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Gapińska M, Zajko W, Skowronek K, Figiel M, Krawczyk P, Egorov A, Dziembowski A, Johansson MO, Nowotny M. Structure-functional characterization of Lactococcus AbiA phage defense system. Nucleic Acids Res 2024; 52:4723-4738. [PMID: 38587192 PMCID: PMC11077055 DOI: 10.1093/nar/gkae230] [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: 05/28/2023] [Revised: 02/01/2024] [Accepted: 03/20/2024] [Indexed: 04/09/2024] Open
Abstract
Bacterial reverse transcriptases (RTs) are a large and diverse enzyme family. AbiA, AbiK and Abi-P2 are abortive infection system (Abi) RTs that mediate defense against bacteriophages. What sets Abi RTs apart from other RT enzymes is their ability to synthesize long DNA products of random sequences in a template- and primer-independent manner. Structures of AbiK and Abi-P2 representatives have recently been determined, but there are no structural data available for AbiA. Here, we report the crystal structure of Lactococcus AbiA polymerase in complex with a single-stranded polymerization product. AbiA comprises three domains: an RT-like domain, a helical domain that is typical for Abi polymerases, and a higher eukaryotes and prokaryotes nucleotide-binding (HEPN) domain that is common for many antiviral proteins. AbiA forms a dimer that distinguishes it from AbiK and Abi-P2, which form trimers/hexamers. We show the DNA polymerase activity of AbiA in an in vitro assay and demonstrate that it requires the presence of the HEPN domain which is enzymatically inactive. We validate our biochemical and structural results in vivo through bacteriophage infection assays. Finally, our in vivo results suggest that AbiA-mediated phage defense may not rely on AbiA-mediated cell death.
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Affiliation(s)
- Marta Gapińska
- Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Weronika Zajko
- Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Krzysztof Skowronek
- Biophysics Core Facility, International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Małgorzata Figiel
- Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Paweł S Krawczyk
- Laboratory of RNA Biology, International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Artyom A Egorov
- Department of Experimental Medical Science, Lund University, 221 00 Lund, Sweden
| | - Andrzej Dziembowski
- Laboratory of RNA Biology, International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Marcus J O Johansson
- Department of Experimental Medical Science, Lund University, 221 00 Lund, Sweden
| | - Marcin Nowotny
- Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, Warsaw, Poland
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2
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Lukhovitskaya N, Brown K, Hua L, Pate AE, Carr JP, Firth AE. A novel ilarvirus protein CP-RT is expressed via stop codon readthrough and suppresses RDR6-dependent RNA silencing. PLoS Pathog 2024; 20:e1012034. [PMID: 38814986 PMCID: PMC11166343 DOI: 10.1371/journal.ppat.1012034] [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: 02/09/2024] [Revised: 06/11/2024] [Accepted: 05/03/2024] [Indexed: 06/01/2024] Open
Abstract
Ilarviruses are a relatively understudied but important group of plant RNA viruses that includes a number of crop pathogens. Their genomes comprise three RNA segments encoding two replicase subunits, movement protein, coat protein (CP), and (in some ilarvirus subgroups) a protein that suppresses RNA silencing. Here we report that, in many ilarviruses, RNA3 encodes an additional protein (termed CP-RT) as a result of ribosomal readthrough of the CP stop codon into a short downstream readthrough (RT) ORF. Using asparagus virus 2 as a model, we find that CP-RT is expressed in planta where it functions as a weak suppressor of RNA silencing. CP-RT expression is essential for persistent systemic infection in leaves and shoot apical meristem. CP-RT function is dependent on a putative zinc-finger motif within RT. Replacing the asparagus virus 2 RT with the RT of an ilarvirus from a different subgroup restored the ability to establish persistent infection. These findings open up a new avenue for research on ilarvirus silencing suppression, persistent meristem invasion and vertical transmission.
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Affiliation(s)
- Nina Lukhovitskaya
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Katherine Brown
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Lei Hua
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
| | - Adrienne E. Pate
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
| | - John P. Carr
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
| | - Andrew E. Firth
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
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3
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Wang J, Hsu Y, Lee Y, Lin N. Importin α2 participates in RNA interference against bamboo mosaic virus accumulation in Nicotiana benthamiana via NbAGO10a-mediated small RNA clearance. MOLECULAR PLANT PATHOLOGY 2024; 25:e13422. [PMID: 38279848 PMCID: PMC10799208 DOI: 10.1111/mpp.13422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 12/20/2023] [Accepted: 12/21/2023] [Indexed: 01/29/2024]
Abstract
Karyopherins, the nucleocytoplasmic transporters, participate in multiple RNA silencing stages by transporting associated proteins into the nucleus. Importin α is a member of karyopherins and has been reported to facilitate virus infection via nuclear import of viral proteins. Unlike other RNA viruses, silencing of importin α2 (α2i) by virus-induced gene silencing (VIGS) boosted the titre of bamboo mosaic virus (BaMV) in protoplasts, and inoculated and systemic leaves of Nicotiana benthamiana. The enhanced BaMV accumulation in importin α2i plants was linked to reduced levels of RDR6-dependent secondary virus-derived small-interfering RNAs (vsiRNAs). Small RNA-seq revealed importin α2 silencing did not affect the abundance of siRNAs derived from host mRNAs but significantly reduced the 21 and 22 nucleotide vsiRNAs in BaMV-infected plants. Deletion of BaMV TGBp1, an RNA silencing suppressor, compromised importin α2i-mediated BaMV enhancement. Moreover, silencing of importin α2 upregulated NbAGO10a, a proviral protein recruited by TGBp1 for BaMV vsiRNAs clearance, but hindered the nuclear import of NbAGO10a. Taken together, these results indicate that importin α2 acts as a negative regulator of BaMV invasion by controlling the expression and nucleocytoplasmic shuttling of NbAGO10a, which removes vsiRNAs via the TGBp1-NbAGO10a-SDN1 pathway. Our findings reveal the hidden antiviral mechanism of importin α2 in countering BaMV infection in N. benthamiana.
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Affiliation(s)
- Jiun‐Da Wang
- Institute of Plant and Microbial BiologyAcademia SinicaTaipeiTaiwan
| | - Yau‐Heiu Hsu
- Graduate Institute of BiotechnologyNational Chung Hsing UniversityTaichungTaiwan
| | - Yun‐Shien Lee
- Department of BiotechnologyMing Chuan UniversityTaipeiTaiwan
| | - Na‐Sheng Lin
- Institute of Plant and Microbial BiologyAcademia SinicaTaipeiTaiwan
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4
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Martin GT, Solares E, Guadardo-Mendez J, Muyle A, Bousios A, Gaut BS. miRNA-like secondary structures in maize ( Zea mays) genes and transposable elements correlate with small RNAs, methylation, and expression. Genome Res 2023; 33:1932-1946. [PMID: 37918960 PMCID: PMC10760457 DOI: 10.1101/gr.277459.122] [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: 11/07/2022] [Accepted: 10/16/2023] [Indexed: 11/04/2023]
Abstract
RNA molecules carry information in their primary sequence and also their secondary structure. Secondary structure can confer important functional information, but it is also a signal for an RNAi-like host epigenetic response mediated by small RNAs (smRNAs). In this study, we used two bioinformatic methods to predict local secondary structures across features of the maize genome, focusing on small regions that had similar folding properties to pre-miRNA loci. We found miRNA-like secondary structures to be common in genes and most, but not all, superfamilies of RNA and DNA transposable elements (TEs). The miRNA-like regions map to a higher diversity of smRNAs than regions without miRNA-like structure, explaining up to 27% of variation in smRNA mapping for some TE superfamilies. This mapping bias is more pronounced among putatively autonomous TEs relative to nonautonomous TEs. Genome-wide, miRNA-like regions are also associated with elevated methylation levels, particularly in the CHH context. Among genes, those with miRNA-like secondary structure are 1.5-fold more highly expressed, on average, than other genes. However, these genes are also more variably expressed across the 26 nested association mapping founder lines, and this variability positively correlates with the number of mapping smRNAs. We conclude that local miRNA-like structures are a nearly ubiquitous feature of expressed regions of the maize genome, that they correlate with higher smRNA mapping and methylation, and that they may represent a trade-off between functional requirements and the potentially negative consequences of smRNA production.
