Effects of the Crinivirus Coat Protein-Interacting Plant Protein SAHH on Post-Transcriptional RNA Silencing and Its Suppression
Effects of the Crinivirus Coat Protein-Interacting Plant Protein SAHH on Post-Transcriptional RNA Silencing and Its Suppression
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DOI：
10.1094/mpmi-02-13-0037-r
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发表时间：
2013-09-01
影响因子：
3.5
通讯作者：
Moriones, Enrique
中科院分区：
文献类型：
--
作者：
Carmen Canizares, M.;Lozano-Duran, Rosa;Moriones, Enrique
在植物中，转录后基因沉默（PTGS）是双链RNA（dsRNA）诱导的RNA降解的序列特异性机制，双链RNA被加工成小干扰RNA（siRNA）。 siRNA 被甲基化，从而通过 S-腺苷甲硫氨酸依赖性 RNA 甲基转移酶 HEN1 的活性来稳定。 PTGS 通过宿主编码的 RNA 依赖性 RNA 聚合酶 (RDR) 进行扩增，产生 dsRNA，并被加工成二级 siRNA。为了抵消宿主的这种 RNA 沉默介导的反应，植物病毒表达具有沉默抑制活性的蛋白质。在这里，我们报道了crinivirus（长线病毒科，crinivirus属）番茄失绿病毒的外壳蛋白（CP），一种已知的沉默抑制因子，与S-腺苷高半胱氨酸水解酶（SAHH）相互作用，SAHH是维持甲基循环和S-腺苷甲硫氨酸依赖性甲基转移酶活性所必需的植物蛋白。我们的结果表明，通过增加 RDR6 作用产生的二级 siRNA 的积累，SAHH 增强了局部 RNA 沉默。尽管 SAHH 的下调可以防止局部沉默，但它会增强全身沉默的传播。我们的结果还表明，SAHH 在抑制局部 RNA 沉默方面发挥着重要作用，不仅对 crinivirus 番茄褪绿病毒 CP 的抑制，而且对马铃薯病毒 Y 病毒的多功能辅助成分蛋白酶的抑制也很重要。
In plants, post-transcriptional gene silencing (PTGS) is a sequence-specific mechanism of RNA degradation induced by double-stranded RNA (dsRNA), which is processed into small interfering RNAs (siRNAs). siRNAs are methylated and, thereby, stabilized by the activity of the S-adenosylmethionine-dependent RNA methyltransferase HEN1. PTGS is amplified by host-encoded RNA-dependent RNA polymerases (RDR), which generate dsRNA that is processed into secondary siRNAs. To counteract this RNA silencing-mediated response of the host, plant viruses express proteins with silencing suppression activity. Here, we report that the coat protein (CP) of crinivirus (family Closteroviridae, genus Crinivirus) Tomato chlorosis virus, a known suppressor of silencing, interacts with S-adenosylhomocysteine hydrolase (SAHH), a plant protein essential for sustaining the methyl cycle and S-adenosylmethionine-dependent methyltransferase activity. Our results show that, by contributing to an increased accumulation of secondary siRNAs generated by the action of RDR6, SAHH enhances local RNA silencing. Although downregulation of SAHH prevents local silencing, it enhances the spread of systemic silencing. Our results also show that SAHH is important in the suppression of local RNA silencing not only by the crinivirus Tomato chlorosis virus CP but also by the multifunctional helper component-proteinase of the potyvirus Potato virus Y.