具有非规范整合结构域(NLR-ID)的核苷酸结合富含亮氨酸重复序列(LRR)受体(NLR)广泛存在于植物基因组中。锌指BED(以果蝇蛋白边界元素相关因子和DNA复制相关元素结合因子命名,以下命名为BED)是最常见的ID之一。已表征了五种赋予细菌和真菌病原体抗性的BED-NLR。然而,BED-NLR是否以类似于其他NLR-ID的方式起作用是未知的。这里,我们使用小麦的染色体水平组装来探索Yr7和Yr5a基因组区域,与已知的NLR-ID基因座不同,没有证据表明他们附近有NLR合作伙伴。使用邻居网络分析,我们观察到,来自BED-NLRs的BED结构域与来自单BED蛋白的BED结构域和来自包含在转座酶中保守的结构域的含BED蛋白的BED结构域具有更多的相似性.我们在Yr7,Yr5和其他表征的BED-NLR中鉴定了核定位信号(NLS)。因此,我们提出这是赋予植物病原体抗性的BED-NLR的特征。我们表明,当在N.benthamiana中表达时,NLS在Yr7蛋白的截短版本中具有功能。我们没有观察到Yr7全长过表达时的细胞死亡,截断,和N.benthamiana的“MHD”变体。这表明该系统不适合研究BED-NLR信号传导或BED-NLR需要额外的组分来触发细胞死亡。这些结果为进一步理解BED结构域在BED-NLR介导的抗性中的作用定义了新的未来方向。
Nucleotide-binding leucine-rich-repeat (LRR) receptors (NLRs) with non-canonical integrated domains (NLR-IDs) are widespread in plant genomes. Zinc-finger BED (named after the Drosophila proteins Boundary Element-Associated Factor and DNA Replication-related Element binding Factor, named BED hereafter) are among the most frequently found IDs. Five BED-NLRs conferring resistance against bacterial and fungal pathogens have been characterized. However, it is unknown whether BED-NLRs function in a manner similar to other NLR-IDs. Here, we used chromosome-level assemblies of wheat to explore the Yr7 and Yr5a genomic regions and show that, unlike known NLR-ID loci, there is no evidence for a NLR-partner in their vicinity. Using neighbor-network analyses, we observed that BED domains from BED-NLRs share more similarities with BED domains from single-BED proteins and from BED-containing proteins harboring domains that are conserved in transposases. We identified a nuclear localization signal (NLS) in Yr7, Yr5, and the other characterized BED-NLRs. We thus propose that this is a feature of BED-NLRs that confer resistance to plant pathogens. We show that the NLS was functional in truncated versions of the Yr7 protein when expressed in N. benthamiana. We did not observe cell-death upon the overexpression of Yr7 full-length, truncated, and \'MHD\' variants in N. benthamiana. This suggests that either this system is not suitable to study BED-NLR signaling or that BED-NLRs require additional components to trigger cell death. These results define novel future directions to further understand the role of BED domains in BED-NLR mediated resistance.