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Affiliation(s)
- Galen T Martin
- Department of Ecology and Evolutionary Biology, University of California, Irvine, California 92617, USA
| | - Edwin Solares
- Department of Ecology and Evolutionary Biology, University of California, Irvine, California 92617, USA
- Department of Ecology and Evolutionary Biology, University of California, Davis, California 95616, USA
| | - Jeanelle Guadardo-Mendez
- Department of Ecology and Evolutionary Biology, University of California, Irvine, California 92617, USA
| | - Aline Muyle
- Department of Ecology and Evolutionary Biology, University of California, Irvine, California 92617, USA
- CEFE, University of Montpellier, CNRS, EPHE, IRD, 34090 Montpellier, France
| | - Alexandros Bousios
- School of Life Sciences, University of Sussex, Brighton BN1 9QG, United Kingdom
| | - Brandon S Gaut
- Department of Ecology and Evolutionary Biology, University of California, Irvine, California 92617, USA;
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5
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Incarbone M, Bradamante G, Pruckner F, Wegscheider T, Rozhon W, Nguyen V, Gutzat R, Mérai Z, Lendl T, MacFarlane S, Nodine M, Scheid OM. Salicylic acid and RNA interference mediate antiviral immunity of plant stem cells. Proc Natl Acad Sci U S A 2023; 120:e2302069120. [PMID: 37824524 PMCID: PMC10589665 DOI: 10.1073/pnas.2302069120] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 08/30/2023] [Indexed: 10/14/2023] Open
Abstract
Stem cells are essential for the development and organ regeneration of multicellular organisms, so their infection by pathogenic viruses must be prevented. Accordingly, mammalian stem cells are highly resistant to viral infection due to dedicated antiviral pathways including RNA interference (RNAi). In plants, a small group of stem cells harbored within the shoot apical meristem generate all postembryonic above-ground tissues, including the germline cells. Many viruses do not proliferate in these cells, yet the molecular bases of this exclusion remain only partially understood. Here, we show that a plant-encoded RNA-dependent RNA polymerase, after activation by the plant hormone salicylic acid, amplifies antiviral RNAi in infected tissues. This provides stem cells with RNA-based virus sequence information, which prevents virus proliferation. Furthermore, we find RNAi to be necessary for stem cell exclusion of several unrelated RNA viruses, despite their ability to efficiently suppress RNAi in the rest of the plant. This work elucidates a molecular pathway of great biological and economic relevance and lays the foundations for our future understanding of the unique systems underlying stem cell immunity.
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Affiliation(s)
- Marco Incarbone
- Gregor Mendel Institute of Molecular Plant Biology, Austrian Academy of Sciences, Vienna BioCenter, Vienna1030, Austria
- Max Planck Institute of Molecular Plant Physiology, Potsdam Science Park, Potsdam14476, Germany
| | - Gabriele Bradamante
- Gregor Mendel Institute of Molecular Plant Biology, Austrian Academy of Sciences, Vienna BioCenter, Vienna1030, Austria
| | - Florian Pruckner
- Gregor Mendel Institute of Molecular Plant Biology, Austrian Academy of Sciences, Vienna BioCenter, Vienna1030, Austria
| | - Tobias Wegscheider
- Gregor Mendel Institute of Molecular Plant Biology, Austrian Academy of Sciences, Vienna BioCenter, Vienna1030, Austria
| | - Wilfried Rozhon
- Department of Agriculture, Ecotrophology, and Landscape Development, Anhalt University of Applied Sciences, Bernburg06406, Germany
| | - Vu Nguyen
- Gregor Mendel Institute of Molecular Plant Biology, Austrian Academy of Sciences, Vienna BioCenter, Vienna1030, Austria
| | - Ruben Gutzat
- Gregor Mendel Institute of Molecular Plant Biology, Austrian Academy of Sciences, Vienna BioCenter, Vienna1030, Austria
| | - Zsuzsanna Mérai
- Gregor Mendel Institute of Molecular Plant Biology, Austrian Academy of Sciences, Vienna BioCenter, Vienna1030, Austria
| | - Thomas Lendl
- Research Institute of Molecular Pathology, Vienna BioCenter, Vienna1030, Austria
| | - Stuart MacFarlane
- The James Hutton Institute, Invergowrie, ScotlandDD25DA, United Kingdom
| | - Michael Nodine
- Department of Plant Sciences, Laboratory of Molecular Biology, Wageningen University and Research, Wageningen6700 AP, The Netherlands
| | - Ortrun Mittelsten Scheid
- Gregor Mendel Institute of Molecular Plant Biology, Austrian Academy of Sciences, Vienna BioCenter, Vienna1030, Austria
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6
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Yang DL, Huang K, Deng D, Zeng Y, Wang Z, Zhang Y. DNA-dependent RNA polymerases in plants. THE PLANT CELL 2023; 35:3641-3661. [PMID: 37453082 PMCID: PMC10533338 DOI: 10.1093/plcell/koad195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 06/09/2023] [Accepted: 05/29/2023] [Indexed: 07/18/2023]
Abstract
DNA-dependent RNA polymerases (Pols) transfer the genetic information stored in genomic DNA to RNA in all organisms. In eukaryotes, the typical products of nuclear Pol I, Pol II, and Pol III are ribosomal RNAs, mRNAs, and transfer RNAs, respectively. Intriguingly, plants possess two additional Pols, Pol IV and Pol V, which produce small RNAs and long noncoding RNAs, respectively, mainly for silencing transposable elements. The five plant Pols share some subunits, but their distinct functions stem from unique subunits that interact with specific regulatory factors in their transcription cycles. Here, we summarize recent advances in our understanding of plant nucleus-localized Pols, including their evolution, function, structures, and transcription cycles.
