Plant NLR proteins enable the immune system to recognize and respond to pathogen attack. An early consequence of immune activation is transcriptional reprogramming. Some NLRs have been shown to act in the nucleus and interact with transcription factors. The Rx1 NLR protein of potato binds and distorts double-stranded DNA. However, the components of the chromatin-localized Rx1 complex are largely unknown. Here, we report a physical and functional interaction between Rx1 and NbDBCP, a bromodomain-containing chromatin-interacting protein. NbDBCP accumulates in the nucleoplasm and nucleolus, interacts with chromatin, and redistributes Rx1 to the nucleolus in a subpopulation of imaged cells. Rx1 overexpression reduces the interaction between NbDBCP and chromatin. NbDBCP is a negative regulator of Rx1-mediated immune responses to potato virus X (PVX), and this activity requires an intact bromodomain. Previously, Rx1 has been shown to regulate the DNA-binding activity of a Golden2-like transcription factor, NbGlk1. Rx1 and NbDBCP act synergistically to reduce NbGlk1 DNA binding, suggesting a mode of action for NbDBCP’s inhibitory effect on immunity. This study provides new mechanistic insight into the mechanism by which a chromatin-localized NLR complex co-ordinates immune signaling after pathogen perception.

植物 NLR 蛋白使免疫系统能够识别病原体攻击并做出反应。免疫激活的早期后果是转录重编程。一些 NLR 已被证明在细胞核中发挥作用并与转录因子相互作用。马铃薯的 Rx1 NLR 蛋白结合并扭曲双链 DNA。然而，染色质定位的 Rx1 复合物的成分很大程度上未知。在这里，我们报告了 Rx1 和Nb DBCP（一种含溴结构域的染色质相互作用蛋白）之间的物理和功能相互作用。 Nb DBCP 在核质和核仁中积累，与染色质相互作用，并将 Rx1 重新分配到成像细胞亚群中的核仁。 Rx1 过表达会减少Nb DBCP 与染色质之间的相互作用。 Nb DBCP 是 Rx1 介导的马铃薯病毒 X (PVX) 免疫反应的负调节因子，这种活性需要完整的溴结构域。此前，Rx1 已被证明可以调节 Golden2 样转录因子Nb Glk1 的 DNA 结合活性。 Rx1 和Nb DBCP 协同作用，减少Nb Glk1 DNA 结合，表明Nb DBCP 对免疫的抑制作用的一种作用模式。这项研究为染色质定位的 NLR 复合物在病原体感知后协调免疫信号传导的机制提供了新的机制见解。