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Li Y, Zhang L, Wang L, Li J, Zhao Y, Liu F, Wang Q. Structure and function of type IV IRES in picornaviruses: a systematic review. Front Microbiol 2024; 15:1415698. [PMID: 38855772 PMCID: PMC11157119 DOI: 10.3389/fmicb.2024.1415698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2024] [Accepted: 05/13/2024] [Indexed: 06/11/2024] Open
Abstract
The Picornaviridae is a family of icosahedral viruses with single-stranded, highly diverse positive-sense RNA genomes. Virions consist of a capsid, without envelope, surrounding a core of RNA genome. A typical genome of picornavirus harbors a well-conserved and highly structured RNA element known as the internal ribosome entry site (IRES), functionally essential for viral replication and protein translation. Based on differences in their structures and mechanisms of action, picornaviral IRESs have been categorized into five types: type I, II, III, IV, and V. Compared with the type IV IRES, the others not only are structurally complicated, but also involve multiple initiation factors for triggering protein translation. The type IV IRES, often referred to as hepatitis C virus (HCV)-like IRES due to its structural resemblance to the HCV IRES, exhibits a simpler and more compact structure than those of the other four. The increasing identification of picornaviruses with the type IV IRES suggests that this IRES type seems to reveal strong retention and adaptation in terms of viral evolution. Here, we systematically reviewed structural features and biological functions of the type IV IRES in picornaviruses. A comprehensive understanding of the roles of type IV IRESs will contribute to elucidating the replication mechanism and pathogenesis of picornaviruses.
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Affiliation(s)
- Yan Li
- College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, China
- Qingdao Center for Animal Disease Control and Prevention, Qingdao, China
| | - Lei Zhang
- Shandong New Hope Liuhe Group Co., Ltd., Qingdao, China
| | - Ling Wang
- University Hospital, Qingdao Agricultural University, Qingdao, China
| | - Jing Li
- Market Supervision Administration of Huangdao District, Qingdao, China
| | - Yanwei Zhao
- College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, China
| | - Fuxiao Liu
- College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, China
| | - Qianqian Wang
- College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, China
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2
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Ning H, Liu G, Li L, Liu Q, Huang H, Xie Z. Rational design of microRNA-responsive switch for programmable translational control in mammalian cells. Nat Commun 2023; 14:7193. [PMID: 37938567 PMCID: PMC10632459 DOI: 10.1038/s41467-023-43065-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 10/30/2023] [Indexed: 11/09/2023] Open
Abstract
Artificial RNA translation modulation usually relies on multiple components, such as RNA binding proteins (RBPs) or microRNAs (miRNAs) for off-switches and double-inverter cascades for on-switches. Recently, translational circular RNAs (circRNAs) were developed as promising alternatives for linear messenger RNAs (mRNAs). However, circRNAs still lack straightforward and programmable translation control strategies. Here, we rationally design a programmable miRNA-responsive internal ribosome entry site (IRES) translation activation and repression (PROMITAR) platform capable of implementing miRNA-based translation upregulation and downregulation in a single RNA construct. Based on the PROMITAR platform, we construct logic gates and cell-type classifier circRNAs and successfully identify desired mammalian cell types. We also demonstrate the potential therapeutic application of our platform for targeted cancer cell killing by encoding a cytotoxic protein in our engineered circRNAs. We expect our platform to expand the toolbox for RNA synthetic biology and provide an approach for potential biomedical applications in the future.
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Affiliation(s)
- Hui Ning
- MOE Key Laboratory of Bioinformatics and Bioinformatics Division, Center for Synthetic and Systems Biology, Department of Automation, Beijing National Research Center for Information Science and Technology, Tsinghua University, Beijing, 100084, China
| | - Gan Liu
- Syngentech Inc., Zhongguancun Life Science Park, Changping District, Beijing, 102206, China
| | - Lei Li
- MOE Key Laboratory of Bioinformatics and Bioinformatics Division, Center for Synthetic and Systems Biology, Department of Automation, Beijing National Research Center for Information Science and Technology, Tsinghua University, Beijing, 100084, China
| | - Qiang Liu
- Syngentech Inc., Zhongguancun Life Science Park, Changping District, Beijing, 102206, China
| | - Huiya Huang
- Syngentech Inc., Zhongguancun Life Science Park, Changping District, Beijing, 102206, China
| | - Zhen Xie
- MOE Key Laboratory of Bioinformatics and Bioinformatics Division, Center for Synthetic and Systems Biology, Department of Automation, Beijing National Research Center for Information Science and Technology, Tsinghua University, Beijing, 100084, China.
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3
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Wang Q, Zhao D, Wang L, Sang Y, Meng H, Wang Q, Shan H, Liu F, Geri L. Translation of Senecavirus A polyprotein is initiated from the IRES-proximal initiation codon. Virology 2023; 579:67-74. [PMID: 36608596 DOI: 10.1016/j.virol.2022.12.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 12/19/2022] [Accepted: 12/19/2022] [Indexed: 12/31/2022]
Abstract
To clarify whether Senecavirus A (SVA) has the potential of alternative translation, an extra G residue was inserted into an SVA cDNA clone, resultantly generating an "AUGAUG" motif. The second AUG is the authentic SVA initiation codon, whereas the first AUG is a putative one. Subsequently, eighteen nucleotides were inserted one by one between AUG and AUG for reconstructing cDNA clones. The test of virus recovery showed that three replication-competent SVAs, whose AUG/AUG-flanked sequences were not multiples of three nucleotides, were successfully rescued from their individual cDNA clones. The wild-type SVA possesses a UUUUU motif within the polyprotein-encoding region. Sanger sequencing showed that these three replication-competent SVAs harbored one or two extra U residues in the UUUUU motif, implying that polyprotein translation was initiated from the putative AUG, and the authentic AUG would be inactivated. This is probably attributed to the lack of ribosome scanning along an SVA genome.
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Affiliation(s)
- Qianqian Wang
- College of Veterinary Medicine, Inner Mongolia Agricultural University, Hohhot, 010011, China
| | - Di Zhao
- College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, 266109, China
| | - Ling Wang
- University Hospital, Qingdao Agricultural University, Qingdao, 266109, China
| | - Yuxuan Sang
- College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, 266109, China
| | - Hailan Meng
- College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, 266109, China
| | - Qi Wang
- College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, 266109, China
| | - Hu Shan
- College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, 266109, China
| | - Fuxiao Liu
- College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, 266109, China.
| | - Letu Geri
- College of Veterinary Medicine, Inner Mongolia Agricultural University, Hohhot, 010011, China.
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4
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Wan H, Adams RL, Lindenbach BD, Pyle AM. The In Vivo and In Vitro Architecture of the Hepatitis C Virus RNA Genome Uncovers Functional RNA Secondary and Tertiary Structures. J Virol 2022; 96:e0194621. [PMID: 35353000 PMCID: PMC9044954 DOI: 10.1128/jvi.01946-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 02/24/2022] [Indexed: 01/21/2023] Open
Abstract
Hepatitis C virus (HCV) is a positive-strand RNA virus that remains one of the main contributors to chronic liver disease worldwide. Studies over the last 30 years have demonstrated that HCV contains a highly structured RNA genome and many of these structures play essential roles in the HCV life cycle. Despite the importance of riboregulation in this virus, most of the HCV RNA genome remains functionally unstudied. Here, we report a complete secondary structure map of the HCV RNA genome in vivo, which was studied in parallel with the secondary structure of the same RNA obtained in vitro. Our results show that HCV is folded extensively in the cellular context. By performing comprehensive structural analyses on both in vivo data and in vitro data, we identify compact and conserved secondary and tertiary structures throughout the genome. Genetic and evolutionary functional analyses demonstrate that many of these elements play important roles in the virus life cycle. In addition to providing a comprehensive map of RNA structures and riboregulatory elements in HCV, this work provides a resource for future studies aimed at identifying therapeutic targets and conducting further mechanistic studies on this important human pathogen. IMPORTANCE HCV has one of the most highly structured RNA genomes studied to date, and it is a valuable model system for studying the role of RNA structure in protein-coding genes. While previous studies have identified individual cases of regulatory RNA structures within the HCV genome, the full-length structure of the HCV genome has not been determined in vivo. Here, we present the complete secondary structure map of HCV determined both in cells and from corresponding transcripts generated in vitro. In addition to providing a comprehensive atlas of functional secondary structural elements throughout the genomic RNA, we identified a novel set of tertiary interactions and demonstrated their functional importance. In terms of broader implications, the pipeline developed in this study can be applied to other long RNAs, such as long noncoding RNAs. In addition, the RNA structural motifs characterized in this study broaden the repertoire of known riboregulatory elements.
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Affiliation(s)
- Han Wan
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut, USA
| | - Rebecca L. Adams
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut, USA
- Howard Hughes Medical Institute, Chevy Chase, Maryland, USA
| | - Brett D. Lindenbach
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Anna Marie Pyle
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut, USA
- Department of Chemistry, Yale University, New Haven, Connecticut, USA
- Howard Hughes Medical Institute, Chevy Chase, Maryland, USA
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5
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Gosavi D, Wower I, Beckmann IK, Hofacker IL, Wower J, Wolfinger MT, Sztuba-Solinska J. Insights into the secondary and tertiary structure of the Bovine Viral Diarrhea Virus Internal Ribosome Entry Site. RNA Biol 2022; 19:496-506. [PMID: 35380920 PMCID: PMC8986297 DOI: 10.1080/15476286.2022.2058818] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
The internal ribosome entry site (IRES) RNA of bovine viral diarrhoea virus (BVDV), an economically significant Pestivirus, is required for the cap-independent translation of viral genomic RNA. Thus, it is essential for viral replication and pathogenesis. We applied a combination of high-throughput biochemical RNA structure probing (SHAPE-MaP) and in silico modelling approaches to gain insight into the secondary and tertiary structures of BVDV IRES RNA. Our study demonstrated that BVDV IRES RNA in solution forms a modular architecture composed of three distinct structural domains (I-III). Two regions within domain III are represented in tertiary interactions to form an H-type pseudoknot. Computational modelling of the pseudoknot motif provided a fine-grained picture of the tertiary structure and local arrangement of helices in the BVDV IRES. Furthermore, comparative genomics and consensus structure predictions revealed that the pseudoknot is evolutionarily conserved among many Pestivirus species. These studies provide detailed insight into the structural arrangement of BVDV IRES RNA H-type pseudoknot and encompassing motifs that likely contribute to the optimal functionality of viral cap-independent translation element.