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Affiliation(s)
- Dong-Lei Yang
- National Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Nanjing 210095, China
| | - Kun Huang
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Deyin Deng
- State Key Laboratory of Subtropical Silviculture, School of Forestry and Biotechnology, Zhejiang Agriculture and Forestry University, Lin’an, Hangzhou 311300, China
| | - Yuan Zeng
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Zhenxing Wang
- College of Horticulture, National Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Nanjing 210095, China
| | - Yu Zhang
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
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7
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Jiang C, Li Z, Zheng L, Yu Y, Niu D. Small RNAs: Efficient and miraculous effectors that play key roles in plant-microbe interactions. MOLECULAR PLANT PATHOLOGY 2023; 24:999-1013. [PMID: 37026481 PMCID: PMC10346379 DOI: 10.1111/mpp.13329] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 03/06/2023] [Accepted: 03/07/2023] [Indexed: 06/19/2023]
Abstract
Plants' response to pathogens is highly complex and involves changes at different levels, such as activation or repression of a vast array of genes. Recently, many studies have demonstrated that many RNAs, especially small RNAs (sRNAs), are involved in genetic expression and reprogramming affecting plant-pathogen interactions. The sRNAs, including short interfering RNAs and microRNAs, are noncoding RNA with 18-30 nucleotides, and are recognized as key genetic and epigenetic regulators. In this review, we summarize the new findings about defence-related sRNAs in the response to pathogens and our current understanding of their effects on plant-pathogen interactions. The main content of this review article includes the roles of sRNAs in plant-pathogen interactions, cross-kingdom sRNA trafficking between host and pathogen, and the application of RNA-based fungicides for plant disease control.
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Affiliation(s)
- Chun‐Hao Jiang
- Department of Plant Pathology, College of Plant ProtectionNanjing Agricultural UniversityNanjingChina
- Key Laboratory of Integrated Management of Crop Disease and Pests, Ministry of Education/Key Laboratory of Integrated Pest Management on Crops in East China, Ministry of Agriculture/Key Laboratory of Plant ImmunityNanjing Agricultural UniversityNanjingChina
- Engineering Center of Bioresource Pesticide in Jiangsu ProvinceNanjingChina
| | - Zi‐Jie Li
- Department of Plant Pathology, College of Plant ProtectionNanjing Agricultural UniversityNanjingChina
- Key Laboratory of Integrated Management of Crop Disease and Pests, Ministry of Education/Key Laboratory of Integrated Pest Management on Crops in East China, Ministry of Agriculture/Key Laboratory of Plant ImmunityNanjing Agricultural UniversityNanjingChina
- Engineering Center of Bioresource Pesticide in Jiangsu ProvinceNanjingChina
| | - Li‐Yu Zheng
- Department of Plant Pathology, College of Plant ProtectionNanjing Agricultural UniversityNanjingChina
- Key Laboratory of Integrated Management of Crop Disease and Pests, Ministry of Education/Key Laboratory of Integrated Pest Management on Crops in East China, Ministry of Agriculture/Key Laboratory of Plant ImmunityNanjing Agricultural UniversityNanjingChina
- Engineering Center of Bioresource Pesticide in Jiangsu ProvinceNanjingChina
| | - Yi‐Yang Yu
- Department of Plant Pathology, College of Plant ProtectionNanjing Agricultural UniversityNanjingChina
- Key Laboratory of Integrated Management of Crop Disease and Pests, Ministry of Education/Key Laboratory of Integrated Pest Management on Crops in East China, Ministry of Agriculture/Key Laboratory of Plant ImmunityNanjing Agricultural UniversityNanjingChina
- Engineering Center of Bioresource Pesticide in Jiangsu ProvinceNanjingChina
| | - Dong‐Dong Niu
- Department of Plant Pathology, College of Plant ProtectionNanjing Agricultural UniversityNanjingChina
- Key Laboratory of Integrated Management of Crop Disease and Pests, Ministry of Education/Key Laboratory of Integrated Pest Management on Crops in East China, Ministry of Agriculture/Key Laboratory of Plant ImmunityNanjing Agricultural UniversityNanjingChina
- Engineering Center of Bioresource Pesticide in Jiangsu ProvinceNanjingChina
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8
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Malavika M, Prakash V, Chakraborty S. Recovery from virus infection: plant's armory in action. PLANTA 2023; 257:103. [PMID: 37115475 DOI: 10.1007/s00425-023-04137-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Accepted: 04/14/2023] [Indexed: 05/26/2023]
Abstract
MAIN CONCLUSION This review focuses on different factors involved in promoting symptom recovery in plants post-virus infection such as epigenetics, transcriptional reprogramming, phytohormones with an emphasis on RNA silencing as well as role of abiotic factors such as temperature on symptom recovery. Plants utilize several different strategies to defend themselves in the battle against invading viruses. Most of the viral proteins interact with plant proteins and interfere with molecular dynamics in a cell which eventually results in symptom development. This initial symptom development is countered by the plant utilizing various factors including the plant's adaptive immunity to develop a virus tolerant state. Infected plants can specifically target and impede the transcription of viral genes as well as degrade the viral transcripts to restrict their proliferation by the production of small-interfering RNA (siRNA) generated from the viral nucleic acid, known as virus-derived siRNA (vsiRNA). To further escalate the degradation of viral nucleic acid, secondary siRNAs are generated. The production of virus-activated siRNA (vasiRNA) from the host genome causes differential regulation of the host transcriptome which plays a major role in establishing a virus tolerant state within the infected plant. The systemic action of vsiRNAs, vasiRNA, and secondary siRNAs with the help of defense hormones like salicylic acid can curb viral proliferation, and thus the newly emerged leaves develop fewer symptoms, maintaining a state of tolerance.
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Affiliation(s)
- M Malavika
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Ved Prakash
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India
- Department of Plant Pathology, Kansas State University, Manhattan, KS, 66506, USA
| | - Supriya Chakraborty
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India.
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Genome-wide identification, characterization and expression analysis of AGO, DCL, and RDR families in Chenopodium quinoa. Sci Rep 2023; 13:3647. [PMID: 36871121 PMCID: PMC9985633 DOI: 10.1038/s41598-023-30827-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 03/02/2023] [Indexed: 03/06/2023] Open
Abstract
RNA interference is a highly conserved mechanism wherein several types of non-coding small RNAs regulate gene expression at the transcriptional or post-transcriptional level, modulating plant growth, development, antiviral defence, and stress responses. Argonaute (AGO), DCL (Dicer-like), and RNA-dependent RNA polymerase (RDR) are key proteins in this process. Here, these three protein families were identified in Chenopodium quinoa. Further, their phylogenetic relationships with Arabidopsis, their domains, three-dimensional structure modelling, subcellular localization, and functional annotation and expression were analysed. Whole-genome sequence analysis predicted 21 CqAGO, eight CqDCL, and 11 CqRDR genes in quinoa. All three protein families clustered into phylogenetic clades corresponding to those of Arabidopsis, including three AGO clades, four DCL clades, and four RDR clades, suggesting evolutionary conservation. Domain and protein structure analyses of the three gene families showed almost complete homogeneity among members of the same group. Gene ontology annotation revealed that the predicted gene families might be directly involved in RNAi and other important pathways. Largely, these gene families showed significant tissue-specific expression patterns, RNA-sequencing (RNA-seq) data revealed that 20 CqAGO, seven CqDCL, and ten CqRDR genes tended to have preferential expression in inflorescences. Most of them being downregulated in response to drought, cold, salt and low phosphate stress. To our knowledge, this is the first study to elucidate these key protein families involved in the RNAi pathway in quinoa, which are significant for understanding the mechanisms underlying stress responses in this plant.
