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https://mp.weixin.qq.com/s/2TZsxdAszEPpTK_Eb4j6_g

近日，四川大学席德慧团队在Plant J发表了题为《NtG3BPL1 confers resistance to chilli veinal mottle virus through promoting the degradation of 6K2 in tobacco》的研究论文，揭示了NtG3BPL1通过促进对辣椒脉斑驳病毒6K2的降解赋予烟草对该病毒的抗性。

RNA调控网络是植物细胞中涉及mRNA修饰、翻译和降解的复杂而动态的调控。Ras-GAP SH3结构域结合蛋白（G3BP）是一种用于组装应激颗粒（SG）的支架蛋白，被认为是哺乳动物的抗病毒成分。然而，G3BP在植物感染病毒期间的功能在很大程度上仍然未知。

在本研究中，作者在烟草中鉴定了四个G3BP样蛋白（NtG3BPL）成员，并且在辣椒脉斑驳驳病毒（ChiVMV）感染过程中发现NtG3BPL1的表达水平上调。

NtG3BPL1定位在细胞核和细胞质中，在瞬时高温处理下形成细胞质颗粒，而在ChiVMV感染下细胞质颗粒的丰度降低。NtG3BPL1的过表达抑制了ChiVMV感染并延迟了症状的发作，而NtG3BPL1-敲除促进了ChiVM的感染。

此外，NtG3BPL1直接与ChiVMV 6K2蛋白相互作用，而6K2蛋白对NtG3BPL1-来源的细胞质颗粒没有影响。进一步的研究表明，NtG3BPL1的表达降低了6K2-GFP的叶绿体定位，并且NtG3BPL1-6K2相互作用复合物定位在细胞质中。进一步证据显示，NtG3BPL1通过自噬途径促进6K2的降解，6K2和ChiVMV在寄主植物中的积累受到自噬激活或抑制的影响。

总之，本研究的结果表明，NtG3BPL1在烟草对ChiVMV感染的抗性中起着正调控作用，揭示了植物G3BP在抗病毒策略中的新机制。

The RNA regulatory network is a complex and dynamic regulation in plant cells involved in mRNA modification, translation, and degradation. Ras-GAP SH3 domain-binding protein (G3BP) is a scaffold protein for the assembly of stress granules (SGs) and is considered an antiviral component in mammals. However, the function of G3BP during virus infection in plants is still largely unknown. In this study, four members of the G3BP-like proteins (NtG3BPLs) were identified in Nicotiana tabacum and the expression levels of NtG3BPL1 were upregulated during chilli veinal mottle virus (ChiVMV) infection. NtG3BPL1 was localized in the nucleus and cytoplasm, forming cytoplasmic granules under transient high-temperature treatment, whereas the abundance of cytoplasmic granules was decreased under ChiVMV infection. Overexpression of NtG3BPL1 inhibited ChiVMV infection and delayed the onset of symptoms, whereas knockout of NtG3BPL1 promoted ChiVMV infection. In addition, NtG3BPL1 directly interacted with ChiVMV 6K2 protein, whereas 6K2 protein had no effect on NtG3BPL1-derived cytoplasmic granules. Further studies revealed that the expression of NtG3BPL1 reduced the chloroplast localization of 6K2-GFP and the NtG3BPL1-6K2 interaction complex was localized in the cytoplasm. Furthermore, NtG3BPL1 promoted the degradation of 6K2 through autophagy pathway, and the accumulation of 6K2 and ChiVMV was affected by autophagy activation or inhibition in plants. Taken together, our results demonstrate that NtG3BPL1 plays a positive role in tobacco resistance against ChiVMV infection, revealing a novel mechanism of plant G3BP in antiviral strategy.

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