1
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Zhao Q, Pavanello L, Bartlam M, Winkler GS. Structure and function of molecular machines involved in deadenylation-dependent 5'-3' mRNA degradation. Front Genet 2023; 14:1233842. [PMID: 37876592 PMCID: PMC10590902 DOI: 10.3389/fgene.2023.1233842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 09/25/2023] [Indexed: 10/26/2023] Open
Abstract
In eukaryotic cells, the synthesis, processing, and degradation of mRNA are important processes required for the accurate execution of gene expression programmes. Fully processed cytoplasmic mRNA is characterised by the presence of a 5'cap structure and 3'poly(A) tail. These elements promote translation and prevent non-specific degradation. Degradation via the deadenylation-dependent 5'-3' degradation pathway can be induced by trans-acting factors binding the mRNA, such as RNA-binding proteins recognising sequence elements and the miRNA-induced repression complex. These factors recruit the core mRNA degradation machinery that carries out the following steps: i) shortening of the poly(A) tail by the Ccr4-Not and Pan2-Pan3 poly (A)-specific nucleases (deadenylases); ii) removal of the 5'cap structure by the Dcp1-Dcp2 decapping complex that is recruited by the Lsm1-7-Pat1 complex; and iii) degradation of the mRNA body by the 5'-3' exoribonuclease Xrn1. In this review, the biochemical function of the nucleases and accessory proteins involved in deadenylation-dependent mRNA degradation will be reviewed with a particular focus on structural aspects of the proteins and enzymes involved.
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Affiliation(s)
- Qi Zhao
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai International Advanced Research Institute (Shenzhen Futian), Nankai University, Tianjin, China
| | - Lorenzo Pavanello
- School of Pharmacy, University of Nottingham, University Park, Nottingham, United Kingdom
| | - Mark Bartlam
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai International Advanced Research Institute (Shenzhen Futian), Nankai University, Tianjin, China
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2
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Chen T, Yuan H, Qiao H, Jiang S, Zhang W, Xiong Y, Fu H, Jin S. Mn-XRN1 Has an Inhibitory Effect on Ovarian Reproduction in Macrobrachium nipponense. Genes (Basel) 2023; 14:1454. [PMID: 37510358 PMCID: PMC10380074 DOI: 10.3390/genes14071454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 07/13/2023] [Accepted: 07/14/2023] [Indexed: 07/30/2023] Open
Abstract
XRN1 is an exoribonuclease that degrades mRNA in the cytoplasm along the 5'-3' direction. A previous study indicated that it may be involved in the reproduction of Macrobrachium nipponense. Quantitative real-time PCR was used to detect the spatiotemporal expression pattern of Mn-XRN1. At the tissue level, Mn-XRN1 was significantly expressed in the ovary. During development, Mn-XRN1 was significantly expressed at the CS stage of the embryo, on the 10th day post-larval and in the O2 stage of ovarian reproduction. The in situ hybridization results showed the location of Mn-XRN1 in the ovary. The expression of Mn-VASA was significantly increased after in vivo injection of Mn-XRN1 dsRNA. This suggests that Mn-XRN1 negatively regulates the expression of Mn-VASA. Furthermore, we counted the number of M. nipponense at various stages of ovarian reproduction on different days after RNAi. The results showed that ovarian development was significantly accelerated. In general, the results of the present study indicate that Mn-XRN1 has an inhibitory effect on the ovarian maturation of M. nipponense. The inhibitory effect might be through negative regulation of Mn-VASA.
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Affiliation(s)
- Tianyong Chen
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai 201306, China
| | - Huwei Yuan
- Wuxi Fisheries College, Nanjing Agricultural University, Wuxi 214081, China
| | - Hui Qiao
- Key Laboratory of Freshwater Fisheries and Germplasm Resources Utilization, Ministry of Agriculture, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi 214081, China
| | - Sufei Jiang
- Key Laboratory of Freshwater Fisheries and Germplasm Resources Utilization, Ministry of Agriculture, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi 214081, China
| | - Wenyi Zhang
- Key Laboratory of Freshwater Fisheries and Germplasm Resources Utilization, Ministry of Agriculture, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi 214081, China
| | - Yiwei Xiong
- Key Laboratory of Freshwater Fisheries and Germplasm Resources Utilization, Ministry of Agriculture, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi 214081, China
| | - Hongtuo Fu
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai 201306, China
- Key Laboratory of Freshwater Fisheries and Germplasm Resources Utilization, Ministry of Agriculture, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi 214081, China
| | - Shubo Jin
- Key Laboratory of Freshwater Fisheries and Germplasm Resources Utilization, Ministry of Agriculture, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi 214081, China
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3
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Zhang Y, Liang X, Zhao M, Qi T, Guo H, Zhao J, Zhao J, Zhan G, Kang Z, Zheng L. A novel ambigrammatic mycovirus, PsV5, works hand in glove with wheat stripe rust fungus to facilitate infection. PLANT COMMUNICATIONS 2023; 4:100505. [PMID: 36527233 DOI: 10.1016/j.xplc.2022.100505] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 11/16/2022] [Accepted: 12/14/2022] [Indexed: 05/11/2023]
Abstract
Here we describe a novel narnavirus, Puccinia striiformis virus 5 (PsV5), from the devastating wheat stripe rust fungus P. striiformis f. sp. tritici (Pst). The genome of PsV5 contains two predicted open reading frames (ORFs) that largely overlap on reverse strands: an RNA-dependent RNA polymerase (RdRp) and a reverse-frame ORF (rORF) with unknown function. Protein translations of both ORFs were demonstrated by immune technology. Transgenic wheat lines overexpressing PsV5 (RdRp-rORF), RdRp ORF, or rORF were more susceptible to Pst infection, whereas PsV5-RNA interference (RNAi) lines were more resistant. Overexpression of PsV5 (RdRp-rORF), RdRp ORF, or rORF in Fusarium graminearum also boosted fungal virulence. We thus report a novel ambigrammatic mycovirus that promotes the virulence of its fungal host. The results are a significant addition to our understanding of virosphere diversity and offer insights for sustainable wheat rust disease control.
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Affiliation(s)
- Yanhui Zhang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Xiaofei Liang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Mengxin Zhao
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Tuo Qi
- State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China, State Key Laboratory of Hybrid Rice, Key Laboratory of Major Crop Diseases & Collaborative Innovation Center for Hybrid Rice in Yangtze River Basin, Rice Research Institute, Sichuan Agricultural University at Wenjiang, Chengdu, Sichuan 611130, China
| | - Hualong Guo
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Jing Zhao
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Jie Zhao
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Gangming Zhan
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Zhensheng Kang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China.
| | - Li Zheng
- Sanya Nanfan Research Institute of Hainan University, Hainan Yazhou Bay Seed Laboratory, Sanya 572025, China; Key Laboratory of Green Prevention and Control of Tropical Plant Diseases and Pests, Ministry of Education and School of Plant Protection, Hainan University, Haikou, Hainan 570228, China.