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10
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Du X, Yang Z, Ariza AJF, Wang Q, Xie G, Li S, Du J. Structure of plant RNA-DEPENDENT RNA POLYMERASE 2, an enzyme involved in small interfering RNA production. THE PLANT CELL 2022; 34:2140-2149. [PMID: 35188193 PMCID: PMC9134047 DOI: 10.1093/plcell/koac067] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 02/10/2022] [Indexed: 06/14/2023]
Abstract
In plants, the biogenesis of small interfering RNA (siRNA) requires a family of RNA-dependent RNA polymerases that convert single-stranded RNA (ssRNA) into double-stranded RNA (dsRNA), which is subsequently cleaved into defined lengths by Dicer endonucleases. Here, we determined the structure of maize (Zea mays) RNA-DEPENDENT RNA POLYMERASE 2 (ZmRDR2) in the closed and open conformations. The core catalytic region of ZmRDR2 possesses the canonical DNA-dependent RNA polymerase (DdRP) catalytic sites, pointing to a shared RNA production mechanism between DdRPs and plant RDR-family proteins. Apo-ZmRDR2 adopts a highly compact structure, representing an inactive closed conformation. By contrast, adding RNA induced a significant conformational change in the ZmRDR2 Head domain that opened the RNA binding tunnel, suggesting this is an active elongation conformation of ZmRDR2. Overall, our structural studies trapped both the active and inactive conformations of ZmRDR2, providing insights into the molecular mechanism of dsRNA synthesis during plant siRNA production.
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Affiliation(s)
| | | | - Alfredo Jose Florez Ariza
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, California 94720, USA
- Biophysics Graduate Group, University of California, Berkeley, California 94720, USA
| | - Qian Wang
- Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Institute of Plant and Food Science, Department of Biology, School of Life Science, Southern University of Science and Technology, Shenzhen 518055, China
| | - Guohui Xie
- Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Institute of Plant and Food Science, Department of Biology, School of Life Science, Southern University of Science and Technology, Shenzhen 518055, China
| | - Sisi Li
- Department of Biochemistry and Molecular Biology, International Cancer Center, Shenzhen University Health Science Center, Shenzhen 518060, China
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11
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Fukudome A, Singh J, Mishra V, Reddem E, Martinez-Marquez F, Wenzel S, Yan R, Shiozaki M, Yu Z, Wang JCY, Takagi Y, Pikaard CS. Structure and RNA template requirements of Arabidopsis RNA-DEPENDENT RNA POLYMERASE 2. Proc Natl Acad Sci U S A 2021; 118:e2115899118. [PMID: 34903670 PMCID: PMC8713982 DOI: 10.1073/pnas.2115899118] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/28/2021] [Indexed: 01/18/2023] Open
Abstract
RNA-dependent RNA polymerases play essential roles in RNA-mediated gene silencing in eukaryotes. In Arabidopsis, RNA-DEPENDENT RNA POLYMERASE 2 (RDR2) physically interacts with DNA-dependent NUCLEAR RNA POLYMERASE IV (Pol IV) and their activities are tightly coupled, with Pol IV transcriptional arrest, induced by the nontemplate DNA strand, somehow enabling RDR2 to engage Pol IV transcripts and generate double-stranded RNAs. The double-stranded RNAs are then released from the Pol IV-RDR2 complex and diced into short-interfering RNAs that guide RNA-directed DNA methylation and silencing. Here we report the structure of full-length RDR2, at an overall resolution of 3.1 Å, determined by cryoelectron microscopy. The N-terminal region contains an RNA-recognition motif adjacent to a positively charged channel that leads to a catalytic center with striking structural homology to the catalytic centers of multisubunit DNA-dependent RNA polymerases. We show that RDR2 initiates 1 to 2 nt internal to the 3' ends of its templates and can transcribe the RNA of an RNA/DNA hybrid, provided that 9 or more nucleotides are unpaired at the RNA's 3' end. Using a nucleic acid configuration that mimics the arrangement of RNA and DNA strands upon Pol IV transcriptional arrest, we show that displacement of the RNA 3' end occurs as the DNA template and nontemplate strands reanneal, enabling RDR2 transcription. These results suggest a model in which Pol IV arrest and backtracking displaces the RNA 3' end as the DNA strands reanneal, allowing RDR2 to engage the RNA and synthesize the complementary strand.
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Affiliation(s)
- Akihito Fukudome
- HHMI, Indiana University, Bloomington, IN 47405
- Department of Biology, Indiana University, Bloomington, IN 47405
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405
| | - Jasleen Singh
- Department of Biology, Indiana University, Bloomington, IN 47405
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405
| | - Vibhor Mishra
- HHMI, Indiana University, Bloomington, IN 47405
- Department of Biology, Indiana University, Bloomington, IN 47405
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405
| | - Eswar Reddem
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 47405
| | - Francisco Martinez-Marquez
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 47405
| | - Sabine Wenzel
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 47405
| | - Rui Yan
- CryoEM Facility, Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, VA 20147
| | - Momoko Shiozaki
- CryoEM Facility, Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, VA 20147
| | - Zhiheng Yu
- CryoEM Facility, Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, VA 20147
| | - Joseph Che-Yen Wang
- Indiana University Electron Microscopy Center, Indiana University, Bloomington, IN 47405
| | - Yuichiro Takagi
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 47405;
| | - Craig S Pikaard
- HHMI, Indiana University, Bloomington, IN 47405;
- Department of Biology, Indiana University, Bloomington, IN 47405
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405
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12
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Jha V, Narjala A, Basu D, T. N. S, Pachamuthu K, Chenna S, Nair A, Shivaprasad PV. Essential role of γ-clade RNA-dependent RNA polymerases in rice development and yield-related traits is linked to their atypical polymerase activities regulating specific genomic regions. THE NEW PHYTOLOGIST 2021; 232:1674-1691. [PMID: 34449900 PMCID: PMC9290346 DOI: 10.1111/nph.17700] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 08/14/2021] [Indexed: 05/31/2023]
Abstract
RNA-dependent RNA polymerases (RDR) generate double-stranded (ds)RNA triggers for RNA silencing across eukaryotes. Among the three clades, α-clade and β-clade members are key components of RNA silencing and mediators of stress responses across eukaryotes. However, γ-clade members are unusual in that they are represented in phylogenetically distant plants and fungi, and their functions are unknown. Using genetic, bioinformatic and biochemical methods, we show that γ-clade RDRs from Oryza sativa L. are involved in plant development as well as regulation of expression of coding and noncoding RNAs. Overexpression of γ-clade RDRs in transgenic rice and tobacco plants resulted in robust growth phenotype, whereas their silencing in rice displayed strong inhibition of growth. Small (s)RNA and RNA-seq analysis of OsRDR3 mis-expression lines suggested that it is specifically involved in the regulation of repeat-rich regions in the genome. Biochemical analysis confirmed that OsRDR3 has robust polymerase activities on both single stranded (ss)RNA and ssDNA templates similar to the activities reported for α-clade RDRs such as AtRDR6. Our results provide the first evidence of the importance of γ-clade RDRs in plant development, their atypical biochemical activities and their contribution to the regulation of gene expression.
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Affiliation(s)
- Vikram Jha
- National Centre for Biological SciencesGKVK CampusBangalore560065India
- BIOSS Centre for Biological Signaling StudiesFaculty of BiologyAlbert‐Ludwigs‐Universität FreiburgFreiburg im Breisgau79104Germany
| | - Anushree Narjala
- National Centre for Biological SciencesGKVK CampusBangalore560065India
- SASTRA UniversityThirumalaisamudram, Thanjavur613401India
| | - Debjani Basu
- National Centre for Biological SciencesGKVK CampusBangalore560065India
| | - Sujith T. N.
