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Mõttus J, Maiste S, Eek P, Truve E, Sarmiento C. Mutational analysis of Arabidopsis thaliana ABCE2 identifies important motifs for its RNA silencing suppressor function. PLANT BIOLOGY (STUTTGART, GERMANY) 2021; 23:21-31. [PMID: 33040451 PMCID: PMC7839781 DOI: 10.1111/plb.13193] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 07/29/2020] [Accepted: 09/22/2020] [Indexed: 06/11/2023]
Abstract
ATP-binding cassette sub-family E member 1 (ABCE1) is recognized as a strongly conserved ribosome recycling factor, indispensable for translation in archaea and eukaryotes, however, its role in plants remains largely unidentified. Arabidopsis thaliana encodes two paralogous ABCE proteins (AtABCE1 and AtABCE2), sharing 81% identity. We previously reported that AtABCE2 functions as a suppressor of RNA silencing and that its gene is ubiquitously expressed. Here we describe the structural requirements of AtABCE2 for its suppressor function. Using agroinfiltration assays, we transiently overexpressed mutated versions of AtABCE2 together with GFP, to induce silencing in GFP transgenic Nicotiana benthamiana leaves. The influence of mutations was analysed at both local and systemic levels by in vivo imaging of GFP, Northern blot analysis of GFP siRNAs and observation of plants under UV light. Mutants of AtABCE2 with impaired ATP binding in either active site I or II failed to suppress GFP RNA silencing. Mutations disrupting ATP hydrolysis influenced the suppression of silencing differently at active site I or II. We also found that the N-terminal iron-sulphur cluster domain of AtABCE2 is crucial for its suppressor function. Meaningfully, the observed structural requirements of AtABCE2 for RNA silencing suppression were found to be similar to those of archaeal ABCE1 needed for ribosome recycling. AtABCE2 might therefore suppress RNA silencing via supporting the competing RNA degradation mechanisms associated with ribosome recycling.
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Affiliation(s)
- J. Mõttus
- Department of Chemistry and BiotechnologyTallinn University of TechnologyTallinnEstonia
| | - S. Maiste
- Department of Chemistry and BiotechnologyTallinn University of TechnologyTallinnEstonia
| | - P. Eek
- Department of Chemistry and BiotechnologyTallinn University of TechnologyTallinnEstonia
| | - E. Truve
- Department of Chemistry and BiotechnologyTallinn University of TechnologyTallinnEstonia
| | - C. Sarmiento
- Department of Chemistry and BiotechnologyTallinn University of TechnologyTallinnEstonia
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Peng C, Zhang A, Wang Q, Song Y, Zhang M, Ding X, Li Y, Geng Q, Zhu C. Ultrahigh-activity immune inducer from Endophytic Fungi induces tobacco resistance to virus by SA pathway and RNA silencing. BMC PLANT BIOLOGY 2020; 20:169. [PMID: 32293278 PMCID: PMC7160901 DOI: 10.1186/s12870-020-02386-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Accepted: 04/05/2020] [Indexed: 05/07/2023]
Abstract
BACKGROUND Plant viruses cause severe economic losses in agricultural production. An ultrahigh activity plant immune inducer (i.e., ZhiNengCong, ZNC) was extracted from endophytic fungi, and it could promote plant growth and enhance resistance to bacteria. However, the antiviral function has not been studied. Our study aims to evaluate the antiviral molecular mechanisms of ZNC in tobacco. RESULTS Here, we used Potato X virus (PVX), wild-type tobacco and NahG transgenic tobacco as materials to study the resistance of ZNC to virus. ZNC exhibited a high activity in enhancing resistance to viruses and showed optimal use concentration at 100-150 ng/mL. ZNC also induced reactive oxygen species accumulation, increased salicylic acid (SA) content by upregulating the expression of phenylalanine ammonia lyase (PAL) gene and activated SA signaling pathway. We generated transcriptome profiles from ZNC-treated seedlings using RNA sequencing. The first GO term in biological process was positive regulation of post-transcriptional gene silencing, and the subsequent results showed that ZNC promoted RNA silencing. ZNC-sprayed wild-type leaves showed decreased infection areas, whereas ZNC failed to induce a protective effect against PVX in NahG leaves. CONCLUSION All results indicate that ZNC is an ultrahigh-activity immune inducer, and it could enhance tobacco resistance to PVX at low concentration by positively regulating the RNA silencing via SA pathway. The antiviral mechanism of ZNC was first revealed in this study, and this study provides a new antiviral bioagent.