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4
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Oberlin S, Rajeswaran R, Trasser M, Barragán-Borrero V, Schon MA, Plotnikova A, Loncsek L, Nodine MD, Marí-Ordóñez A, Voinnet O. Innate, translation-dependent silencing of an invasive transposon in Arabidopsis. EMBO Rep 2021; 23:e53400. [PMID: 34931432 PMCID: PMC8892269 DOI: 10.15252/embr.202153400] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 12/05/2021] [Accepted: 12/06/2021] [Indexed: 11/25/2022] Open
Abstract
Co‐evolution between hosts’ and parasites’ genomes shapes diverse pathways of acquired immunity based on silencing small (s)RNAs. In plants, sRNAs cause heterochromatinization, sequence degeneration, and, ultimately, loss of autonomy of most transposable elements (TEs). Recognition of newly invasive plant TEs, by contrast, involves an innate antiviral‐like silencing response. To investigate this response’s activation, we studied the single‐copy element EVADÉ (EVD), one of few representatives of the large Ty1/Copia family able to proliferate in Arabidopsis when epigenetically reactivated. In Ty1/Copia elements, a short subgenomic mRNA (shGAG) provides the necessary excess of structural GAG protein over the catalytic components encoded by the full‐length genomic flGAG‐POL. We show here that the predominant cytosolic distribution of shGAG strongly favors its translation over mostly nuclear flGAG‐POL. During this process, an unusually intense ribosomal stalling event coincides with mRNA breakage yielding unconventional 5’OH RNA fragments that evade RNA quality control. The starting point of sRNA production by RNA‐DEPENDENT‐RNA‐POLYMERASE‐6 (RDR6), exclusively on shGAG, occurs precisely at this breakage point. This hitherto‐unrecognized “translation‐dependent silencing” (TdS) is independent of codon usage or GC content and is not observed on TE remnants populating the Arabidopsis genome, consistent with their poor association, if any, with polysomes. We propose that TdS forms a primal defense against EVD de novo invasions that underlies its associated sRNA pattern.
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Affiliation(s)
- Stefan Oberlin
- Department of Biology, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland
| | - Rajendran Rajeswaran
- Department of Biology, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland
| | - Marieke Trasser
- Gregor Mendel Institute of Molecular Plant Biology (GMI) of the Austrian Academy of Sciences, Vienna, Austria.,Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, Vienna, Austria
| | - Verónica Barragán-Borrero
- Department of Biology, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland.,Gregor Mendel Institute of Molecular Plant Biology (GMI) of the Austrian Academy of Sciences, Vienna, Austria
| | - Michael A Schon
- Gregor Mendel Institute of Molecular Plant Biology (GMI) of the Austrian Academy of Sciences, Vienna, Austria
| | - Alexandra Plotnikova
- Gregor Mendel Institute of Molecular Plant Biology (GMI) of the Austrian Academy of Sciences, Vienna, Austria
| | - Lukas Loncsek
- Gregor Mendel Institute of Molecular Plant Biology (GMI) of the Austrian Academy of Sciences, Vienna, Austria
| | - Michael D Nodine
- Gregor Mendel Institute of Molecular Plant Biology (GMI) of the Austrian Academy of Sciences, Vienna, Austria.,Laboratory of Molecular Biology, Wageningen University, Wageningen, The Netherlands
| | - Arturo Marí-Ordóñez
- Department of Biology, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland.,Gregor Mendel Institute of Molecular Plant Biology (GMI) of the Austrian Academy of Sciences, Vienna, Austria
| | - Olivier Voinnet
- Department of Biology, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland
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5
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RNA Structure Protects the 5'-end of an Uncapped Tombusvirus RNA Genome from Xrn Digestion. J Virol 2021; 95:e0103421. [PMID: 34346764 DOI: 10.1128/jvi.01034-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
One of the many challenges faced by RNA viruses is the maintenance of their genomes during infections of host cells. Members of the family Tombusviridae are plus-strand RNA viruses with unmodified triphosphorylated genomic 5'-termini. The tombusvirus Carnation Italian ringspot virus was used to investigate how it protects its RNA genome from attack by 5'-end-targeting degradation enzymes. In vivo and in vitro assays were employed to determine the role of genomic RNA structure in conferring protection from the 5'-to-3' exoribonuclease Xrn. The results revealed that (i) the CIRV RNA genome is more resistant to Xrn than its sg mRNAs, (ii) the genomic 5'UTR folds into a compact RNA structure that effectively and independently prevents Xrn access, (iii) the RNA structure limiting 5'-access is formed by secondary and tertiary interactions that function cooperatively, (iv) the structure is also able to block access of RNA pyrophosphohydrolase to the genomic 5'-terminus, and (v) the RNA structure does not stall an actively digesting Xrn. Based on its proficiency at impeding Xrn 5'-access, we have termed this 5'-terminal structure an Xrn-evading RNA or xeRNA. These and other findings demonstrate that the 5'UTR of the CIRV RNA genome folds into a complex structural conformation that helps to protect its unmodified 5'-terminus from enzymatic decay during infections. IMPORTANCE The plus-strand RNA genomes of plant viruses in the large family Tombusviridae are not 5'-capped. Here we explored how a species in the type genus Tombusvirus protects its genomic 5'-end from cellular nuclease attack. Our results revealed that the 5'-terminal sequence of the CIRV genome folds into a complex RNA structure that limits access of the 5'-to-3' exoribonuclease Xrn, thereby protecting it from processive degradation. The RNA conformation also impeded access of RNA pyrophosphohydrolase, which converts 5'-triphosphorylated RNA termini into 5'-monophosphorylated forms, the preferred substrate for Xrn. This study represents the first report of a genome-encoded higher-order RNA structure independently conferring resistance to cellular 5'-end-attacking enzymes in an RNA plant virus.
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6
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Athapattu US, Amarasekara CA, Immel JR, Bloom S, Barany F, Nagel AC, Soper SA. Solid-phase XRN1 reactions for RNA cleavage: application in single-molecule sequencing. Nucleic Acids Res 2021; 49:e41. [PMID: 33511416 PMCID: PMC8053086 DOI: 10.1093/nar/gkab001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 12/04/2020] [Accepted: 01/04/2021] [Indexed: 01/29/2023] Open
Abstract
Modifications in RNA are numerous (∼170) and in higher numbers compared to DNA (∼5) making the ability to sequence an RNA molecule to identify these modifications highly tenuous using next generation sequencing (NGS). The ability to immobilize an exoribonuclease enzyme, such as XRN1, to a solid support while maintaining its activity and capability to cleave both the canonical and modified ribonucleotides from an intact RNA molecule can be a viable approach for single-molecule RNA sequencing. In this study, we report an enzymatic reactor consisting of covalently attached XRN1 to a solid support as the groundwork for a novel RNA exosequencing technique. The covalent attachment of XRN1 to a plastic solid support was achieved using EDC/NHS coupling chemistry. Studies showed that the solid-phase digestion efficiency of model RNAs was 87.6 ± 2.8%, while the XRN1 solution-phase digestion for the same model was 78.3 ± 4.4%. The ability of immobilized XRN1 to digest methylated RNA containing m6A and m5C ribonucleotides was also demonstrated. The processivity and clipping rate of immobilized XRN1 secured using single-molecule fluorescence measurements of a single RNA transcript demonstrated a clipping rate of 26 ± 5 nt s-1 and a processivity of >10.5 kb at 25°C.