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Affiliation(s)
- Devadatta Gosavi
- Department of Biological Sciences, Auburn University, 120 W. Samford Ave, Rouse Life Sciences Building, Auburn, AL, United States
| | - Iwona Wower
- Department of Animal and Dairy Sciences, Auburn University, Auburn, AL, United States
| | - Irene K Beckmann
- Department of Theoretical Chemistry, University of Vienna, Vienna, Austria
| | - Ivo L Hofacker
- Department of Theoretical Chemistry, University of Vienna, Vienna, Austria.,Research Group Bioinformatics and Computational Biology, Faculty of Computer Science, University of Vienna, Vienna, Austria
| | - Jacek Wower
- Department of Animal and Dairy Sciences, Auburn University, Auburn, AL, United States
| | - Michael T Wolfinger
- Department of Theoretical Chemistry, University of Vienna, Vienna, Austria.,Research Group Bioinformatics and Computational Biology, Faculty of Computer Science, University of Vienna, Vienna, Austria
| | - Joanna Sztuba-Solinska
- Department of Biological Sciences, Auburn University, 120 W. Samford Ave, Rouse Life Sciences Building, Auburn, AL, United States.,Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznan, Poland
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6
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Wang N, Wang H, Shi J, Li C, Liu X, Fan J, Sun C, Cameron CE, Qi H, Yu L. The Stem-Loop I of Senecavirus A IRES Is Essential for Cap-Independent Translation Activity and Virus Recovery. Viruses 2021; 13:v13112159. [PMID: 34834966 PMCID: PMC8619302 DOI: 10.3390/v13112159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Revised: 10/07/2021] [Accepted: 10/22/2021] [Indexed: 11/29/2022] Open
Abstract
Senecavirus A (SVA) is a picornavirus that causes vesicular disease in swine and the only member of the Senecavirus genus. Like in all members of Picornaviridae, the 5′ untranslated region (5’UTR) of SVA contains an internal ribosome entry site (IRES) that initiates cap-independent translation. For example, the replacement of the IRES of foot-and-mouth disease virus (FMDV) with its relative bovine rhinitis B virus (BRBV) affects the viral translation efficiency and virulence. Structurally, the IRES from SVA resembles that of hepatitis C virus (HCV), a flavivirus. Given the roles of the IRES in cap-independent translation for picornaviruses, we sought to functionally characterize the IRES of this genus by studying chimeric viruses generated by exchanging the native SVA IRES with that of HCV either entirely or individual domains. First, the results showed that a chimeric SVA virus harboring the IRES from HCV, H-SVA, is viable and replicated normally in rodent-derived BHK-21 cells but displays replication defects in porcine-derived ST cells. In the generation of chimeric viruses in which domain-specific elements from SVA were replaced with those of HCV, we identified an essential role for the stem-loop I element for IRES activity and recombinant virus recovery. Furthermore, a series of stem-loop I mutants allowed us to functionally characterize discrete IRES regions and correlate impaired IRES activities, using reporter systems with our inability to recover recombinant viruses in two different cell types. Interestingly, mutant viruses harboring partially defective IRES were viable. However, no discernable replication differences were observed, relative to the wild-type virus, suggesting the cooperation of additional factors, such as intermolecular viral RNA interactions, act in concert in regulating IRES-dependent translation during infection. Altogether, we found that the stem-loop I of SVA is an essential element for IRES-dependent translation activity and viral replication.
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Affiliation(s)
- Nana Wang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China; (N.W.); (H.W.); (J.S.); (C.L.); (J.F.); (C.S.)
| | - Haiwei Wang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China; (N.W.); (H.W.); (J.S.); (C.L.); (J.F.); (C.S.)
| | - Jiabao Shi
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China; (N.W.); (H.W.); (J.S.); (C.L.); (J.F.); (C.S.)
| | - Chen Li
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China; (N.W.); (H.W.); (J.S.); (C.L.); (J.F.); (C.S.)
| | - Xinran Liu
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA;
| | - Junhao Fan
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China; (N.W.); (H.W.); (J.S.); (C.L.); (J.F.); (C.S.)
| | - Chao Sun
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China; (N.W.); (H.W.); (J.S.); (C.L.); (J.F.); (C.S.)
| | - Craig E. Cameron
- Department of Microbiology and Immunology, University of North Carolina School of Medicine, Chapel Hill, NC 27516, USA;
| | - Hong Qi
- Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, School of Environment, Harbin 150090, China
- Correspondence: (H.Q.); (L.Y.); Tel.: +86-451-51051738 (L.Y.)
| | - Li Yu
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China; (N.W.); (H.W.); (J.S.); (C.L.); (J.F.); (C.S.)
- Correspondence: (H.Q.); (L.Y.); Tel.: +86-451-51051738 (L.Y.)
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7
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Impacts of single nucleotide deletions from the 3' end of Senecavirus A 5' untranslated region on activity of viral IRES and on rescue of recombinant virus. Virology 2021; 563:126-133. [PMID: 34530232 DOI: 10.1016/j.virol.2021.09.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 08/22/2021] [Accepted: 09/05/2021] [Indexed: 02/07/2023]
Abstract
The 5' untranslated region (UTR) of Senecavirus A (SVA) harbors an internal ribosome entry site (IRES), in which a pseudoknot structure is upstream of start codon AUG. Wild-type SVAs have a highly conserved 13-nt-sequence between the pseudoknot stem II (PKS-II)-forming motif and the AUG. In this study, a single nucleotide was deleted one by one from the 13-nt-sequence within a wild-type SVA minigenome. The result showed that neither mono- nor multi-nucleotide deletions abolished the IRES activity. Furthermore, a single nucleotide was deleted one by one from the 13-nt-sequence within a full-length SVA cDNA clone. The result indicated that nucleotide-deleting SVAs could be rescued from 1- to 5-nt-deleting cDNA clones, whereas only the 1- and 2-nt-deleting viruses were genetically stable during nine serial passages in vitro. Additionally, only the 1-nt-deleting SVA showed similar growth kinetics to that of the wild-type virus, suggesting that the pseudoknot-AUG distance was crucial for SVA replication.
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8
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Liu F, Wang N, Huang Y, Wang Q, Shan H. Stem II-disrupting pseudoknot does not abolish ability of Senecavirus A IRES to initiate protein expression, but inhibits recovery of virus from cDNA clone. Vet Microbiol 2021; 255:109024. [PMID: 33713975 DOI: 10.1016/j.vetmic.2021.109024] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 02/26/2021] [Indexed: 12/12/2022]
Abstract
Senecavirus A (SVA) is classified into the genus Senecavirus in the family Picornaviridae. Its genome is a positive-sense, single-stranded and nonsegmented RNA, approximately 7300 nucleotides in length. A picornaviral genome is essentially an mRNA, which, albeit unmodified with 5' cap structure, can still initiate protein expression by the internal ribosome entry site (IRES). The SVA genome contains a hepatitis C virus-like IRES, in which a pseudoknot structure plays an important role in initiating protein expression. In this study, we constructed a set of SVA (CH-LX-01-2016 strain) minigenomes with all combinations of point mutations in its pseudoknot stem II (PKS-II). The results showed that any combination of point mutations could not significantly interfere with the IRES to initiate protein expression. Further, we constructed a full-length SVA cDNA clone, in which the PKS-II-forming cDNA motif was subjected to site-directed mutagenesis for totally disrupting the PKS-II formation in IRES. Such a modified SVA cDNA clone was transfected into BSR-T7/5 cells, consequently demonstrating that the PKS-II-disrupting IRES interfered neither with protein expression nor with antigenome replication, whereas a competent SVA could not be rescued from the cDNA clone. It was speculated that the mutated motif possibly disrupted a packaging signal for virion assembly, therefore causing the failure of SVA rescue.
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Affiliation(s)
- Fuxiao Liu
- College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, 266109, China.
| | - Ning Wang
- College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, 266109, China
| | - Yilan Huang
- College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, 266109, China
| | - Qianqian Wang
- College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, 266109, China
| | - Hu Shan
- College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, 266109, China.
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9
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Hepatitis C Virus Translation Regulation. Int J Mol Sci 2020; 21:ijms21072328. [PMID: 32230899 PMCID: PMC7178104 DOI: 10.3390/ijms21072328] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 03/18/2020] [Accepted: 03/25/2020] [Indexed: 12/12/2022] Open
Abstract
Translation of the hepatitis C virus (HCV) RNA genome is regulated by the internal ribosome entry site (IRES), located in the 5’-untranslated region (5′UTR) and part of the core protein coding sequence, and by the 3′UTR. The 5′UTR has some highly conserved structural regions, while others can assume different conformations. The IRES can bind to the ribosomal 40S subunit with high affinity without any other factors. Nevertheless, IRES activity is modulated by additional cis sequences in the viral genome, including the 3′UTR and the cis-acting replication element (CRE). Canonical translation initiation factors (eIFs) are involved in HCV translation initiation, including eIF3, eIF2, eIF1A, eIF5, and eIF5B. Alternatively, under stress conditions and limited eIF2-Met-tRNAiMet availability, alternative initiation factors such as eIF2D, eIF2A, and eIF5B can substitute for eIF2 to allow HCV translation even when cellular mRNA translation is downregulated. In addition, several IRES trans-acting factors (ITAFs) modulate IRES activity by building large networks of RNA-protein and protein–protein interactions, also connecting 5′- and 3′-ends of the viral RNA. Moreover, some ITAFs can act as RNA chaperones that help to position the viral AUG start codon in the ribosomal 40S subunit entry channel. Finally, the liver-specific microRNA-122 (miR-122) stimulates HCV IRES-dependent translation, most likely by stabilizing a certain structure of the IRES that is required for initiation.
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10
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Romero-López C, Berzal-Herranz A. The Role of the RNA-RNA Interactome in the Hepatitis C Virus Life Cycle. Int J Mol Sci 2020; 21:ijms21041479. [PMID: 32098260 PMCID: PMC7073135 DOI: 10.3390/ijms21041479] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 02/18/2020] [Accepted: 02/19/2020] [Indexed: 02/05/2023] Open
Abstract
RNA virus genomes are multifunctional entities endowed with conserved structural elements that control translation, replication and encapsidation, among other processes. The preservation of these structural RNA elements constraints the genomic sequence variability. The hepatitis C virus (HCV) genome is a positive, single-stranded RNA molecule with numerous conserved structural elements that manage different steps during the infection cycle. Their function is ensured by the association of protein factors, but also by the establishment of complex, active, long-range RNA-RNA interaction networks-the so-called HCV RNA interactome. This review describes the RNA genome functions mediated via RNA-RNA contacts, and revisits some canonical ideas regarding the role of functional high-order structures during the HCV infective cycle. By outlining the roles of long-range RNA-RNA interactions from translation to virion budding, and the functional domains involved, this work provides an overview of the HCV genome as a dynamic device that manages the course of viral infection.
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11
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Lattimer J, Stewart H, Locker N, Tuplin A, Stonehouse NJ, Harris M. Structure-function analysis of the equine hepacivirus 5' untranslated region highlights the conservation of translational mechanisms across the hepaciviruses. J Gen Virol 2019; 100:1501-1514. [PMID: 31490115 PMCID: PMC7615701 DOI: 10.1099/jgv.0.001316] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Equine hepacivirus (EHcV) (now also classified as hepacivirus A) is the closest genetic relative to hepatitis C virus (HCV) and is proposed to have diverged from HCV within the last 1000 years. The 5' untranslated regions (UTRs) of both HCV and EHcV exhibit internal ribosome entry site (IRES) activity, allowing cap-independent translational initiation, yet only the HCV 5'UTR has been systematically analysed. Here, we report a detailed structural and functional analysis of the EHcV 5'UTR. The secondary structure was determined using selective 2' hydroxyl acylation analysed by primer extension (SHAPE), revealing four stem-loops, termed SLI, SLIA, SLII and SLIII, by analogy to HCV. This guided a mutational analysis of the EHcV 5'UTR, allowing us to investigate the roles of the stem-loops in IRES function. This approach revealed that SLI was not required for EHcV IRES-mediated translation. Conversely, SLIII was essential, specifically SLIIIb, SLIIId and a GGG motif that is conserved across the Hepaciviridae. Further SHAPE analysis provided evidence that this GGG motif mediated interaction with the 40S ribosomal subunit, whilst a CUU sequence in the apical loop of SLIIIb mediated an interaction with eIF3. In addition, we showed that a microRNA122 target sequence located between SLIA and SLII mediated an enhancement of translation in the context of a subgenomic replicon. Taken together, these results highlight the conservation of hepaciviral translation mechanisms, despite divergent primary sequences.