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Affiliation(s)
- Chune Peng
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong, 271018, P.R. China
| | - Ailing Zhang
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong, 271018, P.R. China
| | - Qingbin Wang
- Shandong Pengbo Biotechnology Co., LTD, Tai'an, Shandong, 271018, P.R. China
- National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources; National Engineering & Technology Research Center for Slow and Controlled Release Fertilizers, College of Resources and Environment, Shandong Agricultural University, Tai'an, Shandong, 271018, P.R. China
| | - Yunzhi Song
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong, 271018, P.R. China
| | - Min Zhang
- National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources; National Engineering & Technology Research Center for Slow and Controlled Release Fertilizers, College of Resources and Environment, Shandong Agricultural University, Tai'an, Shandong, 271018, P.R. China
| | - Xinhua Ding
- State Key Laboratory of Crop Biology, College of Plant Protection, Shandong Agricultural University, Tai'an, Shandong, 271018, P.R. China
| | - Yang Li
- Shandong Pengbo Biotechnology Co., LTD, Tai'an, Shandong, 271018, P.R. China
| | - Quanzheng Geng
- Shandong Pengbo Biotechnology Co., LTD, Tai'an, Shandong, 271018, P.R. China
| | - Changxiang Zhu
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong, 271018, P.R. China.
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Huang X, Yu R, Li W, Geng L, Jing X, Zhu C, Liu H. Identification and characterisation of a glycine-rich RNA-binding protein as an endogenous suppressor of RNA silencing from Nicotiana glutinosa. PLANTA 2019; 249:1811-1822. [PMID: 30840177 DOI: 10.1007/s00425-019-03122-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 02/27/2019] [Indexed: 05/08/2023]
Abstract
MAIN CONCLUSION This study shows that NgRBP suppresses both local and systemic RNA silencing induced by sense- or double-stranded RNA, and the RNA binding activity is essential for its function. To counteract host defence, many plant viruses encode viral suppressors of RNA silencing targeting various stages of RNA silencing. There is increasing evidence that the plants also encode endogenous suppressors of RNA silencing (ESR) to regulate this pathway. In this study, using Agrobacterium infiltration assays, we characterized NgRBP, a glycine-rich RNA-binding protein from Nicotiana glutinosa, as an ESR. Our results indicated that NgRBP suppressed both local and systemic RNA silencing induced by sense- or double-stranded RNA. We also demonstrated that NgRBP could promote Potato Virus X (PVX) infection in N. benthamiana. NgRBP knockdown by virus-induced gene silencing enhanced PVX and Cucumber mosaic virus resistance in N. glutinosa. RNA immunoprecipitation and electrophoretic mobility shift assays showed that NgRBP bound to GFP mRNA, dsRNA rather than siRNA. These findings provide the evidence that NgRBP acts as an ESR and the RNA affinity of NgRBP plays the key role in its ESR activity. NgRBP responds to multiple signals such as ABA, MeJA, SA, and Tobacco mosaic virus infection. Therefore, it could participate in the regulation of gene expression under specific conditions.
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Affiliation(s)
- Xu Huang
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong, China
| | - Ru Yu
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong, China
| | - Wenjing Li
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong, China
| | - Liwei Geng
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong, China
| | - Xiuli Jing
- Institute of Immunology, Taishan Medical University, Tai'an, Shandong, China
| | - Changxiang Zhu
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong, China
| | - Hongmei Liu
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong, China.
