503V in the MHD motif autoactivated Pi36, but the mutation K212 in the P-loop motif inhibited this autoactivation, indicating that nucleotide binding of the NB-ARC domain is essential for Pi36 activation. We also found that the LRR domain is required for D503V- and D440G-mediated Pi36 autoactivation. Interestingly, several mutations in the CC domain compromised the CC domain-mediated cell death without affecting the D440G- or D503V-mediated Pi36 autoactivation. The autoactivate Pi36 variants exhibited stronger self-associations than the inactive variants. Taken together, we speculated that the CC domain of Pi36 executes cell death activities, whereas the NB-ARC domain suppressed CC-mediated cell death via intermolecular interaction. The NB-ARC domain releases its suppression of the CC domain and strengthens the self-association of Pi36 to support the CC domain, possibly through nucleotide exchange.
摘要：
核苷酸结合和富含亮氨酸的重复受体（NLR）是植物中最重要和最大的一类免疫受体。Pi36基因编码一种典型的CC-NBS-LRR蛋白，该蛋白赋予对稻瘟病真菌感染的抗性。这里,我们显示Pi36的CC结构域在细胞死亡诱导中起作用。此外，自缔合是CC域介导的细胞死亡所必需的，自缔合能力与细胞死亡水平相关。此外,NB-ARC结构域可以通过分子内相互作用抑制CC结构域的活性。MHD基序中RNBS-D基序旁边的突变D440G和D503V自动激活Pi36，但P环基序中的突变K212抑制了这种自动激活，表明NB-ARC结构域的核苷酸结合对于Pi36激活是必需的。我们还发现LRR结构域是D503V-和D440G-介导的Pi36自激活所必需的。有趣的是,CC结构域中的一些突变损害了CC结构域介导的细胞死亡,而不影响D440G或D503V介导的Pi36自激活.自激活Pi36变体表现出比非活性变体更强的自缔合。一起来看,我们推测Pi36的CC域执行细胞死亡活动，而NB-ARC结构域通过分子间相互作用抑制CC介导的细胞死亡。NB-ARC域释放其对CC域的抑制，并加强Pi36的自关联以支持CC域，可能是通过核苷酸交换.