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Affiliation(s)
- Joseph Lattimer
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Hazel Stewart
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Nicolas Locker
- Faculty of Health and Medical Sciences, School of Biosciences and Medicine, University of Surrey, Guildford, GU2 7XH, UK
| | - Andrew Tuplin
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Nicola J. Stonehouse
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Mark Harris
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
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12
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Weinberg CE, Weinberg Z, Hammann C. Novel ribozymes: discovery, catalytic mechanisms, and the quest to understand biological function. Nucleic Acids Res 2019; 47:9480-9494. [PMID: 31504786 PMCID: PMC6765202 DOI: 10.1093/nar/gkz737] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Revised: 08/08/2019] [Accepted: 08/21/2019] [Indexed: 12/21/2022] Open
Abstract
Small endonucleolytic ribozymes promote the self-cleavage of their own phosphodiester backbone at a specific linkage. The structures of and the reactions catalysed by members of individual families have been studied in great detail in the past decades. In recent years, bioinformatics studies have uncovered a considerable number of new examples of known catalytic RNA motifs. Importantly, entirely novel ribozyme classes were also discovered, for most of which both structural and biochemical information became rapidly available. However, for the majority of the new ribozymes, which are found in the genomes of a variety of species, a biological function remains elusive. Here, we concentrate on the different approaches to find catalytic RNA motifs in sequence databases. We summarize the emerging principles of RNA catalysis as observed for small endonucleolytic ribozymes. Finally, we address the biological functions of those ribozymes, where relevant information is available and common themes on their cellular activities are emerging. We conclude by speculating on the possibility that the identification and characterization of proteins that we hypothesize to be endogenously associated with catalytic RNA might help in answering the ever-present question of the biological function of the growing number of genomically encoded, small endonucleolytic ribozymes.
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Affiliation(s)
- Christina E Weinberg
- Institute for Biochemistry, Leipzig University, Brüderstraße 34, 04103 Leipzig, Germany
| | - Zasha Weinberg
- Bioinformatics Group, Department of Computer Science and Interdisciplinary Centre for Bioinformatics, Leipzig University, Härtelstraße 16–18, 04107 Leipzig, Germany
| | - Christian Hammann
- Ribogenetics & Biochemistry, Department of Life Sciences and Chemistry, Jacobs University Bremen gGmbH, Campus Ring 1, 28759 Bremen, Germany
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13
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Bernier A, Sagan SM. Beyond sites 1 and 2, miR-122 target sites in the HCV genome have negligible contributions to HCV RNA accumulation in cell culture. J Gen Virol 2019; 100:217-226. [PMID: 30652963 DOI: 10.1099/jgv.0.001217] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Hepatitis C virus (HCV) recruits two molecules of the liver-specific microRNA-122 (miR-122) to two adjacent sites (S1 and S2) located at the 5' end of the viral RNA genome. This interaction promotes HCV RNA accumulation by stabilising the viral RNA and resulting in alteration of the secondary structure of the viral genome. In addition to S1 and S2, the HCV genome contains several other putative miR-122 binding sites, one in the IRES region, three in the NS5B coding region, and one in the 3' UTR. We investigated and compared the relative contributions of the S1, S2, IRES, NS5B (NS5B.1, 2 and 3) and 3' UTR sites on protein expression, viral RNA accumulation, and infectious particle production by mutational analysis and supplementation with compensatory mutant miR-122 molecules. We found that mutations predicted to alter miR-122 binding at the IRES and NS5B.2 sites lead to reductions in HCV core protein expression and viral RNA accumulation; with a concomitant decrease in viral particle production for the NS5B.2 mutant. However, supplementation of miR-122 molecules with compensatory mutations did not rescue these site mutants to wild-type levels, suggesting that mutation of these sequences likely disrupts an additional interaction important to the HCV life cycle, beyond direct interactions with miR-122. Thus, S1 and S2 play a predominant role in viral RNA accumulation, while miR-122 interactions with the IRES, NS5B and 3' UTR regions have negligible contributions to viral protein expression, viral RNA accumulation, and infectious particle production.
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Affiliation(s)
- Annie Bernier
- 1Department of Microbiology and Immunology, McGill University, Montréal, QC, Canada
| | - Selena M Sagan
- 2Department of Biochemistry, McGill University, Montréal, QC, Canada.,1Department of Microbiology and Immunology, McGill University, Montréal, QC, Canada
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14
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Sharma G, Raheja H, Das S. Hepatitis C virus: Enslavement of host factors. IUBMB Life 2018; 70:41-49. [PMID: 29281185 DOI: 10.1002/iub.1702] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 11/20/2017] [Accepted: 11/28/2017] [Indexed: 12/11/2022]
Abstract
Hepatitis C virus (HCV) has infected over 170 million people world-wide. This infection causes severe liver damage that can progress to hepatocellular carcinoma leading to death of the infected patients. Development of a cell culture model system for the study of HCV infection in the recent past has helped the researchers world-wide to understand the biology of this virus. Studies over the past decade have revealed the tricks played by the virus to sustain itself, for as long as 40 years, in the host setup without being eliminated by the immune system. Today we understand that the host organelles and different cellular proteins are affected during HCV infection. This cytoplasmic virus has all the cellular organelles at its disposal to successfully replicate, from ribosomes and intracellular membranous structures to the nucleus. It modulates these organelles at both the structural and the functional levels. The vast knowledge about the viral genome and viral proteins has also helped in the development of drugs against the virus. Despite the achieved success rate to cure the infected patients, we struggle to eliminate the cases of recurrence and the non-responders. Such cases might emerge owing to the property of the viral genome to accumulate mutations during its succeeding replication cycles which favours its survival. The current situation calls an urgent need for alternate therapeutic strategies to counter this major problem of human health. © 2017 IUBMB Life, 70(1):41-49, 2018.
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Affiliation(s)
- Geetika Sharma
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, 560012, Karnataka, India
| | - Harsha Raheja
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, 560012, Karnataka, India
| | - Saumitra Das
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, 560012, Karnataka, India
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15
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Romero-López C, Ríos-Marco P, Berzal-Herranz B, Berzal-Herranz A. The HCV genome domains 5BSL3.1 and 5BSL3.3 act as managers of translation. Sci Rep 2018; 8:16101. [PMID: 30382192 PMCID: PMC6208389 DOI: 10.1038/s41598-018-34422-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 10/12/2018] [Indexed: 02/08/2023] Open
Abstract
The RNA genome of the hepatitis C virus (HCV) encodes a single open reading frame (ORF) containing numerous functional elements. Among these, the cis-acting replication element (CRE) at the 3′ end of the viral ORF, has become of increasing interest given its dual role as a viral translation repressor and replication enhancer. Long-range RNA-RNA contacts mediated by the CRE build the structural scaffold required for its proper functioning. The recruitment of different cellular factors, many related to the functioning of the translation machinery, might aid in the CRE-exerted downregulation of viral translation. The present data show that the CRE promotes a defect in polysome production, and hinders the assembly of the 80S complex, likely through the direct, high affinity recruitment of the 40S ribosomal subunit. This interaction involves the highly conserved 5BSL3.1 and 5BSL3.3 domains of the CRE, and is strictly dependent on RNA-protein contacts, particularly with the ribosomal proteins RPSA and RPS29. These observations support a model in which the CRE-mediated inhibition of viral translation is a multifactorial process defined by the establishment of long-range RNA-RNA interactions between the 5′ and 3′ ends of the viral genome, the sequestration of the 40S subunit by the CRE, and the subsequent stalling of polysome elongation at the 3′ end of the ORF, all governed by the highly stable hairpin domains 5BSL3.1 and 5BSL3.3. The present data thus suggest a new managerial role in HCV translation for these 5BSL3.1 and 5BSL3.3 domains.
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Affiliation(s)
- Cristina Romero-López
- Instituto de Parasitología y Biomedicina López-Neyra, (IPBLN-CSIC), Av. del Conocimiento 17, 18016, Armilla, Granada, Spain.
| | - Pablo Ríos-Marco
- Instituto de Parasitología y Biomedicina López-Neyra, (IPBLN-CSIC), Av. del Conocimiento 17, 18016, Armilla, Granada, Spain
| | - Beatriz Berzal-Herranz
- Instituto de Parasitología y Biomedicina López-Neyra, (IPBLN-CSIC), Av. del Conocimiento 17, 18016, Armilla, Granada, Spain
| | - Alfredo Berzal-Herranz
- Instituto de Parasitología y Biomedicina López-Neyra, (IPBLN-CSIC), Av. del Conocimiento 17, 18016, Armilla, Granada, Spain.
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16
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Kumar R, Khandelwal N, Thachamvally R, Tripathi BN, Barua S, Kashyap SK, Maherchandani S, Kumar N. Role of MAPK/MNK1 signaling in virus replication. Virus Res 2018; 253:48-61. [PMID: 29864503 PMCID: PMC7114592 DOI: 10.1016/j.virusres.2018.05.028] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 04/16/2018] [Accepted: 05/31/2018] [Indexed: 12/23/2022]
Abstract
Viruses are known to exploit cellular signaling pathways. MAPK is a major cell signaling pathway activated by diverse group of viruses. MNK1 regulates both cap-dependent and IRES-mediated mRNA translation. This review discuss the role of MAPK, particularly the role of MNK1 in virus replication.
Viruses are obligate intracellular parasites; they heavily depend on the host cell machinery to effectively replicate and produce new progeny virus particles. Following viral infection, diverse cell signaling pathways are initiated by the cells, with the major goal of establishing an antiviral state. However, viruses have been shown to exploit cellular signaling pathways for their own effective replication. Genome-wide siRNA screens have also identified numerous host factors that either support (proviral) or inhibit (antiviral) virus replication. Some of the host factors might be dispensable for the host but may be critical for virus replication; therefore such cellular factors may serve as targets for development of antiviral therapeutics. Mitogen activated protein kinase (MAPK) is a major cell signaling pathway that is known to be activated by diverse group of viruses. MAPK interacting kinase 1 (MNK1) has been shown to regulate both cap-dependent and internal ribosomal entry sites (IRES)-mediated mRNA translation. In this review we have discuss the role of MAPK in virus replication, particularly the role of MNK1 in replication and translation of viral genome.
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Affiliation(s)
- Ram Kumar
- Virology Laboratory, National Centre for Veterinary Type Cultures, ICAR-National Research Centre on Equines, Hisar, Haryana 125001, India; Department of Veterinary Microbiology and Biotechnology, Rajasthan University of Veterinary and Animal Sciences, Bikaner, Rajasthan 334001, India
| | - Nitin Khandelwal
- Virology Laboratory, National Centre for Veterinary Type Cultures, ICAR-National Research Centre on Equines, Hisar, Haryana 125001, India
| | - Riyesh Thachamvally
- Virology Laboratory, National Centre for Veterinary Type Cultures, ICAR-National Research Centre on Equines, Hisar, Haryana 125001, India
| | - Bhupendra Nath Tripathi
- Virology Laboratory, National Centre for Veterinary Type Cultures, ICAR-National Research Centre on Equines, Hisar, Haryana 125001, India
| | - Sanjay Barua
- Virology Laboratory, National Centre for Veterinary Type Cultures, ICAR-National Research Centre on Equines, Hisar, Haryana 125001, India
| | - Sudhir Kumar Kashyap
- Department of Veterinary Microbiology and Biotechnology, Rajasthan University of Veterinary and Animal Sciences, Bikaner, Rajasthan 334001, India
| | - Sunil Maherchandani
- Department of Veterinary Microbiology and Biotechnology, Rajasthan University of Veterinary and Animal Sciences, Bikaner, Rajasthan 334001, India
| | - Naveen Kumar
- Virology Laboratory, National Centre for Veterinary Type Cultures, ICAR-National Research Centre on Equines, Hisar, Haryana 125001, India.