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Affiliation(s)
| | | | - Jacob R Immel
- Department of Medicinal Chemistry, University of Kansas, Lawrence, KS 66045, USA
| | - Steven Bloom
- Department of Medicinal Chemistry, University of Kansas, Lawrence, KS 66045, USA
| | | | | | - Steven A Soper
- Department of Chemistry, University of Kansas, Lawrence, KS 66045, USA
- Sunflower Genomics, Inc., Lawrence, KS 66047, USA
- Department of Mechanical Engineering and Bioengineering, University of Kansas, Lawrence, KS 66045, USA
- Department of Cancer Biology and KU Cancer Center, University of Kansas Medical Center, Kansas City, KS 66160, USA
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7
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Langeberg CJ, Welch WRW, McGuire JV, Ashby A, Jackson AD, Chapman EG. Biochemical Characterization of Yeast Xrn1. Biochemistry 2020; 59:1493-1507. [PMID: 32251580 DOI: 10.1021/acs.biochem.9b01035] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Messenger RNA degradation is an important component of overall gene expression. During the final step of eukaryotic mRNA degradation, exoribonuclease 1 (Xrn1) carries out 5' → 3' processive, hydrolytic degradation of RNA molecules using divalent metal ion catalysis. To initiate studies of the 5' → 3' RNA decay machinery in our lab, we expressed a C-terminally truncated version of Saccharomyces cerevisiae Xrn1 and explored its enzymology using a second-generation, time-resolved fluorescence RNA degradation assay. Using this system, we quantitatively explored Xrn1's preference for 5'-monophosphorylated RNA substrates, its pH dependence, and the importance of active site mutations in the molecule's conserved catalytic core. Furthermore, we explore Xrn1's preference for RNAs containing a 5' single-stranded region both in an intermolecular hairpin structure and in an RNA-DNA hybrid duplex system. These results both expand and solidify our understanding of Xrn1, a centrally important enzyme whose biochemical properties have implications in numerous RNA degradation and processing pathways.
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Affiliation(s)
- Conner J Langeberg
- Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208, United States
| | - William R W Welch
- Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208, United States
| | - John V McGuire
- Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208, United States
| | - Alison Ashby
- Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208, United States
| | - Alexander D Jackson
- Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208, United States
| | - Erich G Chapman
- Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208, United States
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8
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Wang Q, Mu F, Xie J, Cheng J, Fu Y, Jiang D. A Single ssRNA Segment Encoding RdRp Is Sufficient for Replication, Infection, and Transmission of Ourmia-Like Virus in Fungi. Front Microbiol 2020; 11:379. [PMID: 32256466 PMCID: PMC7093599 DOI: 10.3389/fmicb.2020.00379] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 02/20/2020] [Indexed: 01/07/2023] Open
Abstract
Recently, an increasing number of ourmia-like viruses have been found in fungi; however, the features of these viruses remain unknown. Here, we report a novel ourmia-like virus isolated from Sclerotinia sclerotiorum. This virus, named S. sclerotiorum ourmia-like virus 4 (SsOLV4), has a genome 2,982 nt in length with a G-pentamer (GGGGG) at the 5'-terminus and a C-pentamer (CCCCC) at the 3'-terminus. The SsOLV4 genome has only one large putative open reading frame (ORF) predicted with both standard codes and mitochondrial codes and encodes an RNA-dependent RNA polymerase (RdRp). SsOLV4 is closely phylogenetically related to Pyricularia oryzae ourmia-like virus 1, with 42% identity between the RdRp amino acid sequences. We constructed full-length cDNA of SsOLV4 and synthesized RNA in vitro using the T7 RNA polymerase. The synthesized RNA could transfect S. sclerotiorum protoplasts efficiently. We further found that viral RNA could infect mycelia when mixed with PEG buffer. Our study suggests that a novel genus in family Botourmiaviridae should be established for SsOLV4 and other related viruses and demonstrates that one single-stranded RNA segment encoding RdRp is sufficient for ourmia-like viruses in fungi.
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Affiliation(s)
- Qihua Wang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Plant Pathology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Fan Mu
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Plant Pathology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Jiatao Xie
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Plant Pathology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Jiasen Cheng
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Plant Pathology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Yanping Fu
- Key Laboratory of Plant Pathology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Daohong Jiang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Plant Pathology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
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9
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Gunawardene CD, Newburn LR, White K. A 212-nt long RNA structure in the Tobacco necrosis virus-D RNA genome is resistant to Xrn degradation. Nucleic Acids Res 2019; 47:9329-9342. [PMID: 31392982 PMCID: PMC6755097 DOI: 10.1093/nar/gkz668] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 06/26/2019] [Accepted: 07/25/2019] [Indexed: 12/16/2022] Open
Abstract
Plus-strand RNA viruses can accumulate viral RNA degradation products during infections. Some of these decay intermediates are generated by the cytosolic 5'-to-3' exoribonuclease Xrn1 (mammals and yeast) or Xrn4 (plants) and are formed when the enzyme stalls on substrate RNAs upon encountering inhibitory RNA structures. Many Xrn-generated RNAs correspond to 3'-terminal segments within the 3'-UTR of viral genomes and perform important functions during infections. Here we have investigated a 3'-terminal small viral RNA (svRNA) generated by Xrn during infections with Tobacco necrosis virus-D (family Tombusviridae). Our results indicate that (i) unlike known stalling RNA structures that are compact and modular, the TNV-D structure encompasses the entire 212 nt of the svRNA and is not functionally transposable, (ii) at least two tertiary interactions within the RNA structure are required for effective Xrn blocking and (iii) most of the svRNA generated in infections is derived from viral polymerase-generated subgenomic mRNA1. In vitro and in vivo analyses allowed for inferences on roles for the svRNA. Our findings provide a new and distinct addition to the growing list of Xrn-resistant viral RNAs and stalling structures found associated with different plant and animal RNA viruses.
