Suppression of RNAi by dsRNA-degrading RNaseIII enzymes of viruses in animals and plants.
Suppression of RNAi by dsRNA-degrading RNaseIII enzymes of viruses in animals and plants.
复制标题
DOI：
10.1371/journal.ppat.1004711
复制
发表时间：
2015-03
期刊：
影响因子：
6.7
通讯作者：
Valkonen JP
中科院分区：
文献类型：
--
作者：
Weinheimer I;Jiu Y;Rajamäki ML;Matilainen O;Kallijärvi J;Cuellar WJ;Lu R;Saarma M;Holmberg CI;Jäntti J;Valkonen JP
某些感染植物、昆虫、鱼类或变温动物的RNA和DNA病毒编码1类RNaseIII核糖核酸内切酶样蛋白。报道了侵染鱼类的石鲷虹膜病毒和侵染植物的甘薯绿僵病毒（SPCSV）的RNaseIII的dsrna特异性核糖核酸内酶活性。SPCSV和Heliothis virescens ascovirus感染昆虫的RNaseIII抑制宿主抗病毒RNA干扰（RNAi）途径已被证实。病毒rnaseii在不同王国的非宿主生物中对RNAi的抑制尚不清楚。我们在非宿主植物Nicotiana benthamiana和线虫Caenorhabditis elegans中表达了棘鱼虹膜病毒的RNaseIII基因PPR3，发现它可以切割双链小干扰RNA （ds-siRNA）分子，这些分子在宿主RNA干扰（RNAi）途径中起关键作用，从而抑制非宿主组织中的RNAi。在benthamiana中，PPR3增强了烟草摇铃病毒RNA1复制子的积累，缺乏16K RNAi抑制子。此外，PPR3抑制单链RNA （ssRNA）介导的RNAi，并在秀丽隐杆线虫中恢复缺乏B2 RNAi抑制因子的禽舍病毒RNA1复制子的复制。催化受损的突变体PPR3-Ala削弱了RNAi的抑制作用。然而，SPCSV产生的RNaseIII （CSR3）在植物中切割- sirna并对抗抗病毒RNAi，却未能抑制秀丽隐杆线虫中ssrna介导的RNAi。在benthamiana叶片中，PPR3抑制了ssRNA和dsRNA诱导的RNAi，逆转了沉默；然而，CSR3仅抑制由ssRNA诱导的RNAi，不能逆转沉默。在黑腹果蝇中，PPR3和CSR3均未抑制反义介导的RNAi。这些结果表明，RNA和DNA病毒的RNaseIII酶抑制RNAi，这需要RNaseIII的催化活性。与其他病毒沉默抑制蛋白相比，RNaseIII酶在不相关的RNA和DNA病毒中是同源的，可以通过基因建模和蛋白质结构预测程序在病毒基因组中检测到。RNA干扰（RNAi）是一种由双链RNA （dsRNA）激活的细胞机制。细胞dsRNA特异性RNaseIII酶（Dicer）识别dsRNA并将其加工成21-25个核苷酸（nt）的双链小干扰rna （ds- sirna）。sirna引导RNAi降解与触发器同源的单链RNA。RNAi调控基因表达，控制转座子，是一种重要的抗病毒防御机制。因此，病毒会编码专门对抗RNAi的蛋白质。本研究比较了鱼类DNA病毒（PPIV）和植物RNA病毒（SPCSV）的RNaseIII酶在非宿主生物中对RNAi的抑制作用。鱼虹膜病毒RNaseIII抑制植物和线虫中的RNAi。它还可以增强植物中RNAi抑制缺陷病毒的积累，抑制抗病毒RNAi，并可以挽救线虫中不相关的RNAi抑制缺陷病毒的增殖。相比之下，植物病毒RNaseIII只能在植物中抑制RNAi。我们的研究结果强调了活性病毒RNaseIII酶抑制RNAi。它们抑制RNAi的活性似乎在不相关的生物体中有所不同。了解这种抑制RNAi的新机制可以为控制含有rnaseiii的病毒在动植物生产中引起的疾病和经济损失提供方法。
Certain RNA and DNA viruses that infect plants, insects, fish or poikilothermic animals encode Class 1 RNaseIII endoribonuclease-like proteins. dsRNA-specific endoribonuclease activity of the RNaseIII of rock bream iridovirus infecting fish and Sweet potato chlorotic stunt crinivirus (SPCSV) infecting plants has been shown. Suppression of the host antiviral RNA interference (RNAi) pathway has been documented with the RNaseIII of SPCSV and Heliothis virescens ascovirus infecting insects. Suppression of RNAi by the viral RNaseIIIs in non-host organisms of different kingdoms is not known. Here we expressed PPR3, the RNaseIII of Pike-perch iridovirus, in the non-hosts Nicotiana benthamiana (plant) and Caenorhabditis elegans (nematode) and found that it cleaves double-stranded small interfering RNA (ds-siRNA) molecules that are pivotal in the host RNA interference (RNAi) pathway and thereby suppresses RNAi in non-host tissues. In N. benthamiana, PPR3 enhanced accumulation of Tobacco rattle tobravirus RNA1 replicon lacking the 16K RNAi suppressor. Furthermore, PPR3 