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Roles of the 5' Untranslated Region of Nonprimate Hepacivirus in Translation Initiation and Viral Replication. J Virol 2018; 92:JVI.01997-17. [PMID: 29343570 DOI: 10.1128/jvi.01997-17] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 01/09/2018] [Indexed: 12/26/2022] Open
Abstract
The 5' untranslated region (UTR) of hepatitis C virus (HCV), which is composed of four domains (I, II, III, and IV) and a pseudoknot, is essential for translation and viral replication. Equine nonprimate hepacivirus (EHcV) harbors a 5' UTR consisting of a large 5'-terminal domain (I); three additional domains (I', II, and III), which are homologous to domains I, II, and III, respectively, of HCV; and a pseudoknot, in the order listed. In this study, we investigated the roles of the EHcV 5' UTR in translation and viral replication. The internal ribosome entry site (IRES) activity of the EHcV 5' UTR was lower than that of the HCV 5' UTR in several cell lines due to structural differences in domain III. Domains I and III of EHcV were functional in the HCV 5' UTR in terms of IRES activity and the replication of the subgenomic replicon (SGR), although domain II was not exchangeable between EHcV and HCV for SGR replication. Furthermore, the region spanning domains I and I' of EHcV (the 5'-proximal EHcV-specific region) improved RNA stability and provided the HCV SGR with microRNA 122 (miR-122)-independent replication capability, while EHcV domain I alone improved SGR replication and RNA stability irrespective of miR-122. These data suggest that the region spanning EHcV domains I and I' improves RNA stability and viral replication regardless of miR-122 expression. The 5'-proximal EHcV-specific region may represent an inherent mechanism to facilitate viral replication in nonhepatic tissues.IMPORTANCE EHcV is the closest viral homolog to HCV among other hepaciviruses. HCV exhibits a narrow host range and liver-specific tropism, while epidemiological reports suggest that EHcV infects the liver and respiratory organs in horses, donkeys, and dogs. However, the mechanism explaining the differences in host or organ tropism between HCV and EHcV is unknown. In this study, our data suggest that the 5' untranslated region (UTR) of EHcV is composed of an internal ribosome entry site (IRES) element that is functionally exchangeable with HCV IRES elements. Furthermore, the 5'-proximal EHcV-specific region enhances viral replication and RNA stability in a miR-122-independent manner. Our data suggest that the region upstream of domain II in the EHcV 5' UTR contributes to the differences in tissue tropism observed between these hepaciviruses.
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18
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Arrangements of nucleotides flanking the start codon in the IRES of the hepatitis C virus in the IRES binary complex with the human 40S ribosomal subunit. Biochimie 2018; 148:72-79. [PMID: 29501734 DOI: 10.1016/j.biochi.2018.02.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 02/26/2018] [Indexed: 01/09/2023]
Abstract
Genomic RNA of hepatitis C virus (HCV) has an internal ribosome entry site (IRES), a specific highly structured fragment responsible for its non-canonical translation initiation. The HCV IRES contains a major part of the 5'-untranslated region of the viral RNA and a small portion of the open reading frame (ORF). At the first step of initiation, IRES directly binds to 40S ribosomal subunits so that the AUG start codon appears at the P site region without scanning and without involving initiation factors. However, it is still not entirely clear whether the IRES ORF is correctly loaded into the 40S ribosomal mRNA binding channel in the resulting binary complex. To address this issue, we applied site-directed cross-linking using HCV IRES derivatives bearing a perfluorophenyl azide cross-linker at nucleotides in definite positions relative to the adenine of the AUG start codon. We found that the modifier at the IRES position -3 cross-links to ribosomal proteins uS11 and eS26. These proteins have been identified together with uS7 as those interacting with the mRNA nucleotide in position -3 relative to the first nucleotide of the codon directed to the P site by a cognate tRNA. Thus, our results indicate a certain difference in the locations of the above parts of HCV IRES and canonical mRNAs on 40S subunits. The modifier at the IRES positions +4/5 was attached to uS19, which is specific for ribosomal complexes with the P site tRNA and similar derivatives of model canonical mRNAs when the modifier is in the same positions. However, the cross-linking efficiency of the IRES derivative was drastically lower than that previously observed with derivatives of model mRNAs. This implies that the IRES ORF portion is correctly loaded into the mRNA binding channel only in a tiny fraction of the binary complexes.
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19
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Mailliot J, Martin F. Viral internal ribosomal entry sites: four classes for one goal. WILEY INTERDISCIPLINARY REVIEWS. RNA 2018; 9. [PMID: 29193740 DOI: 10.1002/wrna.1458] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 09/19/2017] [Accepted: 10/02/2017] [Indexed: 12/22/2022]
Abstract
To ensure efficient propagation, viruses need to rapidly produce viral proteins after cell entrance. Since viral genomes do not encode any components of the protein biosynthesis machinery, viral proteins must be produced by the host cell. To hi-jack the host cellular translation, viruses use a great variety of distinct strategies. Many single-stranded positive-sensed RNA viruses contain so-called internal ribosome entry sites (IRESs). IRESs are structural RNA motifs that have evolved to specific folds that recruit the host ribosomes on the viral coding sequences in order to synthesize viral proteins. In host canonical translation, recruitment of the translation machinery components is essentially guided by the 5' cap (m7 G) of mRNA. In contrast, IRESs are able to promote efficient ribosome assembly internally and in cap-independent manner. IRESs have been categorized into four classes, based on their length, nucleotide sequence, secondary and tertiary structures, as well as their mode of action. Classes I and II require the assistance of cellular auxiliary factors, the eukaryotic intiation factors (eIF), for efficient ribosome assembly. Class III IRESs require only a subset of eIFs whereas Class IV, which are the more compact, can promote translation without any eIFs. Extensive functional and structural investigations of IRESs over the past decades have allowed a better understanding of their mode of action for viral translation. Because viral translation has a pivotal role in the infectious program, IRESs are therefore attractive targets for therapeutic purposes. WIREs RNA 2018, 9:e1458. doi: 10.1002/wrna.1458 This article is categorized under: Translation > Ribosome Structure/Function Translation > Translation Mechanisms RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes.
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Affiliation(s)
- Justine Mailliot
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS UMR7104, INSERM U964, Illkirch-Graffenstaden, France
| | - Franck Martin
- Institut de Biologie Moléculaire et Cellulaire, "Architecture et Réactivité de l'ARN" CNRS UPR9002, Université De Strasbourg, Strasbourg, France
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20
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Martinez-Salas E, Francisco-Velilla R, Fernandez-Chamorro J, Embarek AM. Insights into Structural and Mechanistic Features of Viral IRES Elements. Front Microbiol 2018; 8:2629. [PMID: 29354113 PMCID: PMC5759354 DOI: 10.3389/fmicb.2017.02629] [Citation(s) in RCA: 98] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 12/15/2017] [Indexed: 01/19/2023] Open
Abstract
Internal ribosome entry site (IRES) elements are cis-acting RNA regions that promote internal initiation of protein synthesis using cap-independent mechanisms. However, distinct types of IRES elements present in the genome of various RNA viruses perform the same function despite lacking conservation of sequence and secondary RNA structure. Likewise, IRES elements differ in host factor requirement to recruit the ribosomal subunits. In spite of this diversity, evolutionarily conserved motifs in each family of RNA viruses preserve sequences impacting on RNA structure and RNA–protein interactions important for IRES activity. Indeed, IRES elements adopting remarkable different structural organizations contain RNA structural motifs that play an essential role in recruiting ribosomes, initiation factors and/or RNA-binding proteins using different mechanisms. Therefore, given that a universal IRES motif remains elusive, it is critical to understand how diverse structural motifs deliver functions relevant for IRES activity. This will be useful for understanding the molecular mechanisms beyond cap-independent translation, as well as the evolutionary history of these regulatory elements. Moreover, it could improve the accuracy to predict IRES-like motifs hidden in genome sequences. This review summarizes recent advances on the diversity and biological relevance of RNA structural motifs for viral IRES elements.
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Affiliation(s)
- Encarnacion Martinez-Salas
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas - Universidad Autónoma de Madrid, Madrid, Spain
| | - Rosario Francisco-Velilla
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas - Universidad Autónoma de Madrid, Madrid, Spain
| | - Javier Fernandez-Chamorro
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas - Universidad Autónoma de Madrid, Madrid, Spain
| | - Azman M Embarek
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas - Universidad Autónoma de Madrid, Madrid, Spain
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21
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Romero-López C, Berzal-Herranz A. The 5BSL3.2 Functional RNA Domain Connects Distant Regions in the Hepatitis C Virus Genome. Front Microbiol 2017; 8:2093. [PMID: 29163393 PMCID: PMC5671509 DOI: 10.3389/fmicb.2017.02093] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 10/12/2017] [Indexed: 02/05/2023] Open
Abstract
Viral genomes are complexly folded entities that carry all the information required for the infective cycle. The nucleotide sequence of the RNA virus genome encodes proteins and functional information contained in discrete, highly conserved structural units. These so-called functional RNA domains play essential roles in the progression of infection, which requires their preservation from one generation to the next. Numerous functional RNA domains exist in the genome of the hepatitis C virus (HCV). Among them, the 5BSL3.2 domain in the cis-acting replication element (CRE) at the 3' end of the viral open reading frame has become of particular interest given its role in HCV RNA replication and as a regulator of viral protein synthesis. These functionalities are achieved via the establishment of a complex network of long-distance RNA-RNA contacts involving (at least as known to date) the highly conserved 3'X tail, the apical loop of domain IIId in the internal ribosome entry site, and/or the so-called Alt region upstream of the CRE. Changing contacts promotes the execution of different stages of the viral cycle. The 5BSL3.2 domain thus operates at the core of a system that governs the progression of HCV infection. This review summarizes our knowledge of the long-range RNA-RNA interaction network in the HCV genome, with special attention paid to the structural and functional consequences derived from the establishment of different contacts. The potential implications of such interactions in switching between the different stages of the viral cycle are discussed.
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Affiliation(s)
- Cristina Romero-López
- Instituto de Parasitología y Biomedicina “López-Neyra”, Consejo Superior de Investigaciones Científicas (IPBLN-CSIC), Granada, Spain
| | - Alfredo Berzal-Herranz
- Instituto de Parasitología y Biomedicina “López-Neyra”, Consejo Superior de Investigaciones Científicas (IPBLN-CSIC), Granada, Spain
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22
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Mengardi C, Limousin T, Ricci EP, Soto-Rifo R, Decimo D, Ohlmann T. microRNAs stimulate translation initiation mediated by HCV-like IRESes. Nucleic Acids Res 2017; 45:4810-4824. [PMID: 28077561 PMCID: PMC5416841 DOI: 10.1093/nar/gkw1345] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 12/22/2016] [Indexed: 01/04/2023] Open
Abstract
MicroRNAs (miRNAs) are small non-coding RNAs that control gene expression by recognizing and hybridizing to a specific sequence generally located in the 3΄ untranslated region (UTR) of targeted mRNAs. miRNA-induced inhibition of translation occurs during the initiation step, most probably at the level of ribosome scanning. In this process, the RNA-induced silencing complex interacts both with PABP and the 43S pre-initiation complex to disrupt scanning of the 40S ribosome. However, in some specific cases, miRNAs can stimulate translation. Although the mechanism of miRNA-mediated upregulation is unknown, it appears that the poly(A) tail and the lack of availability of the TNRC6 proteins are amongst major determinants. The genomic RNA of the Hepatitis C Virus is uncapped, non-polyadenylated and harbors a peculiar internal ribosome entry site (IRES) that binds the ribosome directly to the AUG codon. Thus, we have exploited the unique properties of the HCV IRES and other related IRESes (HCV-like) to study how translation initiation can be modulated by miRNAs on these elements. Here, we report that miRNA binding to the 3΄ UTR can stimulate translation of a reporter gene given that its expression is driven by an HCV-like IRES and that it lacks a poly(A) tail at its 3΄ extremity.