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Herpes Simplex Virus 1 Lytic Infection Blocks MicroRNA (miRNA) Biogenesis at the Stage of Nuclear Export of Pre-miRNAs. mBio 2019; 10:mBio.02856-18. [PMID: 30755517 PMCID: PMC6372804 DOI: 10.1128/mbio.02856-18] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Various mechanisms have been identified by which viruses target host small RNA biogenesis pathways to achieve optimal infection outcomes. Herpes simplex virus 1 (HSV-1) is a ubiquitous human pathogen whose successful persistence in the host entails both productive (“lytic”) and latent infection. Although many HSV-1 miRNAs have been discovered and some are thought to help control the lytic/latent switch, little is known about regulation of their biogenesis. By characterizing expression of both pre-miRNAs and mature miRNAs under various conditions, this study revealed striking differences in miRNA biogenesis between lytic and latent infection and uncovered a regulatory mechanism that blocks pre-miRNA nuclear export and is dependent on viral protein ICP27 and viral DNA synthesis. This mechanism represents a new virus-host interaction that could limit the repressive effects of HSV-1 miRNAs hypothesized to promote latency and may shed light on the regulation of miRNA nuclear export, which has been relatively unexplored. Herpes simplex virus 1 (HSV-1) switches between two infection programs, productive (“lytic”) and latent infection. Some HSV-1 microRNAs (miRNAs) have been hypothesized to help control this switch, and yet little is known about regulation of their expression. Using Northern blot analyses, we found that, despite inherent differences in biogenesis efficiency among six HSV-1 miRNAs, all six exhibited high pre-miRNA/miRNA ratios during lytic infection of different cell lines and, when detectable, in acutely infected mouse trigeminal ganglia. In contrast, considerably lower ratios were observed in latently infected ganglia and in cells transduced with lentiviral vectors expressing the miRNAs, suggesting that HSV-1 lytic infection blocks miRNA biogenesis. This phenomenon is not specific to viral miRNAs, as a host miRNA expressed from recombinant HSV-1 also exhibited high pre-miRNA/miRNA ratios late during lytic infection. The levels of most of the mature miRNAs remained stable during infection in the presence of actinomycin D, indicating that the high ratios are due to inefficient pre-miRNA conversion to miRNA. Cellular fractionation experiments showed that late (but not early) during infection, pre-miRNAs were enriched in the nucleus and depleted in the cytoplasm, indicating that nuclear export was blocked. A mutation eliminating ICP27 expression or addition of acyclovir reduced pre-miRNA/miRNA ratios, but mutations drastically reducing Us11 expression did not. Thus, HSV-1 lytic infection inhibits miRNA biogenesis at the step of nuclear export and does so in an ICP27- and viral DNA synthesis-dependent manner. This mechanism may benefit the virus by reducing expression of repressive miRNAs during lytic infection while permitting elevated expression during latency.
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Yu R, Jing X, Li W, Xu J, Xu Y, Geng L, Zhu C, Liu H. Non-structural protein 1 from avian influenza virus H9N2 is an efficient RNA silencing suppressor with characteristics that differ from those of Tomato bushy stunt virus p19. Virus Genes 2018; 54:368-375. [PMID: 29480423 DOI: 10.1007/s11262-018-1544-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 02/19/2018] [Indexed: 10/17/2022]
Abstract
Non-structural protein 1 (NS1) of influenza A virus is a multifunctional dimeric protein that contains a conserved N-terminal RNA binding domain. Studies have shown that NS1 suppresses RNA silencing and the NS1 proteins encoded by different influenza A virus strains exhibit differential RNA silencing suppression activities. In this study, we showed that the NS1 protein from avian influenza virus (AIV) H9N2 suppressed systemic RNA silencing induced by sense RNA or dsRNA. It resulted in more severe Potato virus X symptom, but could not reverse established systemic green fluorescent protein silencing in Nicotiana benthamiana. In addition, its systemic silencing suppression activity was much weaker than that of p19. The local silencing suppression activity of AIV H9N2 NS1 was most powerful at 7 dpi and was even stronger than that of p19. And the inhibition ability to RNA silencing of NS1 is stronger than that of p19 in human cells. Collectively, these results indicate that AIV H9N2 NS1 is an effective RNA silencing suppressor that likely targets downstream step(s) of dsRNA formation at an early stage in RNA silencing. Although NS1 and p19 both bind siRNA, their suppression mechanisms seem to differ because of differences in their suppression activities at various times post-infiltration and because p19 can reverse established systemic RNA silencing, but NS1 cannot.
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Affiliation(s)
- Ru Yu
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, 271018, China
| | - Xiuli Jing
- Institute of Immunology, Taishan Medical University, Tai'an, 271000, China
| | - Wenjing Li
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, 271018, China
| | - Jie Xu
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, 271018, China
| | - Yang Xu
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, 271018, China
| | - Liwei Geng
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, 271018, China
| | - Changxiang Zhu
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, 271018, China
| | - Hongmei Liu
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, 271018, China.
