Tameling Wladimir I L, Baulcombe David C
Sainsbury Laboratory, John Ines Centre, Norwich NR4 7UH, United Kingdom.
Plant Cell. 2007 May;19(5):1682-94. doi: 10.1105/tpc.107.050880. Epub 2007 May 25.
Nucleotide binding leucine-rich repeat (NB-LRR) proteins play an important role in plant and mammalian innate immunity. In plants, these resistance proteins recognize specific pathogen-derived effector proteins. Recognition subsequently triggers a rapid and efficient defense response often associated with the hypersensitive response and other poorly understood processes that suppress the pathogen. To investigate mechanisms associated with the activation of disease resistance responses, we investigated proteins binding to the potato (Solanum tuberosum) NB-LRR protein Rx that confers extreme resistance to Potato virus X (PVX) in potato and Nicotiana benthamiana. By affinity purification experiments, we identified an endogenous N. benthamiana Ran GTPase-Activating Protein2 (RanGAP2) as an Rx-associated protein in vivo. Further characterization confirmed the specificity of this interaction and showed that the association occurs through their N-terminal domains. By specific virus-induced gene silencing of RanGAP2 in N. benthamiana carrying Rx, we demonstrated that this interaction is required for extreme resistance to PVX and suggest that RanGAP2 is part of the Rx signaling complex. These results implicate RanGAP-mediated cellular mechanisms, including nucleocytoplasmic trafficking, in the activation of disease resistance.
核苷酸结合富含亮氨酸重复序列（NB-LRR）蛋白在植物和哺乳动物的天然免疫中发挥重要作用。在植物中，这些抗性蛋白识别特定病原体衍生的效应蛋白。识别随后触发快速有效的防御反应，该反应通常与超敏反应以及其他抑制病原体的了解较少的过程相关。为了研究与抗病反应激活相关的机制，我们研究了与马铃薯（Solanum tuberosum）NB-LRR蛋白Rx结合的蛋白，该蛋白赋予马铃薯和本氏烟草对马铃薯X病毒（PVX）的极端抗性。通过亲和纯化实验，我们在体内鉴定出一种内源性本氏烟草Ran鸟苷三磷酸酶激活蛋白2（RanGAP2）作为与Rx相关的蛋白。进一步的表征证实了这种相互作用的特异性，并表明这种关联通过它们的N末端结构域发生。通过对携带Rx的本氏烟草中RanGAP2进行特异性病毒诱导的基因沉默，我们证明这种相互作用是对PVX极端抗性所必需的，并表明RanGAP2是Rx信号复合物的一部分。这些结果表明RanGAP介导的细胞机制（包括核质运输）参与了抗病反应的激活。