- National Centre for Biological SciencesGKVK CampusBangalore560065India
- University of Trans‐Disciplinary Health Sciences and TechnologyBengaluru560064India
| | - Kannan Pachamuthu
- National Centre for Biological SciencesGKVK CampusBangalore560065India
- Institut Jean‐Pierre BourginINRAEAgroParisTechUniversité Paris‐SaclayVersailles78000France
| | - Swetha Chenna
- National Centre for Biological SciencesGKVK CampusBangalore560065India
- SASTRA UniversityThirumalaisamudram, Thanjavur613401India
| | - Ashwin Nair
- National Centre for Biological SciencesGKVK CampusBangalore560065India
- SASTRA UniversityThirumalaisamudram, Thanjavur613401India
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13
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Mosharaf MP, Rahman H, Ahsan MA, Akond Z, Ahmed FF, Islam MM, Moni MA, Mollah MNH. In silico identification and characterization of AGO, DCL and RDR gene families and their associated regulatory elements in sweet orange (Citrus sinensis L.). PLoS One 2020; 15:e0228233. [PMID: 33347517 PMCID: PMC7751981 DOI: 10.1371/journal.pone.0228233] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 12/07/2020] [Indexed: 12/30/2022] Open
Abstract
RNA interference (RNAi) plays key roles in post-transcriptional and chromatin modification levels as well as regulates various eukaryotic gene expressions which are involved in stress responses, development and maintenance of genome integrity during developmental stages. The whole mechanism of RNAi pathway is directly involved with the gene-silencing process by the interaction of Dicer-Like (DCL), Argonaute (AGO) and RNA-dependent RNA polymerase (RDR) gene families and their regulatory elements. However, these RNAi gene families and their sub-cellular locations, functional pathways and regulatory components were not extensively investigated in the case of economically and nutritionally important fruit plant sweet orange (Citrus sinensis L.). Therefore, in silico characterization, gene diversity and regulatory factor analysis of RNA silencing genes in C. sinensis were conducted by using the integrated bioinformatics approaches. Genome-wide comparison analysis based on phylogenetic tree approach detected 4 CsDCL, 8 CsAGO and 4 CsRDR as RNAi candidate genes in C. sinensis corresponding to the RNAi genes of model plant Arabidopsis thaliana. The domain and motif composition and gene structure analyses for all three gene families exhibited almost homogeneity within the same group members. The Gene Ontology enrichment analysis clearly indicated that the predicted genes have direct involvement into the gene-silencing and other important pathways. The key regulatory transcription factors (TFs) MYB, Dof, ERF, NAC, MIKC_MADS, WRKY and bZIP were identified by their interaction network analysis with the predicted genes. The cis-acting regulatory elements associated with the predicted genes were detected as responsive to light, stress and hormone functions. Furthermore, the expressed sequence tag (EST) analysis showed that these RNAi candidate genes were highly expressed in fruit and leaves indicating their organ specific functions. Our genome-wide comparison and integrated bioinformatics analyses provided some necessary information about sweet orange RNA silencing components that would pave a ground for further investigation of functional mechanism of the predicted genes and their regulatory factors.
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Affiliation(s)
- Md. Parvez Mosharaf
- Bioinformatics Laboratory, Department of Statistics, University of Rajshahi, Rajshahi, Bangladesh
| | - Hafizur Rahman
- Department of Microbiology, Rajshahi Institute of Biosciences, University of Rajshahi, Rajshahi, Bangladesh
| | - Md. Asif Ahsan
- Bioinformatics Laboratory, Department of Statistics, University of Rajshahi, Rajshahi, Bangladesh
| | - Zobaer Akond
- Bioinformatics Laboratory, Department of Statistics, University of Rajshahi, Rajshahi, Bangladesh
- Institute of Environmental Science, University of Rajshahi, Rajshahi, Bangladesh
- Agricultural Statistics and ICT Division, Bangladesh Agricultural Research Institute (BARI), Gazipur, Bangladesh
| | - Fee Faysal Ahmed
- Bioinformatics Laboratory, Department of Statistics, University of Rajshahi, Rajshahi, Bangladesh
- Department of Mathematics, Jashore University of Science and Technology, Jashore, Bangladesh
| | - Md. Mazharul Islam
- Bioinformatics Laboratory, Department of Statistics, University of Rajshahi, Rajshahi, Bangladesh
| | - Mohammad Ali Moni
- The University of Sydney, Sydney Medical School, School of Medical Sciences, Discipline of Biomedical Science, Sydney, New South Wales, Australia
| | - Md. Nurul Haque Mollah
- Bioinformatics Laboratory, Department of Statistics, University of Rajshahi, Rajshahi, Bangladesh
- * E-mail:
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14
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Prakash V, Singh A, Singh AK, Dalmay T, Chakraborty S. Tobacco RNA-dependent RNA polymerase 1 affects the expression of defence-related genes in Nicotiana benthamiana upon Tomato leaf curl Gujarat virus infection. PLANTA 2020; 252:11. [PMID: 32613448 DOI: 10.1007/s00425-020-03417-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 06/26/2020] [Indexed: 05/25/2023]
Abstract
MAIN CONCLUSION RNA-dependent RNA polymerase 1 of Nicotiana tabacum modulates ToLCGV pathogenesis by influencing a number of defence-related genes in N. benthamiana plants. Key means of plants protecting themselves from the invading viruses is through RNA silencing. RNA-dependent RNA polymerase-1 (RDR1) is one of the crucial proteins of the RNA silencing pathway, which is induced after infection by viruses. RDR1 functions in the generation of small interfering RNAs (siRNAs) against the viral genome, thus it is antiviral in nature. Here, we used the transgenic Nicotiana benthamiana plant expressing N. tabacum NtRDR1 and observed reduced susceptibility towards Tomato leaf curl Gujarat virus (ToLCGV) infection compared to the wild-type N. benthamiana plants. To understand the reason for such reduced susceptibility, we prepared high-definition small RNA (sRNA) cDNA libraries from ToLCGV-infected wild-type N. benthamiana and NtRDR1 expressing N. benthamiana lines and carried out next-generation sequencing (NGS). We found that upon ToLCGV infection the majority of siRNAs generated from the host genome were of the 24 nucleotide (nt) class, while viral siRNAs (vsiRNAs) were of the 21-22-nt class, indicating that transcriptional gene silencing (TGS) is the major pathway for silencing of host genes while viral genes are silenced, predominantly, by post transcriptional gene silencing (PTGS) pathways. We estimated the changes in the expression of various defence-related genes, such as Constitutively Photomorphogenic-9 (COP9) signalosome (CSN) complex subunit-7, Pentatricopeptide repeat containing protein (PPRP), Laccase-3, Glutathione peroxidase-1 (GPX-1), Universal stress protein (USP) A-like protein, Heat shock transcription factor B4 (HSTF-B4), Auxin response factor-18 (ARF18), WRKY-6 and Short chain dehydrogenase reductase-3a. The differential expression of these genes might be linked with the enhanced tolerance of NtRDR1 N. benthamiana transgenic plants to ToLCGV. Our study suggests that reduced expression of subunit-7 of CSN complex and WRKY6, and increased expression of USPA-like protein might be linked with the reduced susceptibility of NtRDR1-transgenic N. benthamiana plants to ToLCGV.