suppressed single-stranded RNA (ssRNA)—mediated RNAi and rescued replication of Flock House virus RNA1 replicon lacking the B2 RNAi suppressor in C. elegans. Suppression of RNAi was debilitated with the catalytically compromised mutant PPR3-Ala. However, the RNaseIII (CSR3) produced by SPCSV, which cleaves ds-siRNA and counteracts antiviral RNAi in plants, failed to suppress ssRNA-mediated RNAi in C. elegans. In leaves of N. benthamiana, PPR3 suppressed RNAi induced by ssRNA and dsRNA and reversed silencing; CSR3, however, suppressed only RNAi induced by ssRNA and was unable to reverse silencing. Neither PPR3 nor CSR3 suppressed antisense-mediated RNAi in Drosophila melanogaster. These results show that the RNaseIII enzymes of RNA and DNA viruses suppress RNAi, which requires catalytic activities of RNaseIII. In contrast to other viral silencing suppression proteins, the RNaseIII enzymes are homologous in unrelated RNA and DNA viruses and can be detected in viral genomes using gene modeling and protein structure prediction programs. RNA interference (RNAi) is a cellular mechanism activated by double-stranded RNA (dsRNA). Cellular dsRNA-specific RNaseIII enzymes (Dicer) recognize dsRNA and process it into double-stranded small interfering RNAs (ds-siRNAs) of 21–25 nucleotides (nt). siRNAs guide RNAi to degrade also single-stranded RNA homologous to the trigger. RNAi regulates gene expression, controls transposons, and represents an important antiviral defense mechanism. Therefore, viruses encode proteins dedicated to countering RNAi. In this study, the RNaseIII enzymes of a fish DNA virus (PPIV) and a plant RNA virus (SPCSV) were compared for suppression of RNAi in non-host organisms. The fish iridovirus RNaseIII suppressed RNAi in a plant and a nematode. It also enhanced accumulation of an RNAi suppressor deficient virus in plants, and suppressed antiviral RNAi and could rescue multiplication of an unrelated, RNAi suppressor-defective virus in nematodes. In contrast, the plant virus RNaseIII could suppress RNAi only in plants. Our results underscore that the active viral RNaseIII enzymes suppress RNAi. Their activity in suppression of RNAi seems to differ for the spectrum of unrelated organisms. Understanding of this novel mechanism of RNAi suppression may inform means of controlling the diseases and economic losses which the RNaseIII-containing viruses cause in animal and plant production.
登录
查看更多内容
影响因子：
5.4
作者：
Guo, Xunyang;Lu, Rui
通讯作者：
Lu, Rui
影响因子：
5.4
作者：
Hussain, Mazhar;Abraham, Alexander M.;Asgari, Sassan
通讯作者：
Asgari, Sassan
影响因子：
5.4
作者：
Guo, Xunyang;Li, Wan-Xiang;Lu, Rui
通讯作者：
Lu, Rui
影响因子：
3.7
作者：
Berry B;Deddouche S;Kirschner D;Imler JL;Antoniewski C
通讯作者：
Antoniewski C
影响因子：
64.8
作者：
Cogoni, C;Macino, G
通讯作者：
Macino, G