The AC5 protein encoded by Mungbean yellow mosaic India virus is a pathogenicity determinant that suppresses RNA silencing-based antiviral defenses
The AC5 protein encoded by Mungbean yellow mosaic India virus is a pathogenicity determinant that suppresses RNA silencing-based antiviral defenses
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DOI：
10.1111/nph.13473
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发表时间：
2015-10-01
期刊：
影响因子：
9.4
通讯作者：
Zhou, Xueping
中科院分区：
文献类型：
--
作者：
Li, Fangfang;Xu, Xiongbiao;Zhou, Xueping
双生病毒科双生病毒以互补链DNA为模板编码4种蛋白质（AC 1/C1 ~ AC 4/C4）。虽然AC 5/C5编码序列越来越多地注释在数据库中的许多菜豆病毒，这种推定的蛋白质在病毒infection. There的进化关系和功能是模糊的，我们证明了几个重要的功能的AC 5蛋白的二分菜豆病毒，绿豆黄花叶印度病毒（MYMIV）。突变分析和转基因表达表明AC 5在MYMIV感染中起关键作用。将AC 5从马铃薯X病毒（PVX）载体中异位表达，在本氏烟草（Nicotiana benthamiana）中诱导了严重的花叶症状和过敏样反应，并且MYMIV AC 5能有效抑制单链RNA诱导的转录后基因沉默，而对双链RNA没有影响。AC 5还能够通过减少启动子序列的甲基化来逆转绿色荧光蛋白转基因的转录基因沉默，这可能是通过抑制N.我们的研究结果表明，MYMIV AC 5是一个致病性决定因子和一个有效的RNA沉默抑制因子，采用新的机制来抑制抗病毒防御，并表明AC 5功能可能是保守的许多菜豆花叶病毒。
It is generally accepted that begomoviruses in the family Geminiviridae encode four proteins (from AC1/C1 to AC4/C4) using the complementary-sense DNA as template. Although AC5/C5 coding sequences are increasingly annotated in databases for many begomoviruses, the evolutionary relationships and functions of this putative protein in viral infection are obscure.Here, we demonstrate several important functions of the AC5 protein of a bipartite begomovirus, Mungbean yellow mosaic India virus (MYMIV). Mutational analyses and transgenic expression showed that AC5 plays a critical role in MYMIV infection. Ectopic expression of AC5 from a Potato virus X (PVX) vector resulted in severe mosaic symptoms followed by a hypersensitive-like response in Nicotiana benthamiana.Furthermore, MYMIV AC5 effectively suppressed post-transcriptional gene silencing induced by single-stranded but not double-stranded RNA. AC5 was also able to reverse transcriptional gene silencing of a green fluorescent protein transgene by reducing methylation of promoter sequences, probably through repressing expression of a CHH cytosine methyltransferase (DOMAINS REARRANGED METHYLTRANSFERASE2) in N. benthamiana.Our results demonstrate that MYMIV AC5 is a pathogenicity determinant and a potent RNA silencing suppressor that employs novel mechanisms to suppress antiviral defenses, and suggest that the AC5 function may be conserved among many begomoviruses.