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Affiliation(s)
| | - Laura R Newburn
- Department of Biology, York University, Toronto, Ontario, M3J 1P3, Canada
| | - K Andrew White
- Department of Biology, York University, Toronto, Ontario, M3J 1P3, Canada
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10
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Cherry PD, White LK, York K, Hesselberth JR. Genetic bypass of essential RNA repair enzymes in budding yeast. RNA (NEW YORK, N.Y.) 2018; 24:313-323. [PMID: 29212664 PMCID: PMC5824351 DOI: 10.1261/rna.061788.117] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 12/04/2017] [Indexed: 05/15/2023]
Abstract
RNA repair enzymes catalyze rejoining of an RNA molecule after cleavage of phosphodiester linkages. RNA repair in budding yeast is catalyzed by two separate enzymes that process tRNA exons during their splicing and HAC1 mRNA exons during activation of the unfolded protein response (UPR). The RNA ligase Trl1 joins 2',3'-cyclic phosphate and 5'-hydroxyl RNA fragments, creating a phosphodiester linkage with a 2'-phosphate at the junction. The 2'-phosphate is removed by the 2'-phosphotransferase Tpt1. We bypassed the essential functions of TRL1 and TPT1 in budding yeast by expressing "prespliced," intronless versions of the 10 normally intron-containing tRNAs, indicating this repair pathway does not have additional essential functions. Consistent with previous studies, expression of intronless tRNAs failed to rescue the growth of cells with deletions in components of the SEN complex, implying an additional essential role for the splicing endonuclease. The trl1Δ and tpt1Δ mutants accumulate tRNA and HAC1 splicing intermediates indicative of RNA repair defects and are hypersensitive to drugs that inhibit translation. Failure to induce the unfolded protein response in trl1Δ cells grown with tunicamycin is lethal owing to their inability to ligate HAC1 after its cleavage by Ire1. In contrast, tpt1Δ mutants grow in the presence of tunicamycin despite reduced accumulation of spliced HAC1 mRNA. We optimized a PCR-based method to detect RNA 2'-phosphate modifications and show they are present on ligated HAC1 mRNA. These RNA repair mutants enable new studies of the role of RNA repair in cellular physiology.
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Affiliation(s)
- Patrick D Cherry
- Department of Biochemistry and Molecular Genetics, Program in Molecular Biology, RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
| | - Laura K White
- Department of Biochemistry and Molecular Genetics, Program in Molecular Biology, RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
| | - Kerri York
- Department of Biochemistry and Molecular Genetics, Program in Molecular Biology, RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
| | - Jay R Hesselberth
- Department of Biochemistry and Molecular Genetics, Program in Molecular Biology, RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
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11
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Kramer S. Simultaneous detection of mRNA transcription and decay intermediates by dual colour single mRNA FISH on subcellular resolution. Nucleic Acids Res 2017; 45:e49. [PMID: 27940558 PMCID: PMC5397161 DOI: 10.1093/nar/gkw1245] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 11/28/2016] [Indexed: 02/06/2023] Open
Abstract
The detection of mRNAs undergoing transcription or decay is challenging, because both processes are fast. However, the relative proportion of an mRNA in synthesis or decay increases with mRNA size and decreases with mRNA half-life. Based on this rationale, I have exploited a 22 200 nucleotide-long, short-lived endogenous mRNA as a reporter for mRNA metabolism in trypanosomes. The extreme 5΄ and 3΄ ends were labeled with red- and green-fluorescent Affymetrix® single mRNA FISH probes, respectively. In the resulting fluorescence images, yellow spots represent intact mRNAs; red spots are mRNAs in transcription or 3΄-5΄ decay, and green spots are mRNAs in 5΄-3΄ degradation. Most red spots were nuclear and insensitive to transcriptional inhibition and thus likely transcription intermediates. Most green spots were cytoplasmic, confirming that the majority of cytoplasmic decay in trypanosomes is 5΄-3΄. The system showed the expected changes at inhibition of transcription or translation and RNAi depletion of the trypanosome homologue to the 5΄-3΄ exoribonuclease Xrn1. The method allows to monitor changes in mRNA metabolism both on cellular and on population/tissue wide levels, but also to study the subcellular localization of mRNA transcription and decay pathways. I show that the system is applicable to mammalian cells.
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Affiliation(s)
- Susanne Kramer
- Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
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12
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Peach SE, York K, Hesselberth JR. Global analysis of RNA cleavage by 5'-hydroxyl RNA sequencing. Nucleic Acids Res 2015; 43:e108. [PMID: 26001965 PMCID: PMC4787814 DOI: 10.1093/nar/gkv536] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 05/10/2015] [Indexed: 11/12/2022] Open
Abstract
RNA cleavage by some endoribonucleases and self-cleaving ribozymes produces RNA fragments with 5′-hydroxyl (5′-OH) and 2′,3′-cyclic phosphate termini. To identify 5′-OH RNA fragments produced by these cleavage events, we exploited the unique ligation mechanism of Escherichia coli RtcB RNA ligase to attach an oligonucleotide linker to RNAs with 5′-OH termini, followed by steps for library construction and analysis by massively parallel DNA sequencing. We applied the method to RNA from budding yeast and captured known 5′-OH fragments produced by tRNA Splicing Endonuclease (SEN) during processing of intron-containing pre-tRNAs and by Ire1 cleavage of HAC1 mRNA following induction of the unfolded protein response (UPR). We identified numerous novel 5′-OH fragments derived from mRNAs: some 5′-OH mRNA fragments were derived from single, localized cleavages, while others were likely produced by multiple, distributed cleavages. Many 5′-OH fragments derived from mRNAs were produced upstream of codons for highly electrostatic peptides, suggesting that the fragments may be generated by co-translational mRNA decay. Several 5′-OH RNA fragments accumulated during the induction of the UPR, some of which share a common sequence motif that may direct cleavage of these mRNAs. This method enables specific capture of 5′-OH termini and complements existing methods for identifying RNAs with 2′,3′-cyclic phosphate termini.
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Affiliation(s)
- Sally E Peach
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA Program in Molecular Biology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Kerri York
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Jay R Hesselberth
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA Program in Molecular Biology, University of Colorado School of Medicine, Aurora, CO 80045, USA
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13
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Raju KK, Natarajan S, Kumar NS, Kumar DA, NM R. Role of cytoplasmic deadenylation and mRNA decay factors in yeast apoptosis. FEMS Yeast Res 2015; 15:fou006. [DOI: 10.1093/femsyr/fou006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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14
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Dougherty JD, Reineke LC, Lloyd RE. mRNA decapping enzyme 1a (Dcp1a)-induced translational arrest through protein kinase R (PKR) activation requires the N-terminal enabled vasodilator-stimulated protein homology 1 (EVH1) domain. J Biol Chem 2013; 289:3936-49. [PMID: 24382890 DOI: 10.1074/jbc.m113.518191] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have shown previously that poliovirus infection disrupts cytoplasmic P-bodies in infected mammalian cells. During the infectious cycle, poliovirus causes the directed cleavage of Dcp1a and Pan3, coincident with the dispersion of P-bodies. We now show that expression of Dcp1a prior to infection, surprisingly, restricts poliovirus infection. This inhibition of infection was independent of P-body formation because expression of GFP-Dcp1a mutants that cannot enter P-bodies restricted poliovirus infection similar to wild-type GFP-Dcp1a. Expression of wild-type or mutant GFP-Dcp1a induced phosphorylation of eIF2α through the eIF2α kinase protein kinase R (PKR). Activation of PKR required the amino-terminal EVH1 domain of Dcp1a. This PKR-induced translational inhibition appears to be specific to Dcp1a because the expression of other P-body components, Pan2, Pan3, Ccr4, or Caf1, did not result in the inhibition of poliovirus gene expression or induce eIF2α phosphorylation. The translation blockade induced by Dcp1a expression suggests novel signaling linking RNA degradation/decapping and regulation of translation.