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Jia G, Li W, Fan M, Yu R, Xu Y, Geng L, Zhang J, Zhu C, Liu H. Pentapeptide-insertion scanning mutational analysis of turkey herpesvirus HVT063 reveals residues important for its RNA silencing suppression activity. Arch Virol 2018; 163:167-174. [PMID: 29052787 DOI: 10.1007/s00705-017-3595-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2017] [Accepted: 09/26/2017] [Indexed: 11/30/2022]
Abstract
HVT063, an RNA-binding protein encoded by turkey herpesvirus, has been shown previously to suppress RNA silencing. Here, a scanning library produced by pentapeptide-insertion scanning mutagenesis was used to identify key residues associated with its RNA silencing suppressor (RSS) activity. Forty-two in-frame insertion mutants of HVT063 protein were evaluated for their RSS activity using the dual-luciferase transient expressing assay system. Sixteen mutations resulted in a loss of RSS activity, 20 mutations resulted in decreased RSS activity, and six mutations exhibited high RSS activity similar to wild-type HVT063. Based on a three-dimensional structure prediction, most of the loss-of-function mutations were located around a predominantly α-helical region at the C-terminal end of HVT063. In particular, a conserved domain in this region, named herpes_UL69, showed low tolerance for five-amino-acid insertions. Combined with the results of our previous studies, basic amino acids could play a key role in RSS activity. These results also demonstrate that pentapeptide-insertion scanning mutagenesis combined with dual-luciferase assays is an effective method to functionally characterize RSSs.
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Affiliation(s)
- Gang Jia
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, 271018, Shandong, China
| | - Wenjing Li
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, 271018, Shandong, China
| | - Meina Fan
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, 271018, Shandong, China
| | - Ru Yu
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, 271018, Shandong, China
| | - Yang Xu
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, 271018, Shandong, China
| | - Liwei Geng
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, 271018, Shandong, China
| | - Jiedao Zhang
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, 271018, Shandong, China
| | - Changxiang Zhu
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, 271018, Shandong, China
| | - Hongmei Liu
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, 271018, Shandong, China.
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Morozov SY, Lazareva EA, Solovyev AG. RNA helicase domains of viral origin in proteins of insect retrotransposons: possible source for evolutionary advantages. PeerJ 2017; 5:e3673. [PMID: 28828268 PMCID: PMC5563155 DOI: 10.7717/peerj.3673] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 07/21/2017] [Indexed: 12/15/2022] Open
Abstract
Recently, a novel phenomenon of horizontal gene transfer of helicase-encoding sequence from positive-stranded RNA viruses to LINE transposons in insect genomes was described. TRAS family transposons encoding an ORF2 protein, which comprised all typical functional domains and an additional helicase domain, were found to be preserved in many families during the evolution of the order Lepidoptera. In the present paper, in species of orders Hemiptera and Orthoptera, we found helicase domain-encoding sequences integrated into ORF1 of retrotransposons of the Jockey family. RNA helicases encoded by transposons of TRAS and Jockey families represented separate brunches in a phylogenetic tree of helicase domains and thus could be considered as independently originated in the evolution of insect transposons. Transcriptome database analyses revealed that both TRAS and Jockey transposons encoding the helicase domain represented transcribed genome sequences. Moreover, the transposon-encoded helicases were found to contain the full set of conserved motifs essential for their enzymatic activities. Taking into account the previously reported ability of RNA helicase encoded by TRAS ORF2 to suppress post-transcriptional RNA silencing, we propose possible scenarios of evolutionary fixation of actively expressed functional helicases of viral origin in insect retrotransposons as genetic elements advantageous for both transposons and their insect hosts.