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Affiliation(s)
- Chloé Mengardi
- CIRI, International Center for Infectiology Research, Université de Lyon, 69364 Lyon, France.,INSERM, U1111, Lyon, France.,Ecole Normale Supérieure de Lyon, Lyon, France.,Université Lyon 1, Centre International de Recherche en Infectiologie, Lyon, France.,CNRS, UMR5308, Lyon, France
| | - Taran Limousin
- CIRI, International Center for Infectiology Research, Université de Lyon, 69364 Lyon, France.,INSERM, U1111, Lyon, France.,Ecole Normale Supérieure de Lyon, Lyon, France.,Université Lyon 1, Centre International de Recherche en Infectiologie, Lyon, France.,CNRS, UMR5308, Lyon, France
| | - Emiliano P Ricci
- CIRI, International Center for Infectiology Research, Université de Lyon, 69364 Lyon, France.,INSERM, U1111, Lyon, France.,Ecole Normale Supérieure de Lyon, Lyon, France.,Université Lyon 1, Centre International de Recherche en Infectiologie, Lyon, France.,CNRS, UMR5308, Lyon, France
| | - Ricardo Soto-Rifo
- CIRI, International Center for Infectiology Research, Université de Lyon, 69364 Lyon, France.,INSERM, U1111, Lyon, France.,Ecole Normale Supérieure de Lyon, Lyon, France.,Université Lyon 1, Centre International de Recherche en Infectiologie, Lyon, France.,CNRS, UMR5308, Lyon, France
| | - Didier Decimo
- CIRI, International Center for Infectiology Research, Université de Lyon, 69364 Lyon, France.,INSERM, U1111, Lyon, France.,Ecole Normale Supérieure de Lyon, Lyon, France.,Université Lyon 1, Centre International de Recherche en Infectiologie, Lyon, France.,CNRS, UMR5308, Lyon, France
| | - Théophile Ohlmann
- CIRI, International Center for Infectiology Research, Université de Lyon, 69364 Lyon, France.,INSERM, U1111, Lyon, France.,Ecole Normale Supérieure de Lyon, Lyon, France.,Université Lyon 1, Centre International de Recherche en Infectiologie, Lyon, France.,CNRS, UMR5308, Lyon, France
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23
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Kranawetter C, Brady S, Sun L, Schroeder M, Chen SJ, Heng X. Nuclear Magnetic Resonance Study of RNA Structures at the 3'-End of the Hepatitis C Virus Genome. Biochemistry 2017; 56:4972-4984. [PMID: 28829576 DOI: 10.1021/acs.biochem.7b00573] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The 3'-end of the genomic RNA of the hepatitis C virus (HCV) embeds conserved elements that regulate viral RNA synthesis and protein translation by mechanisms that have yet to be elucidated. Previous studies with oligo-RNA fragments have led to multiple, mutually exclusive secondary structure predictions, indicating that HCV RNA structure may be context-dependent. Here we employed a nuclear magnetic resonance (NMR) approach that involves long-range adenosine interaction detection, coupled with site-specific 2H labeling, to probe the structure of the intact 3'-end of the HCV genome (385 nucleotides). Our data reveal that the 3'-end exists as an equilibrium mixture of two conformations: an open conformation in which the 98 nucleotides of the 3'-tail (3'X) form a two-stem-loop structure with the kissing-loop residues sequestered and a closed conformation in which the 3'X rearranges its structure and forms a long-range kissing-loop interaction with an upstream cis-acting element 5BSL3.2. The long-range kissing species is favored under high-Mg2+ conditions, and the intervening sequences do not affect the equilibrium as their secondary structures remain unchanged. The open and closed conformations are consistent with the reported function regulation of viral RNA synthesis and protein translation, respectively. Our NMR detection of these RNA conformations and the structural equilibrium in the 3'-end of the HCV genome support its roles in coordinating various steps of HCV replication.
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Affiliation(s)
- Clayton Kranawetter
- Department of Biochemistry, University of Missouri , Columbia, Missouri 65211, United States
| | - Samantha Brady
- Department of Biochemistry, University of Missouri , Columbia, Missouri 65211, United States
| | - Lizhen Sun
- Department of Physics, Department of Biochemistry, and Informatics Institute, University of Missouri , Columbia, Missouri 65211, United States
| | - Mark Schroeder
- Department of Biochemistry, University of Missouri , Columbia, Missouri 65211, United States
| | - Shi-Jie Chen
- Department of Physics, Department of Biochemistry, and Informatics Institute, University of Missouri , Columbia, Missouri 65211, United States
| | - Xiao Heng
- Department of Biochemistry, University of Missouri , Columbia, Missouri 65211, United States
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Development of Optimized Inhibitor RNAs Allowing Multisite-Targeting of the HCV Genome. Molecules 2017; 22:molecules22050861. [PMID: 28531161 PMCID: PMC6154567 DOI: 10.3390/molecules22050861] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Revised: 05/12/2017] [Accepted: 05/16/2017] [Indexed: 02/07/2023] Open
Abstract
Engineered multivalent drugs are promising candidates for fighting infection by highly variable viruses, such as HCV. The combination into a single molecule of more than one inhibitory domain, each with its own target specificity and even a different mechanism of action, results in drugs with potentially enhanced therapeutic properties. In the present work, the anti-HCV chimeric inhibitor RNA HH363-10, which has a hammerhead catalytic domain and an aptamer RNA domain, was subjected to an in vitro selection strategy to isolate ten different optimised chimeric inhibitor RNAs. The catalytic domain was preserved while the aptamer RNA domain was evolved to contain two binding sites, one mapping to the highly conserved IIIf domain of the HCV genome’s internal ribosome entry site (IRES), and the other either to IRES domain IV (which contains the translation start codon) or the essential linker region between domains I and II. These chimeric molecules efficiently and specifically interfered with HCV IRES-dependent translation in vitro (with IC50 values in the low µM range). They also inhibited both viral translation and replication in cell culture. These findings highlight the feasibility of using in vitro selection strategies for obtaining improved RNA molecules with potential clinical applications.
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25
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The chaperone-like activity of the hepatitis C virus IRES and CRE elements regulates genome dimerization. Sci Rep 2017; 7:43415. [PMID: 28233845 PMCID: PMC5324077 DOI: 10.1038/srep43415] [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: 09/02/2016] [Accepted: 01/24/2017] [Indexed: 02/08/2023] Open
Abstract
The RNA genome of the hepatitis C virus (HCV) establishes a network of long-distance RNA-RNA interactions that direct the progression of the infective cycle. This work shows that the dimerization of the viral genome, which is initiated at the dimer linkage sequence (DLS) within the 3′UTR, is promoted by the CRE region, while the IRES is a negative regulatory partner. Using differential 2′-acylation probing (SHAPE-dif) and molecular interference (HMX) technologies, the CRE activity was found to mainly lie in the critical 5BSL3.2 domain, while the IRES-mediated effect is dependent upon conserved residues within the essential structural elements JIIIabc, JIIIef and PK2. These findings support the idea that, along with the DLS motif, the IRES and CRE are needed to control HCV genome dimerization. They also provide evidences of a novel function for these elements as chaperone-like partners that fine-tune the architecture of distant RNA domains within the HCV genome.
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Jaafar ZA, Oguro A, Nakamura Y, Kieft JS. Translation initiation by the hepatitis C virus IRES requires eIF1A and ribosomal complex remodeling. eLife 2016; 5. [PMID: 28009256 PMCID: PMC5238962 DOI: 10.7554/elife.21198] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 12/22/2016] [Indexed: 12/16/2022] Open
Abstract
Internal ribosome entry sites (IRESs) are important RNA-based translation initiation signals, critical for infection by many pathogenic viruses. The hepatitis C virus (HCV) IRES is the prototype for the type 3 IRESs and is also invaluable for exploring principles of eukaryotic translation initiation, in general. Current mechanistic models for the type 3 IRESs are useful but they also present paradoxes, including how they can function both with and without eukaryotic initiation factor (eIF) 2. We discovered that eIF1A is necessary for efficient activity where it stabilizes tRNA binding and inspects the codon-anticodon interaction, especially important in the IRES' eIF2-independent mode. These data support a model in which the IRES binds preassembled translation preinitiation complexes and remodels them to generate eukaryotic initiation complexes with bacterial-like features. This model explains previous data, reconciles eIF2-dependent and -independent pathways, and illustrates how RNA structure-based control can respond to changing cellular conditions.
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Affiliation(s)
- Zane A Jaafar
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, United States
| | - Akihiro Oguro
- Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | | | - Jeffrey S Kieft
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, United States.,RNA BioScience Initiative, University of Colorado Denver School of Medicine, Aurora, United States
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27
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Hadsbjerg J, Friis MB, Fahnøe U, Nielsen J, Belsham GJ, Rasmussen TB. Sequence adaptations during growth of rescued classical swine fever viruses in cell culture and within infected pigs. Vet Microbiol 2016; 192:123-134. [PMID: 27527774 DOI: 10.1016/j.vetmic.2016.07.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Revised: 06/24/2016] [Accepted: 07/06/2016] [Indexed: 02/05/2023]
Abstract
Classical swine fever virus (CSFV) causes an economically important disease of swine. Four different viruses were rescued from full-length cloned cDNAs derived from the Paderborn strain of CSFV. Three of these viruses had been modified by mutagenesis (with 7 or 8 nt changes) within stem 2 of the subdomain IIIf of the internal ribosome entry site (IRES) that directs the initiation of protein synthesis. Rescued viruses were inoculated into pigs. The rescued vPader10 virus, without modifications in the IRES, induced clinical disease in pigs that was very similar to that observed previously with the parental field strain and transmission to in-contact pigs occurred. Two sequence reversions, in the NS2 and NS5B coding regions, became dominant within the virus populations in these infected pigs. Rescued viruses, with mutant IRES elements, did not induce disease and only very limited circulation of viral RNA could be detected. However, the animals inoculated with these mutant viruses seroconverted against CSFV. Thus, these mutant viruses were highly attenuated in vivo. All 4 rescued viruses were also passaged up to 20 times in cell culture. Using full genome sequencing, the same two adaptations within each of four independent virus populations were observed that restored the coding sequence to that of the parental field strain. These adaptations occurred with different kinetics. The combination of reverse genetics and in depth, full genome sequencing provides a powerful approach to analyse virus adaptation and to identify key determinants of viral replication efficiency in cells and within host animals.