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Affiliation(s)
- Jonathan D Dougherty
- From the Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas 77030
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15
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Intracellular ribonucleases involved in transcript processing and decay: precision tools for RNA. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2013; 1829:491-513. [PMID: 23545199 DOI: 10.1016/j.bbagrm.2013.03.009] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 03/19/2013] [Accepted: 03/22/2013] [Indexed: 12/15/2022]
Abstract
In order to adapt to changing environmental conditions and regulate intracellular events such as division, cells are constantly producing new RNAs while discarding old or defective transcripts. These functions require the coordination of numerous ribonucleases that precisely cleave and trim newly made transcripts to produce functional molecules, and rapidly destroy unnecessary cellular RNAs. In recent years our knowledge of the nature, functions and structures of these enzymes in bacteria, archaea and eukaryotes has dramatically expanded. We present here a synthetic overview of the recent development in this dynamic area which has seen the identification of many new endoribonucleases and exoribonucleases. Moreover, the increasing pace at which the structures of these enzymes, or of their catalytic domains, have been solved has provided atomic level detail into their mechanisms of action. Based on sequence conservation and structural data, these proteins have been grouped into families, some of which contain only ribonuclease members, others including a variety of nucleolytic enzymes that act upon DNA and/or RNA. At the other extreme some ribonucleases belong to families of proteins involved in a wide variety of enzymatic reactions. Functional characterization of these fascinating enzymes has provided evidence for the extreme diversity of their biological functions that include, for example, removal of poly(A) tails (deadenylation) or poly(U) tails from eukaryotic RNAs, processing of tRNA and mRNA 3' ends, maturation of rRNAs and destruction of unnecessary mRNAs. This article is part of a Special Issue entitled: RNA Decay mechanisms.
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Abstract
The degradation of RNA is a critical aspect of gene regulation. Correspondingly, ribonucleases exist within the cell to degrade RNA in specific cellular contexts. An important and conserved ribonuclease is called XRN1. This enzyme, an exoribonuclease, degrades RNA in a processive 5' to 3' direction. Substrates for XRN1 include decapped mRNA, endonucleolytically cleaved mRNA, lncRNA, and some aberrant tRNAs. In addition, XRN1 serves a vital role in the processing and maturation of the 5' ends of rRNA and snoRNAs. In this review, we discuss some of the important roles of XRN1 in the cell.
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17
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Abstract
All RNA species in yeast cells are subject to turnover. Work over the past 20 years has defined degradation mechanisms for messenger RNAs, transfer RNAs, ribosomal RNAs, and noncoding RNAs. In addition, numerous quality control mechanisms that target aberrant RNAs have been identified. Generally, each decay mechanism contains factors that funnel RNA substrates to abundant exo- and/or endonucleases. Key issues for future work include determining the mechanisms that control the specificity of RNA degradation and how RNA degradation processes interact with translation, RNA transport, and other cellular processes.
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Affiliation(s)
- Roy Parker
- Department of Molecular and Cellular Biology, University of Arizona and Howard Hughes Medical Institute, Tucson, AZ 85721, USA.
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18
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Sharwood RE, Halpert M, Luro S, Schuster G, Stern DB. Chloroplast RNase J compensates for inefficient transcription termination by removal of antisense RNA. RNA (NEW YORK, N.Y.) 2011; 17:2165-76. [PMID: 22033332 PMCID: PMC3222129 DOI: 10.1261/rna.028043.111] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Accepted: 09/13/2011] [Indexed: 05/20/2023]
Abstract
Ribonuclease J is an essential enzyme, and the Bacillus subtilis ortholog possesses both endoribonuclease and 5' → 3' exoribonuclease activities. Chloroplasts also contain RNase J, which has been postulated to participate, as both an exo- and endonuclease, in the maturation of polycistronic mRNAs. Here we have examined recombinant Arabidopsis RNase J and found both 5' → 3' exoribonuclease and endonucleolytic activities. Virus-induced gene silencing was used to reduce RNase J expression in Arabidopsis and Nicotiana benthamiana, leading to chlorosis but surprisingly few disruptions in the cleavage of polycistronic rRNA and mRNA precursors. In contrast, antisense RNAs accumulated massively, suggesting that the failure of chloroplast RNA polymerase to terminate effectively leads to extensive symmetric transcription products that are normally eliminated by RNase J. Mung bean nuclease digestion and polysome analysis revealed that this antisense RNA forms duplexes with sense strand transcripts and prevents their translation. We conclude that a major role of chloroplast RNase J is RNA surveillance to prevent overaccumulation of antisense RNA, which would otherwise exert deleterious effects on chloroplast gene expression.
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Affiliation(s)
- Robert E. Sharwood
- Boyce Thompson Institute for Plant Research, Ithaca, New York 14853, USA
| | - Michal Halpert
- Department of Biology, Technion–Israel Institute of Technology, Haifa 32000, Israel
| | - Scott Luro
- Boyce Thompson Institute for Plant Research, Ithaca, New York 14853, USA
| | - Gadi Schuster
- Department of Biology, Technion–Israel Institute of Technology, Haifa 32000, Israel
| | - David B. Stern
- Boyce Thompson Institute for Plant Research, Ithaca, New York 14853, USA
- Corresponding author.E-mail .
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19
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Ramírez-Garrastacho M, Esteban R. Yeast RNA viruses as indicators of exosome activity: human exosome hCsl4p participates in RNA degradation in Saccharomyces cerevisiae'. Yeast 2011; 28:821-32. [PMID: 22068837 DOI: 10.1002/yea.1909] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Accepted: 09/26/2011] [Indexed: 11/07/2022] Open
Abstract
The exosome is an evolutionarily conserved 10-mer complex involved in RNA metabolism, located in both the nucleus and the cytoplasm. The cytoplasmic exosome plays an important role in mRNA turnover through its 3'→5' exonucleolytic activity. The superkiller (SKI) phenotype of yeast was originally identified as an increase of killer toxin production due to elevated levels of the L-A double-stranded RNA (dsRNA) Totivirus and its satellite toxin-encoding M dsRNA. Most SKI genes were later shown to be either components of the exosome or modulators of its activity. Variations in the amount of Totivirus are, thus, good indicators of yeast exosome activity, and can be used to analyse its components. Furthermore, if exosome proteins of higher eukaryotes were functional in S. cerevisiae, these viruses would provide a simple tool to analyse their function. In this work, we have found that hCSL4, the human orthologue of SKI4 in the yeast exosome, rescues the null phenotype of the deletion mutant. hCsl4p shares with Ski4p conserved S1 RNA-binding domains, but lacks the N-terminal third of Ski4p. Nevertheless, it interacts with the Dis3p exonuclease of yeast exosome, and partially complements the superkiller phenotype of ski4-1 mutation. The elimination of the N-terminal third of Ski4p does not affect its activity, indicating that it is dispensable for RNA degradation. We have also identified the point mutation G152E in hCSL4, equivalent to the ski4-1 mutation G253E, which impairs the activity of the protein, thus validating our approach of using yeast RNA virus to analyse the exosome of higher eukaryotes.