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Affiliation(s)
- Sergey Y Morozov
- Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, Russia
| | - Ekaterina A Lazareva
- Department of Virology, Biological Faculty, Moscow State University, Moscow, Russia
| | - Andrey G Solovyev
- Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, Russia.,Institute of Molecular Medicine, Sechenov First Moscow State Medical University, Moscow, Russia
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Ma L, Huang X, Yu R, Jing XL, Xu J, Wu CA, Zhu CX, Liu HM. Elevated Ambient Temperature Differentially Affects Virus Resistance in Two Tobacco Species. PHYTOPATHOLOGY 2016; 106:94-100. [PMID: 26474332 DOI: 10.1094/phyto-11-14-0300-r] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Antiviral defense of plants is usually enhanced by an elevated temperature under natural conditions. In order to better understand this phenomenon, we carried out temperature shift experiments with Nicotiana glutinosa plants that were infected with Potato virus X (PVX) or the necrotic strain of Potato virus Y (PVY(N)). The virus titer of the plants was found to be much lower when they were maintained at 30°C compared with 22°C, particularly in the upper leaves. PVX resistance at 30°C persisted for a short period even when temperature was shifted back to 22°C. In contrast, N. benthamiana lost the virus resistance immediately after the temperature dropped to 22°C. Expression analysis of two RNA-dependent RNA polymerases in N. glutinosa (NgRDR) showed that a 12-day treatment at 30°C increased the expression of NgRDR1, while NgRDR6 was not affected. In addition, the NgRDR6 mRNA level correlated with the PVX titer but was unaffected by PVY(N) infection. These observations indicate that PVX and PVY(N), although they are both RNA viruses, might trigger different defense responses at elevated temperatures. Our study provides valuable data for a better understanding of the temperature-regulated host virus interaction.
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Affiliation(s)
- L Ma
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong, China
| | - X Huang
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong, China
| | - R Yu
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong, China
| | - X L Jing
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong, China
| | - J Xu
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong, China
| | - C A Wu
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong, China
| | - C X Zhu
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong, China
| | - H M Liu
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong, China
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Lazareva E, Lezzhov A, Vassetzky N, Solovyev A, Morozov S. Acquisition of Full-Length Viral Helicase Domains by Insect Retrotransposon-Encoded Polypeptides. Front Microbiol 2015; 6:1447. [PMID: 26733982 PMCID: PMC4686597 DOI: 10.3389/fmicb.2015.01447] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 12/04/2015] [Indexed: 12/18/2022] Open
Abstract
Recent metagenomic studies in insects identified many sequences unexpectedly closely related to plant virus genes. Here we describe a new example of this kind, insect R1 LINEs with an additional C-terminal domain in their open reading frame 2. This domain is similar to NTPase/helicase (SF1H) domains, which are found in replicative proteins encoded by plant viruses of the genus Tobamovirus. We hypothesize that the SF1H domain could be acquired by LINEs, directly or indirectly, upon insect feeding on virus-infected plants. Possible functions of this domain in LINE transposition and involvement in LINEs counteraction the silencing-based cell defense against retrotransposons are discussed.
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Affiliation(s)
- Ekaterina Lazareva
- Department of Virology, Faculty of Biology, Lomonosov Moscow State University Moscow, Russia
| | - Alexander Lezzhov
- Department of Virology, Faculty of Biology, Lomonosov Moscow State University Moscow, Russia
| | - Nikita Vassetzky
- Laboratory of Eukaryotic Genome Evolution, Engelhardt Institute of Molecular Biology, Russian Academy of Sciences Moscow, Russia
| | - Andrey Solovyev
- Genetic Engineering of Plant Viruses, A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University Moscow, Russia
| | - Sergey Morozov
- Department of Virology, Faculty of Biology, Lomonosov Moscow State UniversityMoscow, Russia; Genetic Engineering of Plant Viruses, A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State UniversityMoscow, Russia
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10
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Jing X, Xu J, Fan M, Ma L, Huang X, Wang X, Sun S, Zhu C, Liu H. Mutation analysis of the RNA silencing suppressor NS1 encoded by avian influenza virus H9N2. J Gen Virol 2015; 96:1613-8. [PMID: 25701825 DOI: 10.1099/vir.0.000095] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Non-structural protein 1 (NS1) binds small interfering RNA and suppresses RNA silencing in plants, but the underlying mechanism of this suppression is not well understood. Therefore, here we characterized NS1 encoded by the avian influenza virus H9N2. The NS1 protein was able to suppress RNA silencing induced by either sense RNA or double-stranded RNA (dsRNA). Using deletion and point mutants, we discovered that the first 70 residues of NS1 could suppress RNA silencing triggered by sense transgene, but this sequence was not sufficient to block dsRNA-induced silencing. Any mutations of two arginine residues (35R and 46R) of NS1, which contribute to its homodimeric structure, caused the loss of its silencing suppression activity. These results indicate that the region after residue 70 of NS1 is essential for the repression activity on dsRNA-induced RNA silencing, and that the dimeric structure of NS1 plays a critical role in its RNA silencing suppression function.