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Affiliation(s)
- Johanne Hadsbjerg
- DTU National Veterinary Institute, Technical University of Denmark, Lindholm, Kalvehave 4771, Denmark
| | - Martin B Friis
- DTU National Veterinary Institute, Technical University of Denmark, Lindholm, Kalvehave 4771, Denmark
| | - Ulrik Fahnøe
- DTU National Veterinary Institute, Technical University of Denmark, Lindholm, Kalvehave 4771, Denmark
| | - Jens Nielsen
- DTU National Veterinary Institute, Technical University of Denmark, Lindholm, Kalvehave 4771, Denmark
| | - Graham J Belsham
- DTU National Veterinary Institute, Technical University of Denmark, Lindholm, Kalvehave 4771, Denmark.
| | - Thomas Bruun Rasmussen
- DTU National Veterinary Institute, Technical University of Denmark, Lindholm, Kalvehave 4771, Denmark
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28
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Lozano G, Jimenez-Aparicio R, Herrero S, Martinez-Salas E. Fingerprinting the junctions of RNA structure by an open-paddlewheel diruthenium compound. RNA (NEW YORK, N.Y.) 2016; 22:330-8. [PMID: 26759454 PMCID: PMC4748811 DOI: 10.1261/rna.054353.115] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Accepted: 12/05/2015] [Indexed: 05/17/2023]
Abstract
RNA function is determined by its structural organization. The RNA structure consists of the combination of distinct secondary structure motifs connected by junctions that play an essential role in RNA folding. Selective 2'-hydroxyl acylation analyzed by primer extension (SHAPE) probing is an established methodology to analyze the secondary structure of long RNA molecules in solution, which provides accurate data about unpaired nucleotides. However, the residues located at the junctions of RNA structures usually remain undetected. Here we report an RNA probing method based on the use of a novel open-paddlewheel diruthenium (OPW-Ru) compound [Ru2Cl2(µ-DPhF)3(DMSO)] (DPhF = N,N'-diphenylformamidinate). This compound has four potential coordination sites in a singular disposition to establish covalent bonds with substrates. As a proof of concept, we have analyzed the reactivity of OPW-Ru toward RNA using two viral internal ribosome entry site (IRES) elements whose function depends on the structural organization of the molecule. Our study suggests that the compound OPW-Ru preferentially attacks at positions located one or two nucleotides away from junctions or bulges of the RNA structure. The OPW-Ru fingerprinting data differ from that obtained by other chemical reagents and provides new information about RNA structure features.
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Affiliation(s)
- Gloria Lozano
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Madrid 28049, Spain
| | - Reyes Jimenez-Aparicio
- Departamento de Química Inorgánica, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Madrid 28040, Spain
| | - Santiago Herrero
- Departamento de Química Inorgánica, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Madrid 28040, Spain
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29
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Thakor N, Smith MD, Roberts L, Faye MD, Patel H, Wieden HJ, Cate JHD, Holcik M. Cellular mRNA recruits the ribosome via eIF3-PABP bridge to initiate internal translation. RNA Biol 2016; 14:553-567. [PMID: 26828225 PMCID: PMC5449081 DOI: 10.1080/15476286.2015.1137419] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
IRES-mediated translation of key cell fate regulating genes has been implicated in tumorigenesis. Concerted action of canonical eukaryotic initiation factors and IRES transacting factors (ITAFs) was shown to regulate cellular IRES mediated translation; however, the precise molecular mechanism of ribosome recruitment to cellular IRESes remains unclear. Here we show that the X-linked inhibitor of apoptosis (XIAP) IRES operates in an evolutionary conserved viral like mode and the structural integrity, particularly in the vicinity of AUG, is critical for ribosome recruitment. The binding of eIF3 together with PABP potentiates ribosome recruitment to the IRES. Our data support the model in which eIF3 binds directly to the XIAP IRES RNA in a structure-dependent manner and acts as a scaffold for IRES RNA, PABP and the 40S ribosome.
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Affiliation(s)
- Nehal Thakor
- a Apoptosis Research Center , Children's Hospital of Eastern Ontario Research Institute , Ottawa , Ontario , Canada.,c Department of Chemistry and Biochemistry , Alberta RNA Research and Training Institute, University of Lethbridge , Lethbridge , AB , Canada
| | - M Duane Smith
- d Department of Molecular and Cell Biology , University of California , Berkeley , CA , USA
| | - Luc Roberts
- c Department of Chemistry and Biochemistry , Alberta RNA Research and Training Institute, University of Lethbridge , Lethbridge , AB , Canada
| | - Mame Daro Faye
- a Apoptosis Research Center , Children's Hospital of Eastern Ontario Research Institute , Ottawa , Ontario , Canada
| | - Harshil Patel
- c Department of Chemistry and Biochemistry , Alberta RNA Research and Training Institute, University of Lethbridge , Lethbridge , AB , Canada
| | - Hans-Joachim Wieden
- c Department of Chemistry and Biochemistry , Alberta RNA Research and Training Institute, University of Lethbridge , Lethbridge , AB , Canada
| | - Jamie H D Cate
- d Department of Molecular and Cell Biology , University of California , Berkeley , CA , USA
| | - Martin Holcik
- a Apoptosis Research Center , Children's Hospital of Eastern Ontario Research Institute , Ottawa , Ontario , Canada.,b Department of Pediatrics , University of Ottawa , Ottawa , Ontario , Canada
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30
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Angulo J, Ulryck N, Deforges J, Chamond N, Lopez-Lastra M, Masquida B, Sargueil B. LOOP IIId of the HCV IRES is essential for the structural rearrangement of the 40S-HCV IRES complex. Nucleic Acids Res 2015; 44:1309-25. [PMID: 26626152 PMCID: PMC4756818 DOI: 10.1093/nar/gkv1325] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 11/11/2015] [Indexed: 12/14/2022] Open
Abstract
As obligatory intracellular parasites, viruses rely on cellular machines to complete their life cycle, and most importantly they recruit the host ribosomes to translate their mRNA. The Hepatitis C viral mRNA initiates translation by directly binding the 40S ribosomal subunit in such a way that the initiation codon is correctly positioned in the P site of the ribosome. Such a property is likely to be central for many viruses, therefore the description of host-pathogen interaction at the molecular level is instrumental to provide new therapeutic targets. In this study, we monitored the 40S ribosomal subunit and the viral RNA structural rearrangement induced upon the formation of the binary complex. We further took advantage of an IRES viral mutant mRNA deficient for translation to identify the interactions necessary to promote translation. Using a combination of structure probing in solution and molecular modeling we establish a whole atom model which appears to be very similar to the one obtained recently by cryoEM. Our model brings new information on the complex, and most importantly reveals some structural rearrangement within the ribosome. This study suggests that the formation of a ‘kissing complex’ between the viral RNA and the 18S ribosomal RNA locks the 40S ribosomal subunit in a conformation proficient for translation.
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Affiliation(s)
- Jenniffer Angulo
- CNRS UMR 8015, Laboratoire de cristallographie et RMN Biologiques, Université Paris Descartes, 4 avenue de l'Observatoire, 75270 Paris Cedex 06, France Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Centro de Investigaciones Médicas, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
| | - Nathalie Ulryck
- CNRS UMR 8015, Laboratoire de cristallographie et RMN Biologiques, Université Paris Descartes, 4 avenue de l'Observatoire, 75270 Paris Cedex 06, France
| | - Jules Deforges
- CNRS UMR 8015, Laboratoire de cristallographie et RMN Biologiques, Université Paris Descartes, 4 avenue de l'Observatoire, 75270 Paris Cedex 06, France
| | - Nathalie Chamond
- CNRS UMR 8015, Laboratoire de cristallographie et RMN Biologiques, Université Paris Descartes, 4 avenue de l'Observatoire, 75270 Paris Cedex 06, France
| | - Marcelo Lopez-Lastra
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Centro de Investigaciones Médicas, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
| | - Benoît Masquida
- UMR 7156 Génétique Moléculaire Génomique Microbiologie, CNRS - Université de Strasbourg, Strasbourg, France
| | - Bruno Sargueil
- CNRS UMR 8015, Laboratoire de cristallographie et RMN Biologiques, Université Paris Descartes, 4 avenue de l'Observatoire, 75270 Paris Cedex 06, France
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31
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Yamamoto H, Collier M, Loerke J, Ismer J, Schmidt A, Hilal T, Sprink T, Yamamoto K, Mielke T, Bürger J, Shaikh TR, Dabrowski M, Hildebrand PW, Scheerer P, Spahn CMT. Molecular architecture of the ribosome-bound Hepatitis C Virus internal ribosomal entry site RNA. EMBO J 2015; 34:3042-58. [PMID: 26604301 DOI: 10.15252/embj.201592469] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 10/29/2015] [Indexed: 12/12/2022] Open
Abstract
Internal ribosomal entry sites (IRESs) are structured cis-acting RNAs that drive an alternative, cap-independent translation initiation pathway. They are used by many viruses to hijack the translational machinery of the host cell. IRESs facilitate translation initiation by recruiting and actively manipulating the eukaryotic ribosome using only a subset of canonical initiation factor and IRES transacting factors. Here we present cryo-EM reconstructions of the ribosome 80S- and 40S-bound Hepatitis C Virus (HCV) IRES. The presence of four subpopulations for the 80S•HCV IRES complex reveals dynamic conformational modes of the complex. At a global resolution of 3.9 Å for the most stable complex, a derived atomic model reveals a complex fold of the IRES RNA and molecular details of its interaction with the ribosome. The comparison of obtained structures explains how a modular architecture facilitates mRNA loading and tRNA binding to the P-site. This information provides the structural foundation for understanding the mechanism of HCV IRES RNA-driven translation initiation.
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Affiliation(s)
- Hiroshi Yamamoto
- Institut für Medizinische Physik und Biophysik, Charité - Universitätsmedizin, Berlin, Germany
| | - Marianne Collier
- Institut für Medizinische Physik und Biophysik, Charité - Universitätsmedizin, Berlin, Germany
| | - Justus Loerke
- Institut für Medizinische Physik und Biophysik, Charité - Universitätsmedizin, Berlin, Germany
| | - Jochen Ismer
- Institut für Medizinische Physik und Biophysik, Charité - Universitätsmedizin, Berlin, Germany
| | - Andrea Schmidt
- Institut für Medizinische Physik und Biophysik, Charité - Universitätsmedizin, Berlin, Germany
| | - Tarek Hilal
- Institut für Medizinische Physik und Biophysik, Charité - Universitätsmedizin, Berlin, Germany
| | - Thiemo Sprink
- Institut für Medizinische Physik und Biophysik, Charité - Universitätsmedizin, Berlin, Germany
| | - Kaori Yamamoto
- Institut für Medizinische Physik und Biophysik, Charité - Universitätsmedizin, Berlin, Germany
| | - Thorsten Mielke
- Institut für Medizinische Physik und Biophysik, Charité - Universitätsmedizin, Berlin, Germany UltraStrukturNetzwerk, Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Jörg Bürger
- Institut für Medizinische Physik und Biophysik, Charité - Universitätsmedizin, Berlin, Germany UltraStrukturNetzwerk, Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Tanvir R Shaikh
- Structural Biology Programme, CEITEC, Masaryk University, Brno, Czech Republic
| | - Marylena Dabrowski
- Institut für Medizinische Physik und Biophysik, Charité - Universitätsmedizin, Berlin, Germany
| | - Peter W Hildebrand
- Institut für Medizinische Physik und Biophysik, Charité - Universitätsmedizin, Berlin, Germany
| | - Patrick Scheerer
- Institut für Medizinische Physik und Biophysik, Charité - Universitätsmedizin, Berlin, Germany
| | - Christian M T Spahn
- Institut für Medizinische Physik und Biophysik, Charité - Universitätsmedizin, Berlin, Germany
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32
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Lim NCH, Jackson SE. Molecular knots in biology and chemistry. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:354101. [PMID: 26291690 DOI: 10.1088/0953-8984/27/35/354101] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Knots and entanglements are ubiquitous. Beyond their aesthetic appeal, these fascinating topological entities can be either useful or cumbersome. In recent decades, the importance and prevalence of molecular knots have been increasingly recognised by scientists from different disciplines. In this review, we provide an overview on the various molecular knots found in naturally occurring biological systems (DNA, RNA and proteins), and those created by synthetic chemists. We discuss the current knowledge in these fields, including recent developments in experimental and, in some cases, computational studies which are beginning to shed light into the complex interplay between the structure, formation and properties of these topologically intricate molecules.