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Affiliation(s)
- Ved Prakash
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
- School of Biological Sciences, University of East Anglia, Norwich, UK
| | - Archana Singh
- School of Biological Sciences, University of East Anglia, Norwich, UK
- Earlham Institute, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Ashish Kumar Singh
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Tamas Dalmay
- School of Biological Sciences, University of East Anglia, Norwich, UK
| | - Supriya Chakraborty
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India.
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15
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Tiwari B, Habermann K, Arif MA, Weil HL, Garcia-Molina A, Kleine T, Mühlhaus T, Frank W. Identification of small RNAs during cold acclimation in Arabidopsis thaliana. BMC PLANT BIOLOGY 2020; 20:298. [PMID: 32600430 PMCID: PMC7325139 DOI: 10.1186/s12870-020-02511-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 06/22/2020] [Indexed: 05/21/2023]
Abstract
BACKGROUND Cold stress causes dynamic changes in gene expression that are partially caused by small non-coding RNAs since they regulate protein coding transcripts and act in epigenetic gene silencing pathways. Thus, a detailed analysis of transcriptional changes of small RNAs (sRNAs) belonging to all known sRNA classes such as microRNAs (miRNA) and small interfering RNA (siRNAs) in response to cold contributes to an understanding of cold-related transcriptome changes. RESULT We subjected A. thaliana plants to cold acclimation conditions (4 °C) and analyzed the sRNA transcriptomes after 3 h, 6 h and 2 d. We found 93 cold responsive differentially expressed miRNAs and only 14 of these were previously shown to be cold responsive. We performed miRNA target prediction for all differentially expressed miRNAs and a GO analysis revealed the overrepresentation of miRNA-targeted transcripts that code for proteins acting in transcriptional regulation. We also identified a large number of differentially expressed cis- and trans-nat-siRNAs, as well as sRNAs that are derived from long non-coding RNAs. By combining the results of sRNA and mRNA profiling with miRNA target predictions and publicly available information on transcription factors, we reconstructed a cold-specific, miRNA and transcription factor dependent gene regulatory network. We verified the validity of links in the network by testing its ability to predict target gene expression under cold acclimation. CONCLUSION In A. thaliana, miRNAs and sRNAs derived from cis- and trans-NAT gene pairs and sRNAs derived from lncRNAs play an important role in regulating gene expression in cold acclimation conditions. This study provides a fundamental database to deepen our knowledge and understanding of regulatory networks in cold acclimation.
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Affiliation(s)
- Bhavika Tiwari
- Department of Biology I, Plant Molecular Cell Biology, Ludwig-Maximilians-Universität München, LMU Biocenter, Großhaderner Str. 2-4, 82152 Planegg-Martinsried, Germany
| | - Kristin Habermann
- Department of Biology I, Plant Molecular Cell Biology, Ludwig-Maximilians-Universität München, LMU Biocenter, Großhaderner Str. 2-4, 82152 Planegg-Martinsried, Germany
| | - M. Asif Arif
- Department of Biology I, Plant Molecular Cell Biology, Ludwig-Maximilians-Universität München, LMU Biocenter, Großhaderner Str. 2-4, 82152 Planegg-Martinsried, Germany
| | - Heinrich Lukas Weil
- Computational Systems Biology, Technische Universität Kaiserslautern, Paul-Ehrlich-Straße 23, 67663 Kaiserslautern, Germany
| | - Antoni Garcia-Molina
- Department of Biology I, Plant Molecular Biology, Ludwig-Maximilians-Universität München, LMU Biocenter, Großhaderner Str. 2-4, 82152 Planegg-Martinsried, Germany
| | - Tatjana Kleine
- Department of Biology I, Plant Molecular Biology, Ludwig-Maximilians-Universität München, LMU Biocenter, Großhaderner Str. 2-4, 82152 Planegg-Martinsried, Germany
| | - Timo Mühlhaus
- Computational Systems Biology, Technische Universität Kaiserslautern, Paul-Ehrlich-Straße 23, 67663 Kaiserslautern, Germany
| | - Wolfgang Frank
- Department of Biology I, Plant Molecular Cell Biology, Ludwig-Maximilians-Universität München, LMU Biocenter, Großhaderner Str. 2-4, 82152 Planegg-Martinsried, Germany
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16
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de Felippes FF, Waterhouse PM. The Whys and Wherefores of Transitivity in Plants. FRONTIERS IN PLANT SCIENCE 2020; 11:579376. [PMID: 32983223 PMCID: PMC7488869 DOI: 10.3389/fpls.2020.579376] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 08/14/2020] [Indexed: 05/05/2023]
Abstract
Transitivity in plants is a mechanism that produces secondary small interfering RNAs (siRNAs) from a transcript targeted by primary small RNAs (sRNAs). It expands the silencing signal to additional sequences of the transcript. The process requires RNA-dependent RNA polymerases (RDRs), which convert single-stranded RNA targets into a double-stranded (ds) RNA, the precursor of siRNAs and is critical for effective and amplified responses to virus infection. It is also important for the production of endogenous secondary siRNAs, such as phased siRNAs (phasiRNAs), which regulate several genes involved in development and adaptation. Transitivity on endogenous transcripts is very specific, utilizing special primary sRNAs, such as miRNAs with unique features, and particular ARGONAUTEs. In contrast, transitivity on transgene and virus (exogenous) transcripts is more generic. This dichotomy of responses implies the existence of a mechanism that differentiates self from non-self targets. In this work, we examine the possible mechanistic process behind the dichotomy and the intriguing counter-intuitive directionality of transitive sequence-spread in plants.
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17
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Zhang Y, Ramming A, Heinke L, Altschmied L, Slotkin RK, Becker JD, Kappel C, Lenhard M. The poly(A) polymerase PAPS1 interacts with the RNA-directed DNA-methylation pathway in sporophyte and pollen development. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2019; 99:655-672. [PMID: 31009115 DOI: 10.1111/tpj.14348] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 03/21/2019] [Accepted: 04/08/2019] [Indexed: 05/28/2023]
Abstract
RNA-based processes play key roles in the regulation of eukaryotic gene expression. This includes both the processing of pre-mRNAs into mature mRNAs ready for translation and RNA-based silencing processes, such as RNA-directed DNA methylation (RdDM). Polyadenylation of pre-mRNAs is one important step in their processing and is carried out by three functionally specialized canonical nuclear poly(A) polymerases in Arabidopsis thaliana. Null mutations in one of these, termed PAPS1, result in a male gametophytic defect. Using a fluorescence-labelling strategy, we have characterized this defect in more detail using RNA and small-RNA sequencing. In addition to global defects in the expression of pollen-differentiation genes, paps1 null-mutant pollen shows a strong overaccumulation of transposable element (TE) transcripts, yet a depletion of 21- and particularly 24-nucleotide-long short interfering RNAs (siRNAs) and microRNAs (miRNAs) targeting the corresponding TEs. Double-mutant analyses support a specific functional interaction between PAPS1 and components of the RdDM pathway, as evident from strong synergistic phenotypes in mutant combinations involving paps1, but not paps2 paps4, mutations. In particular, the double-mutant of paps1 and rna-dependent rna polymerase 6 (rdr6) shows a synergistic developmental phenotype disrupting the formation of the transmitting tract in the female gynoecium. Thus, our findings in A. thaliana uncover a potentially general link between canonical poly(A) polymerases as components of mRNA processing and RdDM, reflecting an analogous interaction in fission yeast.