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Affiliation(s)
- Xiuli Jing
- 1State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong, PR China 2Institute of Immunology, Taishan Medical University, Tai'an, Shandong, PR China
| | - Jie Xu
- 1State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong, PR China
| | - Meina Fan
- 1State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong, PR China
| | - Lin Ma
- 1State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong, PR China
| | - Xu Huang
- 1State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong, PR China
| | - Xiaoyun Wang
- 1State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong, PR China
| | - Shuhong Sun
- 3College of Animal Science and Veterinary Medicine, Shandong Agricultural University, Tai'an, Shandong, PR China
| | - Changxiang Zhu
- 1State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong, PR China
| | - Hongmei Liu
- 1State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong, PR China
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Lu Y, Peng JJ, Yu ZB, Du JJ, Xu JN, Wang XY. Thylakoid membrane oxidoreductase LTO1/AtVKOR is involved in ABA-mediated response to osmotic stress in Arabidopsis. PHYSIOLOGIA PLANTARUM 2015; 154:28-38. [PMID: 25171375 DOI: 10.1111/ppl.12268] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2014] [Revised: 07/04/2014] [Accepted: 07/13/2014] [Indexed: 06/03/2023]
Abstract
Arabidopsis lumen thiol oxidoreductase 1 (LTO1) - the At4g35760 gene product - was previously found to be related to reactive oxygen species (ROS) accumulation. Here, we show that ROS accumulated in a mutant Arabidopsis line (lto1-2, mutant of LTO1/AtVKOR) under osmotic stress at a higher level than that observed in wild-type and transgenic complemented plants of the lto1-2 mutant (lto1-2C, transgenic complemented plants of lto1-2). Because ROS accumulation in osmotic stress is triggered by abscisic acid (ABA), an ABA-responsive gene, Annexin 1 (AnnAt1), was selected to study the response. Osmotic stress or exogenous ABA can significantly upregulate the transcription of AnnAt1 in wild-type and lto1-2C plants. Only a slight change in the transcriptional abundance of AnnAt1 was observed under osmotic stress in the lto1-2 mutant, but exogenous ABA application could increase the expression of AnnAt1, which suggested that exogenous ABA had a partial complementation role. Because the transcription of AnnAt1 is regulated by ABRE (ABA-responsive elements) binding proteins (AREBs)/ABRE binding factors (ABFs), the expression of AREBs/ABFs was also analyzed. The transcription of AREBs/ABFs in the lto1-2 mutant was not induced by osmotic stress but was significantly upregulated by exogenous ABA, which significantly differs from the wild-type and lto1-2C plant responses. Similarly, the expression of another ABA-responsive gene, RD29B (responsive to desiccation stress gene 29B), in the lto1-2 mutant was also upregulated by exogenous ABA. The partial complementation of mutants by ABA indicated that the ABA signal transduction pathway was not significantly affected in the lto1-2 mutant. Taken together, these results suggest that LTO1 is involved in ABA-mediated response to osmotic stress, possibly by affecting the biosynthesis of endogenous ABA.
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Affiliation(s)
- Ying Lu
- College of Life Science, Shandong Agricultural University, Taian, 271018, China
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12
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Cañizares MC, Lozano-Durán R, Canto T, Bejarano ER, Bisaro DM, Navas-Castillo J, Moriones E. Effects of the crinivirus coat protein-interacting plant protein SAHH on post-transcriptional RNA silencing and its suppression. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2013; 26:1004-15. [PMID: 23697374 DOI: 10.1094/mpmi-02-13-0037-r] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
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.