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Affiliation(s)
- Nicole C H Lim
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK. Faculty of Sciences, Universiti Brunei Darussalam, Gadong BE 1410, Brunei Darussalam
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33
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Quade N, Boehringer D, Leibundgut M, van den Heuvel J, Ban N. Cryo-EM structure of Hepatitis C virus IRES bound to the human ribosome at 3.9-Å resolution. Nat Commun 2015; 6:7646. [PMID: 26155016 PMCID: PMC4510694 DOI: 10.1038/ncomms8646] [Citation(s) in RCA: 100] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 05/27/2015] [Indexed: 01/10/2023] Open
Abstract
Hepatitis C virus (HCV), a widespread human pathogen, is dependent on a highly structured 5'-untranslated region of its mRNA, referred to as internal ribosome entry site (IRES), for the translation of all of its proteins. The HCV IRES initiates translation by directly binding to the small ribosomal subunit (40S), circumventing the need for many eukaryotic translation initiation factors required for mRNA scanning. Here we present the cryo-EM structure of the human 40S ribosomal subunit in complex with the HCV IRES at 3.9 Å resolution, determined by focused refinement of an 80S ribosome-HCV IRES complex. The structure reveals the molecular details of the interactions between the IRES and the 40S, showing that expansion segment 7 (ES7) of the 18S rRNA acts as a central anchor point for the HCV IRES. The structural data rationalizes previous biochemical and genetic evidence regarding the initiation mechanism of the HCV and other related IRESs.
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Affiliation(s)
- Nick Quade
- Department of Biology, Institute of Molecular Biology and Biophysics, Otto-Stern-Weg 5, ETH Zürich, Zürich 8093, Switzerland
| | - Daniel Boehringer
- Department of Biology, Institute of Molecular Biology and Biophysics, Otto-Stern-Weg 5, ETH Zürich, Zürich 8093, Switzerland
| | - Marc Leibundgut
- Department of Biology, Institute of Molecular Biology and Biophysics, Otto-Stern-Weg 5, ETH Zürich, Zürich 8093, Switzerland
| | - Joop van den Heuvel
- Research Group Recombinant Protein Expression, Helmholtz Centre for Infection Research, Inhoffenstraße 7, Braunschweig 38124, Germany
| | - Nenad Ban
- Department of Biology, Institute of Molecular Biology and Biophysics, Otto-Stern-Weg 5, ETH Zürich, Zürich 8093, Switzerland
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34
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Asnani M, Kumar P, Hellen CUT. Widespread distribution and structural diversity of Type IV IRESs in members of Picornaviridae. Virology 2015; 478:61-74. [PMID: 25726971 DOI: 10.1016/j.virol.2015.02.016] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Revised: 02/05/2015] [Accepted: 02/09/2015] [Indexed: 01/13/2023]
Abstract
Picornavirus genomes contain internal ribosomal entry sites (IRESs) that promote end-independent translation initiation. Five structural classes of picornavirus IRES have been identified, but numerous IRESs remain unclassified. Here, previously unrecognized Type IV IRESs were identified in members of three proposed picornavirus genera (Limnipivirus, Pasivirus, Rafivirus) and four recognized genera (Kobuvirus, Megrivirus, Sapelovirus, Parechovirus). These IRESs are ~230-420 nucleotides long, reflecting heterogeneity outside a common structural core. Closer analysis yielded insights into evolutionary processes that have shaped contemporary IRESs. The presence of related IRESs in diverse genera supports the hypothesis that they are heritable genetic elements that spread by horizontal gene transfer. Recombination likely also accounts for the exchange of some peripheral subdomains, suggesting that IRES evolution involves incremental addition of elements to a pre-existing core. Nucleotide conservation is concentrated in ribosome-binding sites, and at the junction of helical domains, likely to ensure orientation of subdomains in an active conformation.
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Affiliation(s)
- Mukta Asnani
- Department of Cell Biology, State University of New York Downstate Medical Center, Brooklyn, NY 11203, USA
| | - Parimal Kumar
- Department of Cell Biology, State University of New York Downstate Medical Center, Brooklyn, NY 11203, USA
| | - Christopher U T Hellen
- Department of Cell Biology, State University of New York Downstate Medical Center, Brooklyn, NY 11203, USA.
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35
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Bhat P, Shwetha S, Sharma DK, Joseph AP, Srinivasan N, Das S. The beta hairpin structure within ribosomal protein S5 mediates interplay between domains II and IV and regulates HCV IRES function. Nucleic Acids Res 2015; 43:2888-901. [PMID: 25712089 PMCID: PMC4357715 DOI: 10.1093/nar/gkv110] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Translation initiation in Hepatitis C Virus (HCV) is mediated by Internal Ribosome Entry Site (IRES), which is independent of cap-structure and uses a limited number of canonical initiation factors. During translation initiation IRES–40S complex formation depends on high affinity interaction of IRES with ribosomal proteins. Earlier, it has been shown that ribosomal protein S5 (RPS5) interacts with HCV IRES. Here, we have extensively characterized the HCV IRES–RPS5 interaction and demonstrated its role in IRES function. Computational modelling and RNA–protein interaction studies demonstrated that the beta hairpin structure within RPS5 is critically required for the binding with domains II and IV. Mutations disrupting IRES–RPS5 interaction drastically reduced the 80S complex formation and the corresponding IRES activity. Computational analysis and UV cross-linking experiments using various IRES-mutants revealed interplay between domains II and IV mediated by RPS5. In addition, present study demonstrated that RPS5 interaction is unique to HCV IRES and is not involved in 40S–3′ UTR interaction. Further, partial silencing of RPS5 resulted in preferential inhibition of HCV RNA translation. However, global translation was marginally affected by partial silencing of RPS5. Taken together, results provide novel molecular insights into IRES–RPS5 interaction and unravel its functional significance in mediating internal initiation of translation.
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Affiliation(s)
- Prasanna Bhat
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560 012, India
| | - Shivaprasad Shwetha
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560 012, India
| | - Divya Khandige Sharma
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560 012, India
| | | | | | - Saumitra Das
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560 012, India
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36
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Kuehnert J, Sommer G, Zierk AW, Fedarovich A, Brock A, Fedarovich D, Heise T. Novel RNA chaperone domain of RNA-binding protein La is regulated by AKT phosphorylation. Nucleic Acids Res 2015; 43:581-94. [PMID: 25520193 PMCID: PMC4288197 DOI: 10.1093/nar/gku1309] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2014] [Revised: 12/02/2014] [Accepted: 12/04/2014] [Indexed: 01/13/2023] Open
Abstract
The cellular function of the cancer-associated RNA-binding protein La has been linked to translation of viral and cellular mRNAs. Recently, we have shown that the human La protein stimulates IRES-mediated translation of the cooperative oncogene CCND1 in cervical cancer cells. However, there is little known about the underlying molecular mechanism by which La stimulates CCND1 IRES-mediated translation, and we propose that its RNA chaperone activity is required. Herein, we show that La binds close to the CCND1 start codon and demonstrate that La's RNA chaperone activity can change the folding of its binding site. We map the RNA chaperone domain (RCD) within the C-terminal region of La in close proximity to a novel AKT phosphorylation site (T389). Phosphorylation at T389 by AKT-1 strongly impairs its RNA chaperone activity. Furthermore, we demonstrate that the RCD as well as T389 is required to stimulate CCND1 IRES-mediated translation in cells. In summary, we provide a model whereby a novel interplay between RNA-binding, RNA chaperoning and AKT phosphorylation of La protein regulates CCND1 IRES-mediated translation.
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Affiliation(s)
- Julia Kuehnert
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Gunhild Sommer
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Avery W Zierk
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Alena Fedarovich
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Alexander Brock
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Dzmitry Fedarovich
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Tilman Heise
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA
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Xue S, Tian S, Fujii K, Kladwang W, Das R, Barna M. RNA regulons in Hox 5' UTRs confer ribosome specificity to gene regulation. Nature 2015; 517:33-8. [PMID: 25409156 PMCID: PMC4353651 DOI: 10.1038/nature14010] [Citation(s) in RCA: 215] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Accepted: 10/30/2014] [Indexed: 02/07/2023]
Abstract
Emerging evidence suggests that the ribosome has a regulatory function in directing how the genome is translated in time and space. However, how this regulation is encoded in the messenger RNA sequence remains largely unknown. Here we uncover unique RNA regulons embedded in homeobox (Hox) 5' untranslated regions (UTRs) that confer ribosome-mediated control of gene expression. These structured RNA elements, resembling viral internal ribosome entry sites (IRESs), are found in subsets of Hox mRNAs. They facilitate ribosome recruitment and require the ribosomal protein RPL38 for their activity. Despite numerous layers of Hox gene regulation, these IRES elements are essential for converting Hox transcripts into proteins to pattern the mammalian body plan. This specialized mode of IRES-dependent translation is enabled by an additional regulatory element that we term the translation inhibitory element (TIE), which blocks cap-dependent translation of transcripts. Together, these data uncover a new paradigm for ribosome-mediated control of gene expression and organismal development.