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Affiliation(s)
- Yunming Zhang
- Institute for Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, D-14476, Potsdam-Golm, Germany
| | - Anna Ramming
- Institute for Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, D-14476, Potsdam-Golm, Germany
| | - Lisa Heinke
- Institute for Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, D-14476, Potsdam-Golm, Germany
| | - Lothar Altschmied
- Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung, Corrensstrasse 3, D-06466 Seeland, OT, Gatersleben, Germany
| | - R Keith Slotkin
- Donald Danforth Plant Science Center, 975 North Warson Road, St Louis, MO, 63132, USA
- Division of Biological Sciences, University of Missouri, Columbia, MO, 65211, USA
| | - Jörg D Becker
- Instituto Gulbenkian de Ciência, Rua da Quinta Grande, 6, 2780-156, Oeiras, Portugal
| | - Christian Kappel
- Institute for Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, D-14476, Potsdam-Golm, Germany
| | - Michael Lenhard
- Institute for Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, D-14476, Potsdam-Golm, Germany
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18
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Prakash V, Chakraborty S. Identification of transcription factor binding sites on promoter of RNA dependent RNA polymerases ( RDRs) and interacting partners of RDR proteins through in silico analysis. PHYSIOLOGY AND MOLECULAR BIOLOGY OF PLANTS : AN INTERNATIONAL JOURNAL OF FUNCTIONAL PLANT BIOLOGY 2019; 25:1055-1071. [PMID: 31402824 PMCID: PMC6656839 DOI: 10.1007/s12298-019-00660-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 12/20/2018] [Accepted: 03/25/2019] [Indexed: 05/14/2023]
Abstract
RNA silencing phenomenon in plants provides resistance to various pathogens and also, it maintains genome integrity. The process of RNA silencing is regulated by diverse proteins, among which RNA dependent RNA polymerases (RDRs) are very crucial for the amplification of small RNAs (sRNAs). Out of various RDR proteins present in plants, role of RDR1, RDR2 and RDR6 for providing resistance against various biotic stresses have been well documented. In contrast, very few information is available regarding the role of RDR3, RDR4 and RDR5 proteins in plant biology and stress response. Furthermore, the regulation of RDRs is not yet known. Here, we have carried out in silico studies for identification of the transcription factor (TF) binding sites on the promoter of RDR1-6 genes of various plant species. Among the TFs predicted to bind on the promoter of RDRs, MYB44, AS1/AS2, WRKY1 are the major one. Furthermore, putative interacting protein partners of RDRs proteins of tomato and rice were also predicted by STRING database which suggests that DCL (Dicer-like) proteins are strong candidate proteins as the interacting partners of RDRs. The knowledge of regulation of RDRs and its interacting protein partners might help in developing resistant plants to biotic stresses.
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Affiliation(s)
- Ved Prakash
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067 India
| | - Supriya Chakraborty
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067 India
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19
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Molecular basis of transitivity in plant RNA silencing. Mol Biol Rep 2019; 46:4645-4660. [DOI: 10.1007/s11033-019-04866-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 05/09/2019] [Indexed: 12/11/2022]
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20
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Islam W, Noman A, Qasim M, Wang L. Plant Responses to Pathogen Attack: Small RNAs in Focus. Int J Mol Sci 2018; 19:E515. [PMID: 29419801 PMCID: PMC5855737 DOI: 10.3390/ijms19020515] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2017] [Revised: 02/04/2018] [Accepted: 02/05/2018] [Indexed: 12/25/2022] Open
Abstract
Small RNAs (sRNA) are a significant group of gene expression regulators for multiple biological processes in eukaryotes. In plants, many sRNA silencing pathways produce extensive array of sRNAs with specialized roles. The evidence on record advocates for the functions of sRNAs during plant microbe interactions. Host sRNAs are reckoned as mandatory elements of plant defense. sRNAs involved in plant defense processes via different pathways include both short interfering RNA (siRNA) and microRNA (miRNA) that actively regulate immunity in response to pathogenic attack via tackling pathogen-associated molecular patterns (PAMPs) and other effectors. In response to pathogen attack, plants protect themselves with the help of sRNA-dependent immune systems. That sRNA-mediated plant defense responses play a role during infections is an established fact. However, the regulations of several sRNAs still need extensive research. In this review, we discussed the topical advancements and findings relevant to pathogen attack and plant defense mediated by sRNAs. We attempted to point out diverse sRNAs as key defenders in plant systems. It is hoped that sRNAs would be exploited as a mainstream player to achieve food security by tackling different plant diseases.
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Affiliation(s)
- Waqar Islam
- College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Ali Noman
- Department of Botany, Government College University, Faisalabad 38040, Pakistan.
- College of Crop Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Muhammad Qasim
- College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Liande Wang
- College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
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21
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Li H, Bowling AJ, Gandra P, Rangasamy M, Pence HE, McEwan RE, Khajuria C, Siegfried BD, Narva KE. Systemic RNAi in western corn rootworm, Diabrotica virgifera virgifera, does not involve transitive pathways. INSECT SCIENCE 2018; 25:45-56. [PMID: 27520841 DOI: 10.1111/1744-7917.12382] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 05/16/2016] [Accepted: 07/12/2016] [Indexed: 06/06/2023]
Abstract
Western corn rootworm (WCR, Diabrotica virgifera virgifera LeConte) is highly sensitive to orally delivered double-stranded RNA (dsRNA). RNAi in WCR is systemic and spreads throughout the insect body. This raises the question whether transitive RNAi is a mechanism that functions in WCR to amplify the RNAi response via production of secondary siRNA. Secondary siRNA production is achieved through RNA-dependent RNA polymerase (RdRP) activity in other eukaryotic organisms, but RdRP has not been identified in WCR and any other insects. This study visualized the spread of the RNAi-mediated knockdown of Dv v-ATPase C mRNA throughout the WCR gut and other tissues using high-sensitivity branched DNA in situ hybridization. Furthermore, we did not detect either secondary siRNA production or transitive RNAi in WCR through siRNA sequence profile analysis. Nucleotide mismatched sequences introduced into either the sense or antisense strand of v-ATPase C dsRNAs were maintained in siRNAs derived from WCR fed with the mismatched dsRNAs in a strand specific manner. The distribution of all siRNAs was restricted to within the original target sequence regions, which may indicate the lack of new dsRNA synthesis leading to production of secondary siRNA. Thus, the systemic spread of RNAi in WCR may be derived from the original dsRNA molecules taken up from the gut lumen. These results indicate that the initial dsRNA dose is important for a lethal systemic RNAi response in WCR and have implications in developing effective dsRNA traits to control WCR and in resistance management to prolong the durability of RNAi trait technology.
