The Plant Noncanonical Antiviral Resistance Protein JAX1 Inhibits Potexviral Replication by Targeting the Viral RNA-Dependent RNA Polymerase
The Plant Noncanonical Antiviral Resistance Protein JAX1 Inhibits Potexviral Replication by Targeting the Viral RNA-Dependent RNA Polymerase
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DOI：
10.1128/jvi.01506-18
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发表时间：
2018-11
影响因子：
5.4
通讯作者：
Tetsuya Yoshida;Takuya Shiraishi;Yuka Hagiwara-Komoda;K. Komatsu;K. Maejima;Yukari Okano;Yuji Fujimoto;Akira Yusa;Y. Yamaji;S. Namba
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文献类型：
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作者：
Tetsuya Yoshida;Takuya Shiraishi;Yuka Hagiwara-Komoda;K. Komatsu;K. Maejima;Yukari Okano;Yuji Fujimoto;Akira Yusa;Y. Yamaji;S. Namba
抗性基因在植物抗病毒天然免疫中起着至关重要的作用。传统的核苷酸结合富含亮氨酸重复序列（NLR）蛋白的作用和相关的防御途径已经研究了很长时间。相反，最近发现的不编码NLR蛋白的抗性基因（非NLR抗性基因）尚未得到广泛研究。在这里，我们报告说，非NLR抗性因子JAX 1，一个独特的jacalin型凝集素蛋白，抑制从头马铃薯X病毒RNA的合成，针对病毒复制酶的巨大复杂。这与其他已知的抗病毒耐药机制不同。对凝集素型蛋白介导的抗病毒免疫中靶点的分子阐明将增强我们对非NLR介导的植物抗性系统的理解。摘要了解植物的天然免疫机制是抗病育种的基础。以前，我们确定了抗病毒抗性基因JAX 1从拟南芥，抑制马铃薯X病毒感染。JAX 1编码一种独特的jacalin型凝集素蛋白。在这项研究中，我们分析了JAX 1介导的抗性的分子机制。JAX 1限制了缺乏运动相关蛋白的马铃薯X病毒复制子的增殖，表明抑制病毒复制。因此，我们开发了一种体外马铃薯X病毒（PVX）的翻译/复制系统，使用烟草原生质体的无液泡和无核裂解液，我们发现JAX 1抑制病毒RNA的合成，但不翻译的病毒RNA依赖的RNA聚合酶（RdRp）。JAX 1不影响PVX抗性破坏突变体的复制。通过蔗糖梯度沉降分离的组分的蓝色非变性聚丙烯酰胺凝胶电泳显示，PVX RdRp构成了似乎对病毒复制至关重要的高分子量复合物。JAX 1在野生型PVX复制子的复合物中检测到，但在抗性破坏突变体中未检测到。此外，JAX 1与野生型病毒的RdRp相互作用，但不与在耐药性破坏残基处具有点突变的病毒的RdRp相互作用。这些结果表明JAX 1靶向RdRp以抑制马铃薯X病毒复制。重要性抗性基因在植物抗病毒天然免疫中起着至关重要的作用。传统的核苷酸结合富含亮氨酸重复序列（NLR）蛋白的作用和相关的防御途径已经研究了很长时间。相反，最近发现的不编码NLR蛋白的抗性基因（非NLR抗性基因）尚未得到广泛研究。在这里，我们报告说，非NLR抗性因子JAX 1，一个独特的jacalin型凝集素蛋白，抑制从头马铃薯X病毒RNA的合成，针对病毒复制酶的巨大复杂。这与其他已知的抗病毒耐药机制不同。对凝集素型蛋白介导的抗病毒免疫中靶点的分子阐明将增强我们对非NLR介导的植物抗性系统的理解。
Resistance genes play a crucial role in plant antiviral innate immunity. The roles of conventional nucleotide-binding leucine-rich repeat (NLR) proteins and the associated defense pathways have long been studied. In contrast, recently discovered resistance genes that do not encode NLR proteins (non-NLR resistance genes) have not been investigated extensively. Here we report that the non-NLR resistance factor JAX1, a unique jacalin-type lectin protein, inhibits de novo potexviral RNA synthesis by targeting the huge complex of viral replicase. This is unlike other known antiviral resistance mechanisms. Molecular elucidation of the target in lectin-type protein-mediated antiviral immunity will enhance our understanding of the non-NLR-mediated plant resistance system. ABSTRACT Understanding the innate immune mechanisms of plants is necessary for the breeding of disease-resistant lines. Previously, we identified the antiviral resistance gene JAX1 from Arabidopsis thaliana, which inhibits infection by potexviruses. JAX1 encodes a unique jacalin-type lectin protein. In this study, we analyzed the molecular mechanisms of JAX1-mediated resistance. JAX1 restricted the multiplication of a potexviral replicon lacking movement-associated proteins, suggesting inhibition of viral replication. Therefore, we developed an in vitro potato virus X (PVX) translation/replication system using vacuole- and nucleus-free lysates from tobacco protoplasts, and we revealed that JAX1 inhibits viral RNA synthesis but not the translation of the viral RNA-dependent RNA polymerase (RdRp). JAX1 did not affect the replication of a resistance-breaking mutant of PVX. Blue native polyacrylamide gel electrophoresis of fractions separated by sucrose gradient sedimentation showed that PVX RdRp constituted the high-molecular-weight complex that seems to be crucial for viral replication. JAX1 was detected in this complex of the wild-type PVX replicon but not in that of the resistance-breaking mutant. In addition, JAX1 interacted with the RdRp of the wild-type virus but not with that of a virus with a point mutation at the resistance-breaking residue. These results suggest that JAX1 targets RdRp to inhibit potexviral replication. IMPORTANCE Resistance genes play a crucial role in plant antiviral innate immunity. The roles of conventional nucleotide-binding leucine-rich repeat (NLR) proteins and the associated defense pathways have long been studied. In contrast, recently discovered resistance genes that do not encode NLR proteins (non-NLR resistance genes) have not been investigated extensively. Here we report that the non-NLR resistance factor JAX1, a unique jacalin-type lectin protein, inhibits de novo potexviral RNA synthesis by targeting the huge complex of viral replicase. This is unlike other known antiviral resistance mechanisms. Molecular elucidation of the target in lectin-type protein-mediated antiviral immunity will enhance our understanding of the non-NLR-mediated plant resistance system.