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Affiliation(s)
- Manuel Ramírez-Garrastacho
- Instituto de Biología Funcional y Genómica, Consejo Superior de Investigaciones Científicas, Universidad de Salamanca, Spain
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20
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Zinc-finger antiviral protein inhibits HIV-1 infection by selectively targeting multiply spliced viral mRNAs for degradation. Proc Natl Acad Sci U S A 2011; 108:15834-9. [PMID: 21876179 DOI: 10.1073/pnas.1101676108] [Citation(s) in RCA: 208] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The zinc-finger antiviral protein (ZAP) was originally identified as a host factor that inhibits the replication of Moloney murine leukemia virus. Here we report that ZAP inhibits HIV-1 infection by promoting the degradation of specific viral mRNAs. Overexpression of ZAP rendered cells resistant to HIV-1 infection in a ZAP expression level-dependent manner, whereas depletion of endogenous ZAP enhanced HIV-1 infection. Both human and rat ZAP inhibited the propagation of replication-competent HIV-1. ZAP specifically targeted the multiply spliced but not unspliced or singly spliced HIV-1 mRNAs for degradation. We provide evidence indicating that ZAP selectively recruits cellular poly(A)-specific ribonuclease (PARN) to shorten the poly(A) tail of target viral mRNA and recruits the RNA exosome to degrade the RNA body from the 3' end. In addition, ZAP recruits cellular decapping complex through its cofactor RNA helicase p72 to initiate degradation of the target viral mRNA from the 5' end. Depletion of each of these mRNA degradation enzymes reduced ZAP's activity. Our results indicate that ZAP inhibits HIV-1 by recruiting both the 5' and 3' mRNA degradation machinery to specifically promote the degradation of multiply spliced HIV-1 mRNAs.
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21
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Jinek M, Coyle SM, Doudna JA. Coupled 5' nucleotide recognition and processivity in Xrn1-mediated mRNA decay. Mol Cell 2011; 41:600-8. [PMID: 21362555 DOI: 10.1016/j.molcel.2011.02.004] [Citation(s) in RCA: 135] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Revised: 12/13/2010] [Accepted: 12/23/2010] [Indexed: 10/18/2022]
Abstract
Messenger RNA decay plays a central role in the regulation and surveillance of eukaryotic gene expression. The conserved multidomain exoribonuclease Xrn1 targets cytoplasmic RNA substrates marked by a 5' monophosphate for processive 5'-to-3' degradation by an unknown mechanism. Here, we report the crystal structure of an Xrn1-substrate complex. The single-stranded substrate is held in place by stacking of the 5'-terminal trinucleotide between aromatic side chains while a highly basic pocket specifically recognizes the 5' phosphate. Mutations of residues involved in binding the 5'-terminal nucleotide impair Xrn1 processivity. The substrate recognition mechanism allows Xrn1 to couple processive hydrolysis to duplex melting in RNA substrates with sufficiently long single-stranded 5' overhangs. The Xrn1-substrate complex structure thus rationalizes the exclusive specificity of Xrn1 for 5'-monophosphorylated substrates, ensuring fidelity of mRNA turnover, and posits a model for translocation-coupled unwinding of structured RNA substrates.
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Affiliation(s)
- Martin Jinek
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
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22
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Fujimura T, Esteban R. Yeast double-stranded RNA virus L-A deliberately synthesizes RNA transcripts with 5'-diphosphate. J Biol Chem 2010; 285:22911-8. [PMID: 20511225 DOI: 10.1074/jbc.m110.138982] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
L-A is a persistent double-stranded RNA virus commonly found in the yeast Saccharomyces cerevisiae. Isolated L-A virus synthesizes positive strand transcripts in vitro. We found that the 5' termini of the transcripts are diphosphorylated. The 5'-terminal nucleotide is G, and GDP was the best substrate among those examined to prime the reaction. When GTP was used, the triphosphate of GTP incorporated into the 5'-end was converted to diphosphate. This activity was not dependent on host CTL1 RNA triphosphatase. The 5'-end of the GMP-primed transcript also was converted to diphosphate, the beta-phosphate of which was derived from the gamma-phosphate of ATP present in the polymerization reaction. These results demonstrate that L-A virus commands elaborate enzymatic systems to ensure its transcript to be 5'-diphosphorylated. Transcripts of M1, a satellite RNA of L-A virus, also had diphosphate at the 5' termini. Because viral transcripts are released from the virion into the cytoplasm to be translated and encapsidated into a new viral particle, a stage most vulnerable to degradation in the virus replication cycle, our results suggest that the 5'-diphosphate status is important for transcript stability. Consistent with this, L-A transcripts made in vitro are resistant to the affinity-purified Ski1p 5'-exonuclease. We also discuss the implication of these findings on translation of viral RNA. Because the viral transcript has no conventional 5'-cap structure, this work may shed light on the metabolism of non-self-RNA in yeast.
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Affiliation(s)
- Tsutomu Fujimura
- Instituto de Microbiología Bioquímica/Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas/Universidad de Salamanca, Salamanca 37007, Spain.
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23
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Hu W, Sweet TJ, Chamnongpol S, Baker KE, Coller J. Co-translational mRNA decay in Saccharomyces cerevisiae. Nature 2009; 461:225-9. [PMID: 19701183 PMCID: PMC2745705 DOI: 10.1038/nature08265] [Citation(s) in RCA: 238] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2009] [Accepted: 07/06/2009] [Indexed: 11/26/2022]
Abstract
The rates of RNA decay and transcription determine the steady state levels of all mRNAs and both can be subject to regulation. While the details of transcriptional regulation are becoming increasingly understood, the mechanism(s) controlling mRNA decay remain unclear. In yeast, a major pathway of mRNA decay begins with deadenylation followed by decapping and 5’-3’ exonuclease digestion. Importantly, it is hypothesized that ribosomes must be removed from mRNA before transcripts are destroyed. Contrary to this prediction, here we show that decay takes place while mRNAs are associated with actively translating ribosomes. The data indicate that dissociation of ribosomes from mRNA is not a prerequisite for decay and we suggest that the 5’-3’ polarity of mRNA degradation has evolved to ensure that the last translocating ribosome can complete translation.
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Affiliation(s)
- Wenqian Hu
- Center for RNA Molecular Biology, Case Western Reserve University, Cleveland, Ohio 44106, USA
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24
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Jain R, Shuman S. Characterization of a thermostable archaeal polynucleotide kinase homologous to human Clp1. RNA (NEW YORK, N.Y.) 2009; 15:923-31. [PMID: 19299550 PMCID: PMC2673061 DOI: 10.1261/rna.1492809] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2008] [Accepted: 01/21/2009] [Indexed: 05/24/2023]
Abstract
Clp1 proteins are essential components of the eukaryal mRNA 3' cleavage-polyadenylation machinery. Human Clp1 has an additional function as an RNA-specific 5'-OH polynucleotide kinase, which is implicated in RNA end healing. Yeast Clp1 has no kinase activity, although it binds ATP. Here we report that Clp1-like proteins are extant in archaea. Purification and characterization of Pyrococcus horikoshii Clp1 (PhoClp1) reveals it to be a thermostable 5'-OH polynucleotide kinase optimally active at 55 degrees C to 85 degrees C. PhoClp1 catalyzes transfer of the gamma phosphate from ATP (K (m) 16 microM) to either 5'-OH RNA or DNA ends, although it prefers RNA in a competitive situation. Increasing the monovalent salt concentration to 250 mM suppresses the DNA kinase without affecting RNA phosphorylation, suggesting that RNA is a likely substrate for this enzyme in vivo. Indeed, we show that expression of PhoClp1 in budding yeast can complement a lethal mutation in the 5'-OH RNA kinase module of tRNA ligase. PhoClp1 is a member of the P-loop phosphotransferase superfamily. Alanine mutations at the P-loop lysine (Lys49) and a conserved aspartate (Asp73) inactivate the kinase. Our studies fortify emerging evidence for an enzymatic RNA repair capacity in archaea and provide a new reagent for polynucleotide phosphorylation at high temperatures.