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Affiliation(s)
- Huarong Li
- Dow AgroSciences LLC, 9330 Zionsville Rd., Indianapolis, Indiana, USA
| | - Andrew J Bowling
- Dow AgroSciences LLC, 9330 Zionsville Rd., Indianapolis, Indiana, USA
| | - Premchand Gandra
- Dow AgroSciences LLC, 9330 Zionsville Rd., Indianapolis, Indiana, USA
| | | | - Heather E Pence
- Dow AgroSciences LLC, 9330 Zionsville Rd., Indianapolis, Indiana, USA
| | - Robert E McEwan
- Dow AgroSciences LLC, 9330 Zionsville Rd., Indianapolis, Indiana, USA
| | - Chitvan Khajuria
- Department of Entomology, University of Nebraska, Lincoln, Nebraska, USA
- Monsanto Company, Chesterfield, Missouri, USA
| | - Blair D Siegfried
- Entomology and Nematology Department, University of Florida, Gainesville, Florida, USA
| | - Kenneth E Narva
- Dow AgroSciences LLC, 9330 Zionsville Rd., Indianapolis, Indiana, USA
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22
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Baeg K, Tomari Y, Iwakawa HO. In vitro RNA-dependent RNA Polymerase Assay Using Arabidopsis RDR6. Bio Protoc 2018; 8:e2673. [DOI: 10.21769/bioprotoc.2673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 12/13/2017] [Accepted: 12/21/2017] [Indexed: 11/02/2022] Open
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23
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Fishilevich E, Vélez AM, Storer NP, Li H, Bowling AJ, Rangasamy M, Worden SE, Narva KE, Siegfried BD. RNAi as a management tool for the western corn rootworm, Diabrotica virgifera virgifera. PEST MANAGEMENT SCIENCE 2016; 72:1652-1663. [PMID: 27218412 DOI: 10.1002/ps.4324] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2016] [Revised: 04/27/2016] [Accepted: 05/13/2016] [Indexed: 06/05/2023]
Abstract
The western corn rootworm (WCR), Diabrotica virgifera virgifera, is the most important pest of corn in the US Corn Belt. Economic estimates indicate that costs of control and yield loss associated with WCR damage exceed $US 1 billion annually. Historically, corn rootworm management has been extremely difficult because of its ability to evolve resistance to both chemical insecticides and cultural control practices. Since 2003, the only novel commercialized developments in rootworm management have been transgenic plants expressing Bt insecticidal proteins. Four transgenic insecticidal proteins are currently registered for rootworm management, and field resistance to proteins from the Cry3 family highlights the importance of developing traits with new modes of action. One of the newest approaches for controlling rootworm pests involves RNA interference (RNAi). This review describes the current understanding of the RNAi mechanisms in WCR and the use of this technology for WCR management. Further, the review addresses ecological risk assessment of RNAi and insect resistance management of RNAi for corn rootworm. © 2016 Society of Chemical Industry.
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Affiliation(s)
| | - Ana M Vélez
- Department of Entomology, University of Nebraska, Lincoln, NE, USA
| | | | | | | | | | | | | | - Blair D Siegfried
- Entomology and Nematology Department, University of Florida, Gainesville, FL, USA
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Bousios A, Gaut BS. Mechanistic and evolutionary questions about epigenetic conflicts between transposable elements and their plant hosts. CURRENT OPINION IN PLANT BIOLOGY 2016; 30:123-33. [PMID: 26950253 DOI: 10.1016/j.pbi.2016.02.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Revised: 02/16/2016] [Accepted: 02/17/2016] [Indexed: 05/02/2023]
Abstract
Transposable elements (TEs) constitute the majority of plant genomes, but most are epigenetically inactivated by their host. Research over the last decade has elucidated many of the molecular components that are required for TE silencing. In contrast, the evolutionary dynamics between TEs and silencing pathways are less clear. Here, we discuss current information about these dynamics from both mechanistic and evolutionary perspectives. We highlight new evidence that palindromic sequences within TEs may act as signals for host recognition and that cis-regulatory regions of TEs may be sites of ongoing arms races with host defenses. We also discuss patterns of TE aging after they are silenced; while there is not yet a consensus, it appears that TEs are removed more rapidly near genes, such that older TE insertions tend to be farther from genes. We conclude by discussing the energetic costs for maintaining silencing pathways, which appear to be substantive. The maintenance of silencing pathways across many species suggests that epigenetic emergencies are frequent.
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Affiliation(s)
| | - Brandon S Gaut
- Department of Ecology and Evolutionary Biology, UC Irvine, Irvine, CA 92697, USA.
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Qian X, Hamid FM, El Sahili A, Darwis DA, Wong YH, Bhushan S, Makeyev EV, Lescar J. Functional Evolution in Orthologous Cell-encoded RNA-dependent RNA Polymerases. J Biol Chem 2016; 291:9295-309. [PMID: 26907693 PMCID: PMC4861493 DOI: 10.1074/jbc.m115.685933] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Indexed: 12/15/2022] Open
Abstract
Many eukaryotic organisms encode more than one RNA-dependent RNA polymerase (RdRP) that probably emerged as a result of gene duplication. Such RdRP paralogs often participate in distinct RNA silencing pathways and show characteristic repertoires of enzymatic activities in vitro However, to what extent members of individual paralogous groups can undergo functional changes during speciation remains an open question. We show that orthologs of QDE-1, an RdRP component of the quelling pathway in Neurospora crassa, have rapidly diverged in evolution at the amino acid sequence level. Analyses of purified QDE-1 polymerases from N. crassa (QDE-1(Ncr)) and related fungi, Thielavia terrestris (QDE-1(Tte)) and Myceliophthora thermophila (QDE-1(Mth)), show that all three enzymes can synthesize RNA, but the precise modes of their action differ considerably. Unlike their QDE-1(Ncr) counterpart favoring processive RNA synthesis, QDE-1(Tte) and QDE-1(Mth) produce predominantly short RNA copies via primer-independent initiation. Surprisingly, a 3.19 Å resolution crystal structure of QDE-1(Tte) reveals a quasisymmetric dimer similar to QDE-1(Ncr) Further electron microscopy analyses confirm that QDE-1(Tte) occurs as a dimer in solution and retains this status upon interaction with a template. We conclude that divergence of orthologous RdRPs can result in functional innovation while retaining overall protein fold and quaternary structure.
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Affiliation(s)
- Xinlei Qian
- From the Division of Structural Biology and Biochemistry, School of Biological Sciences, Nanyang Technological University, 138673 Singapore, Singapore
| | - Fursham M Hamid
- From the Division of Structural Biology and Biochemistry, School of Biological Sciences, Nanyang Technological University, 138673 Singapore, Singapore
| | - Abbas El Sahili
- From the Division of Structural Biology and Biochemistry, School of Biological Sciences, Nanyang Technological University, 138673 Singapore, Singapore
| | - Dina Amallia Darwis
- From the Division of Structural Biology and Biochemistry, School of Biological Sciences, Nanyang Technological University, 138673 Singapore, Singapore
| | - Yee Hwa Wong
- From the Division of Structural Biology and Biochemistry, School of Biological Sciences, Nanyang Technological University, 138673 Singapore, Singapore
| | - Shashi Bhushan
- From the Division of Structural Biology and Biochemistry, School of Biological Sciences, Nanyang Technological University, 138673 Singapore, Singapore
| | - Eugene V Makeyev
- From the Division of Structural Biology and Biochemistry, School of Biological Sciences, Nanyang Technological University, 138673 Singapore, Singapore, the Medical Research Council Centre for Developmental Neurobiology, King's College, London SE1 1UL, United Kingdom, and
| | - Julien Lescar
- From the Division of Structural Biology and Biochemistry, School of Biological Sciences, Nanyang Technological University, 138673 Singapore, Singapore, UPMC UMRS CR7-CNRS ERL 8255-INSERM U1135 Centre d' Immunologie et des Maladies Infectieuses, Faculté de Médecine Pierre et Marie Curie, Centre Hospitalier Universitaire Pitié-Salpêtrière, 75031 Paris, France
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