Tsinghua-Peking Joint Center for Life Sciences, and MOE Key Laboratory of Bioinformatics, School of Life Sciences, Tsinghua University, Beijing 100084, China.
Department of Microbiology and Plant Pathology, University of California, Riverside, CA 92521, USA.
J Genet Genomics. 2018 Jan 20;45(1):33-40. doi: 10.1016/j.jgg.2017.11.005. Epub 2017 Dec 24.
Viruses can infect host plants to cause severe diseases and substantial agricultural loss, while plants have evolved RNA interference (RNAi) strategy to defend against viral infection. Despite enormous efforts, only a few host proteins in RNAi pathway were shown to mediate antiviral defense, including RNA-dependent RNA polymerase 1 (RDR1), RDR6, DICER-LIKE 2 (DCL2) and DCL4. In this study, we carried out a genetic screen for antiviral factors of RNAi pathway in Arabidopsis rdr6 background via inoculation with a 2b-deficient Cucumber Mosaic Virus (CMV-Δ2b). We identified a mutant susceptible to CMV-Δ2b, referred to as enhancer of rdr6 (enor) 3-1 rdr6, and found that ENOR3 encodes a functionally unknown protein with high homology to the mammalian Non Imprinted in Prader-Willi/Angelman (NIPA) magnesium transporters. ENOR3 inhibits accumulation of CMV-Δ2b and acts additively with RDR1, RDR6, DCL2 and DCL4 in antiviral defense. These results uncover that ENOR3 is a key component in antiviral RNAi pathway, and provide new insights into antiviral immunity.
病毒可以感染宿主植物，导致严重疾病和大量农业损失，而植物已经进化出 RNA 干扰 (RNAi) 策略来抵御病毒感染。尽管付出了巨大的努力，但只有少数 RNAi 途径中的宿主蛋白被证明介导抗病毒防御，包括 RNA 依赖性 RNA 聚合酶 1 (RDR1)、RDR6、DICER-LIKE 2 (DCL2) 和 DCL4。在这项研究中，我们通过用 2b 缺失的黄瓜花叶病毒 (CMV-Δ2b) 接种拟南芥 rdr6 背景，进行了 RNAi 途径抗病毒因子的遗传筛选。我们鉴定了一个对 CMV-Δ2b 敏感的突变体，称为 rdr6 的增强子(enor) 3-1 rdr6，并发现 ENOR3 编码一种具有高度同源性的功能未知蛋白哺乳动物非印记性 Prader-Willi/Angelman (NIPA) 镁转运体。ENOR3 抑制 CMV-Δ2b 的积累，并与 RDR1、RDR6、DCL2 和 DCL4 一起在抗病毒防御中起累加作用。这些结果揭示了 ENOR3 是抗病毒 RNAi 途径中的关键组成部分，并为抗病毒免疫提供了新的见解。
