Cucumber mosaic virus coat protein modulates the accumulation of 2b protein and antiviral silencing that causes symptom recovery in planta.
Cucumber mosaic virus coat protein modulates the accumulation of 2b protein and antiviral silencing that causes symptom recovery in planta.
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黄瓜花叶病毒外壳蛋白调节 2b 蛋白的积累和抗病毒沉默，导致植物症状恢复
DOI：
10.1371/journal.ppat.1006522
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发表时间：
2017-07
期刊：
影响因子：
6.7
通讯作者：
Wang XB
中科院分区：
文献类型：
--
作者：
Zhang XP;Liu DS;Yan T;Fang XD;Dong K;Xu J;Wang Y;Yu JL;Wang XB
茎尖分生组织（SAM）由于RNA沉默而对大多数植物病毒具有抗性，RNA沉默的病毒抑制子（VSRs）抑制SAM以促进SAM的瞬时病毒入侵。在许多情况下，会出现慢性症状和长期病毒恢复，但对潜在的机制知之甚少。在这里，我们发现，野生型黄瓜花叶病毒（CMVWT）入侵SAM短暂，但随后从分生组织中消除。出乎意料的是，一个CMV突变体，命名为CMVRA，它在外壳蛋白（CP）的N-末端富含丙氨酸的区域中含有丙氨酸取代，持续侵入SAM，并导致顶端优势明显减少。值得注意的是，CMVWT病毒在感染植物的新出现的叶子中引起比CMVRA更有效的抗病毒沉默。然而，这两种病毒在缺乏宿主RNA依赖性RNA聚合酶6（RDR 6）或基因沉默3（SGS 3）的拟南芥突变体中引起严重的症状和最小的抗病毒沉默效应，表明CMVWT诱导宿主RDR 6/SGS 3依赖性抗病毒沉默。我们还表明，在CMVWT感染中引起2b蛋白的积累减少，从而挽救了有效的抗病毒RNA沉默。事实上，共浸润试验表明，抑制转录后基因沉默介导的2b是更严重的损害CPWT的共表达比CPRA。我们进一步证明了CPWT具有高的RNA结合活性，导致小麦胚芽系统中的翻译抑制，并且CPWT在体内与SGS 3结合成点状颗粒。因此，我们认为CPWT结合和保护的RNA可能作为RDR 6/SGS 3复合物的模板用于siRNA扩增。总之，这些发现表明CMV CP作为调节抗病毒沉默和VSR活性的中心枢纽，并介导病毒自我减毒和长期症状恢复。
Shoot apical meristems (SAM) are resistant to most plant viruses due to RNA silencing, which is restrained by viral suppressors of RNA silencing (VSRs) to facilitate transient viral invasion of the SAM. In many cases chronic symptoms and long-term virus recovery occur, but the underlying mechanisms are poorly understood. Here, we found that wild-type Cucumber mosaic virus (CMVWT) invaded the SAM transiently, but was subsequently eliminated from the meristems. Unexpectedly, a CMV mutant, designated CMVRA that harbors an alanine substitution in the N-terminal arginine-rich region of the coat protein (CP) persistently invaded the SAM and resulted in visible reductions in apical dominance. Notably, the CMVWT virus elicited more potent antiviral silencing than CMVRA in newly emerging leaves of infected plants. However, both viruses caused severe symptoms with minimal antiviral silencing effects in the Arabidopsis mutants lacking host RNA-DEPENDENT RNA POLYMERASE 6 (RDR6) or SUPPRESSOR OF GENE SILENCING 3 (SGS3), indicating that CMVWT induced host RDR6/SGS3-dependent antiviral silencing. We also showed that reduced accumulation of the 2b protein is elicited in the CMVWT infection and consequently rescues potent antiviral RNA silencing. Indeed, co-infiltration assays showed that the suppression of posttranscriptional gene silencing mediated by 2b is more severely compromised by co-expression of CPWT than by CPRA. We further demonstrated that CPWT had high RNA binding activity leading to translation inhibition in wheat germ systems, and CPWT was associated with SGS3 into punctate granules in vivo. Thus, we propose that the RNAs bound and protected by CPWT possibly serve as templates of RDR6/SGS3 complexes for siRNA amplification. Together, these findings suggest that the CMV CP acts as a central hub that modulates antiviral silencing and VSRs activity, and mediates viral self-attenuation and long-term symptom recovery.
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影响因子：
4.8
作者：
Boni, S;Lavergne, JP;Cahour, A
通讯作者：
Cahour, A
影响因子：
7.4
作者：
Dun, Elizabeth Ann;Ferguson, Brett James;Beveridge, Christine Anne
通讯作者：
Beveridge, Christine Anne
影响因子：
11.6
作者：
Diaz-Pendon, Juan A.;Li, Feng;Ding, Shou-Wei
通讯作者：
Ding, Shou-Wei
黄瓜花叶病毒 2b N 末端附近的两个氨基酸在抑制 RNA 沉默和病毒感染性中发挥着关键作用。
影响因子：
4.9
作者：
Dong, Kai;Wang, Ying;Wang, Xian-Bing
通讯作者：
Wang, Xian-Bing
影响因子：
3.7
作者：
Annamalai, P;Rao, ALN
通讯作者：
Rao, ALN