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Affiliation(s)
- Ruchi Jain
- Graduate Program in Chemical Biology, Sloan-Kettering Institute, New York, New York 10065, USA
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25
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Pijlman GP, Funk A, Kondratieva N, Leung J, Torres S, van der Aa L, Liu WJ, Palmenberg AC, Shi PY, Hall RA, Khromykh AA. A highly structured, nuclease-resistant, noncoding RNA produced by flaviviruses is required for pathogenicity. Cell Host Microbe 2009; 4:579-91. [PMID: 19064258 DOI: 10.1016/j.chom.2008.10.007] [Citation(s) in RCA: 361] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2008] [Revised: 06/10/2008] [Accepted: 10/15/2008] [Indexed: 01/01/2023]
Abstract
Viral noncoding RNAs have been shown to play an important role in virus-host interplay to facilitate virus replication. We report that members of the genus Flavivirus, a large group of medically important encephalitic RNA viruses, produce a unique and highly structured noncoding RNA of 0.3-0.5 kb derived from the 3' untranslated region of the viral genome. Using West Nile virus as a model, we show that this subgenomic RNA is a product of incomplete degradation of viral genomic RNA by cellular ribonucleases. Highly conserved RNA structures located at the beginning of the 3' untranslated region render this RNA resistant to nucleases, and the resulting subgenomic RNA product is essential for virus-induced cytopathicity and pathogenicity. Thus, flaviviruses evolved a unique strategy to generate a noncoding RNA product that allows them to kill the host more efficiently.
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Affiliation(s)
- Gorben P Pijlman
- School of Molecular and Microbial Sciences, The University of Queensland, Brisbane, Queensland, Australia
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26
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Esteban R, Vega L, Fujimura T. 20S RNA narnavirus defies the antiviral activity of SKI1/XRN1 in Saccharomyces cerevisiae. J Biol Chem 2008; 283:25812-20. [PMID: 18640978 DOI: 10.1074/jbc.m804400200] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
20S RNA virus is a persistent positive strand RNA virus found in Saccharomyces cerevisiae. We previously observed that the virus generated in vivo from a launching vector possessed the correct RNA termini without extra sequences. Here we present evidence that the SKI1/XRN1 5'-exonuclease plays a major role in the elimination of the non-viral upstream sequences from the primary transcripts. The virus, once generated, however, is fairly unaffected by overexpression or deletion of SKI1/XRN1. By contrast, the copy number of the L-A double-stranded RNA virus in the same host is greatly increased by the deletion of SKI1/XRN1, and overexpression of the gene cured L-A virus from the cells at a high frequency. 20S RNA virus, unlike L-A virus, has a strong secondary structure at its 5'-end: the first four nucleotides are G, and they are buried at the bottom of a long stem structure, features known to inhibit the SKI1/XRN1 5'-exonuclease progression. Mutations that weakened the 5'-stem structure made 20S RNA virus vulnerable to SKI1/XRN1. These results, together with the data on L-A virus, indicate a strong anti-RNA virus activity of SKI1/XRN1. Given that 20S RNA virus resides and replicates in the cytoplasm without a protective capsid, our results suggest that the strong secondary structure at the 5'-end is crucial for the 20S RNA virus to evade the host SKI1/XRN1 defense.
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Affiliation(s)
- Rosa Esteban
- Instituto de Microbiología Bioquímica, Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas/Universidad de Salamanca, Salamanca 37007, Spain.
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27
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Pellegrini O, Mathy N, Condon C, Bénard L. Chapter 9 In Vitro Assays of 5′ to 3′‐Exoribonuclease Activity. Methods Enzymol 2008; 448:167-83. [DOI: 10.1016/s0076-6879(08)02609-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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28
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Mathy N, Bénard L, Pellegrini O, Daou R, Wen T, Condon C. 5'-to-3' exoribonuclease activity in bacteria: role of RNase J1 in rRNA maturation and 5' stability of mRNA. Cell 2007; 129:681-92. [PMID: 17512403 DOI: 10.1016/j.cell.2007.02.051] [Citation(s) in RCA: 266] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2006] [Revised: 12/14/2006] [Accepted: 02/26/2007] [Indexed: 10/23/2022]
Abstract
Although the primary mechanism of eukaryotic messenger RNA decay is exoribonucleolytic degradation in the 5'-to-3' orientation, it has been widely accepted that Bacteria can only degrade RNAs with the opposite polarity, i.e. 3' to 5'. Here we show that maturation of the 5' side of Bacillus subtilis 16S ribosomal RNA occurs via a 5'-to-3' exonucleolytic pathway, catalyzed by the widely distributed essential ribonuclease RNase J1. The presence of a 5'-to-3' exoribonuclease activity in B. subtilis suggested an explanation for the phenomenon whereby mRNAs in this organism are stabilized for great distances downstream of "roadblocks" such as stalled ribosomes or stable secondary structures, whereas upstream sequences are never detected. We show that a 30S ribosomal subunit bound to a Shine Dalgarno-like element (Stab-SD) in the cryIIIA mRNA blocks exonucleolytic progression of RNase J1, accounting for the stabilizing effect of this element in vivo.
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Affiliation(s)
- Nathalie Mathy
- CNRS UPR 9073 (affiliated with Université de Paris 7 - Denis Diderot), Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, 75005 Paris
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29
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Fujimura T, Esteban R. Interactions of the RNA polymerase with the viral genome at the 5'- and 3'-ends contribute to 20S RNA narnavirus persistence in yeast. J Biol Chem 2007; 282:19011-9. [PMID: 17478418 DOI: 10.1074/jbc.m702432200] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
20S RNA narnavirus is a positive strand RNA virus found in the yeast Saccharomyces cerevisiae. The viral genome (2514 nucleotides) only encodes a single protein (p91), the RNA-dependent RNA polymerase and does not have capsid proteins to form intracellular virions. The genomic RNA has no 3' poly(A) tail and perhaps no cap structure at the 5'-end; thus resembling an intermediate of mRNA degradation. The virus, however, escapes the host surveillance and replicates in the yeast cytoplasm persistently. The viral genome is not naked but exists in the form of a ribonucleoprotein complex with p91 in a 1:1 stoichiometry. Here we investigated interactions between p91 and the viral genome. Our results indicate that p91 directly or indirectly interacts with the RNA at the 5'- and 3'-end regions and to a lesser extent at a central part. The 3'-end site is identical to or overlaps with the 3' cis signal for replication identified previously. The 5'-site is at the second stem loop structure from the 5'-end (nucleotides 72-104), and this structure also contains a cis signal for replication. Analysis of mutants in the structure revealed a tight correlation between replication and formation of complexes. These results highlight the importance of ribonucleoprotein complexes for the viral life cycle. We will discuss implications of these findings especially on how the virus escapes from mRNA degradation pathways and resides in the cytoplasm persistently despite the lack of a protective capsid.