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Affiliation(s)
- M Carmen Cañizares
- Instituto de Hortofruticultura Subtropical y Mediterránea La Mayora, Universidad de Málaga-Consejo Superior de Investigaciones Científicas IHSM-UMA-CSIC, Estación Experimental La Mayora, Málaga, Spain
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13
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Lu Y, Wang HR, Li H, Cui HR, Feng YG, Wang XY. A chloroplast membrane protein LTO1/AtVKOR involving in redox regulation and ROS homeostasis. PLANT CELL REPORTS 2013; 32:1427-40. [PMID: 23689258 DOI: 10.1007/s00299-013-1455-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Revised: 04/20/2013] [Accepted: 04/29/2013] [Indexed: 05/08/2023]
Abstract
The role of LTO1/ At VKOR-DsbA in ROS homeostasis and in redox regulation of cysteine-containing proteins in chloroplast was studied in lto1 - 2 mutant, and a potential target of LTO1 was captured. A chloroplast membrane protein LTO1/AtVKOR-DsbA encoded by the gene At4g35760 was recently found to be an oxidoreductase and involved in assembly of PSII. Here, the growth of a mutant lto1-2 line of Arabidopsis was found to be severely stunted and transgenic complementation ultimately demonstrated the phenotype changes were due to this gene. A proteomic experiment identified 23 proteins presenting a differential abundance in lto1-2 compared with wild-type plants, including components in PSII and proteins scavenging active oxygen. Three scavengers of active oxygen, L-ascorbate peroxidase 1, peroxisomal catalase 2, dehydroascorbate reductase 1, are reduced in lto1-2 plants, corresponding to high levels of accumulation of reactive oxygen species (ROS). The photosynthetic activities of PSII and the quantity of core protein D1 decreased significantly in lto1-2. Further investigation showed the synthesis of D1 was not affected in mutants both at transcription and translation levels. The soluble DsbA-like domain of LTO1 was found to have reduction, oxidation and isomerization activities, and could promote the formation of disulfide bonds in a lumenal protein, FKBP13. A potential target of LTO1 was captured which was involving in chlorophyll degradation and photooxidative stress response. Experimental results imply that LTO1 plays important roles in redox regulation, ROS homeostasis and maintenance of PSII.
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Affiliation(s)
- Ying Lu
- College of Life Science, Shandong Agricultural University, Taian 271018, Shandong, People's Republic of China
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14
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Valli A, Busnadiego I, Maliogka V, Ferrero D, Castón JR, Rodríguez JF, García JA. The VP3 factor from viruses of Birnaviridae family suppresses RNA silencing by binding both long and small RNA duplexes. PLoS One 2012; 7:e45957. [PMID: 23049903 PMCID: PMC3458112 DOI: 10.1371/journal.pone.0045957] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2012] [Accepted: 08/23/2012] [Indexed: 12/23/2022] Open
Abstract
RNA silencing is directly involved in antiviral defense in a wide variety of eukaryotic organisms, including plants, fungi, invertebrates, and presumably vertebrate animals. The study of RNA silencing-mediated antiviral defences in vertebrates is hampered by the overlap with other antiviral mechanisms; thus, heterologous systems are often used to study the interplay between RNA silencing and vertebrate-infecting viruses. In this report we show that the VP3 protein of the avian birnavirus Infectious bursal disease virus (IBDV) displays, in addition to its capacity to bind long double-stranded RNA, the ability to interact with double-stranded small RNA molecules. We also demonstrate that IBDV VP3 prevents the silencing mediated degradation of a reporter mRNA, and that this silencing suppression activity depends on its RNA binding ability. Furthermore, we find that the anti-silencing activity of IBDV VP3 is shared with the homologous proteins expressed by both insect- and fish-infecting birnaviruses. Finally, we show that IBDV VP3 can functionally replace the well-characterized HCPro silencing suppressor of Plum pox virus, a potyvirus that is unable to infect plants in the absence of an active silencing suppressor. Altogether, our results support the idea that VP3 protects the viral genome from host sentinels, including those of the RNA silencing machinery.
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Affiliation(s)
- Adrian Valli
- Centro Nacional de Biotecnología-CSIC, Madrid, Spain
| | | | | | - Diego Ferrero
- Centro Nacional de Biotecnología-CSIC, Madrid, Spain
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15
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Morozov SY, Solovyev AG. Did silencing suppression counter-defensive strategy contribute to origin and evolution of the triple gene block coding for plant virus movement proteins? FRONTIERS IN PLANT SCIENCE 2012; 3:136. [PMID: 22783263 PMCID: PMC3390553 DOI: 10.3389/fpls.2012.00136] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Accepted: 06/05/2012] [Indexed: 05/25/2023]
Affiliation(s)
- Sergey Y. Morozov
- Belozersky Institute of Physico-Chemical Biology, Moscow State UniversityMoscow, Russia
| | - Andrey G. Solovyev
- Belozersky Institute of Physico-Chemical Biology, Moscow State UniversityMoscow, Russia
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