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Affiliation(s)
- Tsutomu Fujimura
- Instituto de Microbiología Bioquímica/Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas/Universidad de Salamanca, 37007 Salamanca, Spain
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30
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Cheng CP, Serviene E, Nagy PD. Suppression of viral RNA recombination by a host exoribonuclease. J Virol 2006; 80:2631-40. [PMID: 16501073 PMCID: PMC1395426 DOI: 10.1128/jvi.80.6.2631-2640.2006] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2005] [Accepted: 12/17/2005] [Indexed: 11/20/2022] Open
Abstract
RNA viruses of humans, animals, and plants evolve rapidly due to mutations and RNA recombination. A previous genome-wide screen in Saccharomyces cerevisiae, a model host, identified five host genes, including XRN1, encoding a 5'-3' exoribonuclease, whose absence led to an approximately 10- to 50-fold enhancement of RNA recombination in Tomato bushy stunt virus (E. Serviene, N. Shapka, C. P. Cheng, T. Panavas, B. Phuangrat, J. Baker, and P. D. Nagy, Proc. Natl. Acad. Sci. USA 102:10545-10550, 2005). In this study, we found abundant 5'-truncated viral RNAs in xrn1delta mutant strains but not in the parental yeast strains, suggesting that these RNAs might serve as recombination substrates promoting RNA recombination in xrn1delta mutant yeast. This model is supported by data showing that an enhanced level of viral recombinant accumulation occurred when two different 5'-truncated viral RNAs were expressed in the parental and xrn1delta mutant yeast strains or electroporated into plant protoplasts. Moreover, we demonstrate that purified Xrn1p can degrade the 5'-truncated viral RNAs in vitro. Based on these findings, we propose that Xrn1p can suppress viral RNA recombination by rapidly removing the 5'-truncated RNAs, the substrates of recombination, and thus reducing the chance for recombination to occur in the parental yeast strain. In addition, we show that the 5'-truncated viral RNAs are generated by host endoribonucleases. Accordingly, overexpression of the Ngl2p endoribonuclease led to an increased accumulation of cleaved viral RNAs in vivo and in vitro. Altogether, this paper establishes that host ribonucleases and host-mediated viral RNA turnover play major roles in RNA virus recombination and evolution.
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Affiliation(s)
- Chi-Ping Cheng
- Department of Plant Pathology, University of Kentucky, Plant Science Building, Lexington, Kentucky 40546, USA
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Kedersha N, Stoecklin G, Ayodele M, Yacono P, Lykke-Andersen J, Fritzler MJ, Scheuner D, Kaufman RJ, Golan DE, Anderson P. Stress granules and processing bodies are dynamically linked sites of mRNP remodeling. ACTA ACUST UNITED AC 2005; 169:871-84. [PMID: 15967811 PMCID: PMC2171635 DOI: 10.1083/jcb.200502088] [Citation(s) in RCA: 1098] [Impact Index Per Article: 57.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Stress granules (SGs) are cytoplasmic aggregates of stalled translational preinitiation complexes that accumulate during stress. GW bodies/processing bodies (PBs) are distinct cytoplasmic sites of mRNA degradation. In this study, we show that SGs and PBs are spatially, compositionally, and functionally linked. SGs and PBs are induced by stress, but SG assembly requires eIF2alpha phosphorylation, whereas PB assembly does not. They are also dispersed by inhibitors of translational elongation and share several protein components, including Fas-activated serine/threonine phosphoprotein, XRN1, eIF4E, and tristetraprolin (TTP). In contrast, eIF3, G3BP, eIF4G, and PABP-1 are restricted to SGs, whereas DCP1a and 2 are confined to PBs. SGs and PBs also can harbor the same species of mRNA and physically associate with one another in vivo, an interaction that is promoted by the related mRNA decay factors TTP and BRF1. We propose that mRNA released from disassembled polysomes is sorted and remodeled at SGs, from which selected transcripts are delivered to PBs for degradation.
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Affiliation(s)
- Nancy Kedersha
- Division of Rheumatology and Immunology, Harvard Medical School, Brigham and Women's Hospital, Boston, MA 02115, USA.
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Orban TI, Izaurralde E. Decay of mRNAs targeted by RISC requires XRN1, the Ski complex, and the exosome. RNA (NEW YORK, N.Y.) 2005; 11:459-69. [PMID: 15703439 PMCID: PMC1370735 DOI: 10.1261/rna.7231505] [Citation(s) in RCA: 223] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2004] [Accepted: 12/20/2004] [Indexed: 05/21/2023]
Abstract
RNA interference (RNAi) is a conserved RNA silencing pathway that leads to sequence-specific mRNA decay in response to the presence of double-stranded RNA (dsRNA). Long dsRNA molecules are first processed by Dicer into 21-22-nucleotide small interfering RNAs (siRNAs). The siRNAs are incorporated into a multimeric RNA-induced silencing complex (RISC) that cleaves mRNAs at a site determined by complementarity with the siRNAs. Following this initial endonucleolytic cleavage, the mRNA is degraded by a mechanism that is not completely understood. We investigated the decay pathway of mRNAs targeted by RISC in Drosophila cells. We show that 5' mRNA fragments generated by RISC cleavage are rapidly degraded from their 3' ends by the exosome, whereas the 3' fragments are degraded from their 5' ends by XRN1. Exosome-mediated decay of the 5' fragments requires the Drosophila homologs of yeast Ski2p, Ski3p, and Ski8p, suggesting that their role as regulators of exosome activity is conserved. Our findings indicate that mRNAs targeted by siRNAs are degraded from the ends generated by RISC cleavage, without undergoing decapping or deadenylation.
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Gazzani S, Lawrenson T, Woodward C, Headon D, Sablowski R. A link between mRNA turnover and RNA interference in Arabidopsis. Science 2004; 306:1046-8. [PMID: 15528448 DOI: 10.1126/science.1101092] [Citation(s) in RCA: 224] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
In RNA interference (RNAi), double-stranded RNA (dsRNA) triggers degradation of homologous messenger RNA. In many organisms, RNA-dependent RNA polymerase (RdRp) is required to initiate or amplify RNAi, but the substrate for dsRNA synthesis in vivo is not known. Here, we show that RdRp-dependent transgene silencing in Arabidopsis was caused by mutation of XRN4, which is a ribonuclease (RNase) implicated in mRNA turnover by means of decapping and 5'-3' exonucleolysis. When both XRN4 and the RdRp were mutated, the plants accumulated decapped transgene mRNA. We propose that mRNAs lacking a cap structure become exposed to RdRp to initiate or maintain RNAi.
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Affiliation(s)
- S Gazzani
- Cell and Developmental Biology, John Innes Centre, Norwich NR4 7UH, UK
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