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Affiliation(s)
- Shifeng Xue
- Department of Developmental Biology, Stanford University, Stanford, California 94305, USA
- Department of Genetics, Stanford University, Stanford, California 94305, USA
| | - Siqi Tian
- Department of Biochemistry, Stanford University, Stanford, California 94305, USA
| | - Kotaro Fujii
- Department of Developmental Biology, Stanford University, Stanford, California 94305, USA
- Department of Genetics, Stanford University, Stanford, California 94305, USA
| | - Wipapat Kladwang
- Department of Biochemistry, Stanford University, Stanford, California 94305, USA
| | - Rhiju Das
- Department of Biochemistry, Stanford University, Stanford, California 94305, USA
- Department of Physics, Stanford University, Stanford, California 94305, USA
| | - Maria Barna
- Department of Developmental Biology, Stanford University, Stanford, California 94305, USA
- Department of Genetics, Stanford University, Stanford, California 94305, USA
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Khawaja A, Vopalensky V, Pospisek M. Understanding the potential of hepatitis C virus internal ribosome entry site domains to modulate translation initiation via their structure and function. WILEY INTERDISCIPLINARY REVIEWS-RNA 2014; 6:211-24. [PMID: 25352252 PMCID: PMC4361049 DOI: 10.1002/wrna.1268] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/14/2014] [Revised: 08/31/2014] [Accepted: 09/02/2014] [Indexed: 12/16/2022]
Abstract
Translation initiation in the hepatitis C virus (HCV) occurs through a cap-independent mechanism that involves an internal ribosome entry site (IRES) capable of interacting with and utilizing the eukaryotic translational machinery. In this review, we focus on the structural configuration of the different HCV IRES domains and the impact of IRES primary sequence variations on secondary structure conservation and function. In some cases, multiple mutations, even those scattered across different domains, led to restoration of the translational activity of the HCV IRES, although the individual occurrences of these mutations were found to be deleterious. We propose that such observation may be attributed to probable long-range inter- and/or intra-domain functional interactions. The precise functioning of the HCV IRES requires the specific interaction of its domains with ribosomal subunits and a subset of eukaryotic translation initiation factors (eIFs). The structural conformation, sequence preservation and variability, and translational machinery association with the HCV IRES regions are also thoroughly discussed, along with other factors that can affect and influence the formation of translation initiation complexes. WIREs RNA 2015, 6:211–224. doi: 10.1002/wrna.1268
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Affiliation(s)
- Anas Khawaja
- Department of Genetics and Microbiology, Faculty of Science, Charles University in Prague, Prague 2, Czech Republic
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Au HHT, Jan E. Novel viral translation strategies. WILEY INTERDISCIPLINARY REVIEWS-RNA 2014; 5:779-801. [PMID: 25045163 PMCID: PMC7169809 DOI: 10.1002/wrna.1246] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Revised: 05/03/2014] [Accepted: 05/08/2014] [Indexed: 01/06/2023]
Abstract
Viral genomes are compact and encode a limited number of proteins. Because they do not encode components of the translational machinery, viruses exhibit an absolute dependence on the host ribosome and factors for viral messenger RNA (mRNA) translation. In order to recruit the host ribosome, viruses have evolved unique strategies to either outcompete cellular transcripts that are efficiently translated by the canonical translation pathway or to reroute translation factors and ribosomes to the viral genome. Furthermore, viruses must evade host antiviral responses and escape immune surveillance. This review focuses on some recent major findings that have revealed unconventional strategies that viruses utilize, which include usurping the host translational machinery, modulating canonical translation initiation factors to specifically enhance or repress overall translation for the purpose of viral production, and increasing viral coding capacity. The discovery of these diverse viral strategies has provided insights into additional translational control mechanisms and into the viral host interactions that ensure viral protein synthesis and replication. WIREs RNA 2014, 5:779–801. doi: 10.1002/wrna.1246 This article is categorized under:
Translation > Translation Mechanisms Translation > Translation Regulation
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Affiliation(s)
- Hilda H T Au
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, Canada
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40
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Romero-López C, Berzal-Herranz A. Structure-function relationship in viral RNA genomes: The case of hepatitis C virus. World J Med Genet 2014; 4:6-18. [DOI: 10.5496/wjmg.v4.i2.6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 01/23/2014] [Accepted: 04/03/2014] [Indexed: 02/06/2023] Open
Abstract
The acquisition of a storage information system beyond the nucleotide sequence has been a crucial issue for the propagation and dispersion of RNA viruses. This system is composed by highly conserved, complex structural units in the genomic RNA, termed functional RNA domains. These elements interact with other regions of the viral genome and/or proteins to direct viral translation, replication and encapsidation. The genomic RNA of the hepatitis C virus (HCV) is a good model for investigating about conserved structural units. It contains functional domains, defined by highly conserved structural RNA motifs, mostly located in the 5’-untranslatable regions (5’UTRs) and 3’UTR, but also occupying long stretches of the coding sequence. Viral translation initiation is mediated by an internal ribosome entry site located at the 5’ terminus of the viral genome and regulated by distal functional RNA domains placed at the 3’ end. Subsequent RNA replication strongly depends on the 3’UTR folding and is also influenced by the 5’ end of the HCV RNA. Further increase in the genome copy number unleashes the formation of homodimers by direct interaction of two genomic RNA molecules, which are finally packed and released to the extracellular medium. All these processes, as well as transitions between them, are controlled by structural RNA elements that establish a complex, direct and long-distance RNA-RNA interaction network. This review summarizes current knowledge about functional RNA domains within the HCV RNA genome and provides an overview of the control exerted by direct, long-range RNA-RNA contacts for the execution of the viral cycle.
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Abstract
Epstein-Barr virus (EBV) is a tumorigenic human γ-herpesvirus, which produces several known structured RNAs with functional importance: two are implicated in latency maintenance and tumorigenic phenotypes, EBER1 and EBER2; a viral small nucleolar RNA (v-snoRNA1) that may generate a small regulatory RNA; and an internal ribosomal entry site in the EBNA1 mRNA. A recent bioinformatics and RNA-Seq study of EBV identified two novel EBV non-coding (nc)RNAs with evolutionary conservation in lymphocryptoviruses and likely functional importance. Both RNAs are transcribed from a repetitive region of the EBV genome (the W repeats) during a highly oncogenic type of viral latency. One novel ncRNA can form a massive (586 nt) hairpin, while the other RNA is generated from a short (81 nt) intron and is found in high abundance in EBV-infected cells.
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Affiliation(s)
- Walter N Moss
- Howard Hughes Medical Institute; Yale University; Department of Molecular Biophysics and Biochemistry; New Haven, CT USA
| | - Nara Lee
- Howard Hughes Medical Institute; Yale University; Department of Molecular Biophysics and Biochemistry; New Haven, CT USA
| | - Genaro Pimienta
- Howard Hughes Medical Institute; Yale University; Department of Molecular Biophysics and Biochemistry; New Haven, CT USA
| | - Joan A Steitz
- Howard Hughes Medical Institute; Yale University; Department of Molecular Biophysics and Biochemistry; New Haven, CT USA
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Viral IRES prediction system - a web server for prediction of the IRES secondary structure in silico. PLoS One 2013; 8:e79288. [PMID: 24223923 PMCID: PMC3818432 DOI: 10.1371/journal.pone.0079288] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2013] [Accepted: 09/22/2013] [Indexed: 02/06/2023] Open
Abstract
The internal ribosomal entry site (IRES) functions as cap-independent translation initiation sites in eukaryotic cells. IRES elements have been applied as useful tools for bi-cistronic expression vectors. Current RNA structure prediction programs are unable to predict precisely the potential IRES element. We have designed a viral IRES prediction system (VIPS) to perform the IRES secondary structure prediction. In order to obtain better results for the IRES prediction, the VIPS can evaluate and predict for all four different groups of IRESs with a higher accuracy. RNA secondary structure prediction, comparison, and pseudoknot prediction programs were implemented to form the three-stage procedure for the VIPS. The backbone of VIPS includes: the RNAL fold program, aimed to predict local RNA secondary structures by minimum free energy method; the RNA Align program, intended to compare predicted structures; and pknotsRG program, used to calculate the pseudoknot structure. VIPS was evaluated by using UTR database, IRES database and Virus database, and the accuracy rate of VIPS was assessed as 98.53%, 90.80%, 82.36% and 80.41% for IRES groups 1, 2, 3, and 4, respectively. This advance useful search approach for IRES structures will facilitate IRES related studies. The VIPS on-line website service is available at http://140.135.61.250/vips/.
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Romero-López C, Berzal-Herranz A. Unmasking the information encoded as structural motifs of viral RNA genomes: a potential antiviral target. Rev Med Virol 2013; 23:340-54. [PMID: 23983005 PMCID: PMC7169113 DOI: 10.1002/rmv.1756] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Revised: 07/23/2013] [Accepted: 07/24/2013] [Indexed: 02/05/2023]
Abstract
RNA viruses show enormous capacity to evolve and adapt to new cellular and molecular contexts, a consequence of mutations arising from errors made by viral RNA-dependent RNA polymerase during replication. Sequence variation must occur, however, without compromising functions essential for the completion of the viral cycle. RNA viruses are safeguarded in this respect by their genome carrying conserved information that does not code only for proteins but also for the formation of structurally conserved RNA domains that directly perform these critical functions. Functional RNA domains can interact with other regions of the viral genome and/or proteins to direct viral translation, replication and encapsidation. They are therefore potential targets for novel therapeutic strategies. This review summarises our knowledge of the functional RNA domains of human RNA viruses and examines the achievements made in the design of antiviral compounds that interfere with their folding and therefore their function.
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Affiliation(s)
- Cristina Romero-López
- Instituto de Parasitología y Biomedicina 'López-Neyra', IPBLN-CSIC, PTS Granada, Armilla, Granada, Spain
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Romero-López C, Barroso-Deljesus A, García-Sacristán A, Briones C, Berzal-Herranz A. End-to-end crosstalk within the hepatitis C virus genome mediates the conformational switch of the 3'X-tail region. Nucleic Acids Res 2013; 42:567-82. [PMID: 24049069 PMCID: PMC3874160 DOI: 10.1093/nar/gkt841] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The hepatitis C virus (HCV) RNA genome contains multiple structurally conserved domains that make long-distance RNA-RNA contacts important in the establishment of viral infection. Microarray antisense oligonucleotide assays, improved dimethyl sulfate probing methods and 2' acylation chemistry (selective 2'-hydroxyl acylation and primer extension, SHAPE) showed the folding of the genomic RNA 3' end to be regulated by the internal ribosome entry site (IRES) element via direct RNA-RNA interactions. The essential cis-acting replicating element (CRE) and the 3'X-tail region adopted different 3D conformations in the presence and absence of the genomic RNA 5' terminus. Further, the structural transition in the 3'X-tail from the replication-competent conformer (consisting of three stem-loops) to the dimerizable form (with two stem-loops), was found to depend on the presence of both the IRES and the CRE elements. Complex interplay between the IRES, the CRE and the 3'X-tail region would therefore appear to occur. The preservation of this RNA-RNA interacting network, and the maintenance of the proper balance between different contacts, may play a crucial role in the switch between different steps of the HCV cycle.
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Affiliation(s)
- Cristina Romero-López
- Instituto de Parasitología y Biomedicina López-Neyra, IPBLN-CSIC, PTS Granada, Avda. del Conocimiento s/n, Armilla, 18016 Granada, Spain, Unidad de Genómica, Instituto de Parasitología y Biomedicina López-Neyra, IPBLN-CSIC, PTS Granada, Avda. del Conocimiento s/n, Armilla, 18016 Granada, Spain, Laboratorio de Evolución Molecular, Centro de Astrobiología (CSIC-INTA), Carretera de Ajalvir km 4, 28850 Torrejón de Ardoz, Madrid, Spain and Centro de Investigación Biomédica en Red de enfermedades hepáticas y digestivas (CIBERehd), Spain
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Bai Y, Zhou K, Doudna JA. Hepatitis C virus 3'UTR regulates viral translation through direct interactions with the host translation machinery. Nucleic Acids Res 2013; 41:7861-74. [PMID: 23783572 PMCID: PMC3763534 DOI: 10.1093/nar/gkt543] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The 3′ untranslated region (3′UTR) of hepatitis C virus (HCV) messenger RNA stimulates viral translation by an undetermined mechanism. We identified a high affinity interaction, conserved among different HCV genotypes, between the HCV 3′UTR and the host ribosome. The 3′UTR interacts with 40S ribosomal subunit proteins residing primarily in a localized region on the 40S solvent-accessible surface near the messenger RNA entry and exit sites. This region partially overlaps with the site where the HCV internal ribosome entry site was found to bind, with the internal ribosome entry site-40S subunit interaction being dominant. Despite its ability to bind to 40S subunits independently, the HCV 3′UTR only stimulates translation in cis, without affecting the first round translation rate. These observations support a model in which the HCV 3′UTR retains ribosome complexes during translation termination to facilitate efficient initiation of subsequent rounds of translation.
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Affiliation(s)
- Yun Bai
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA, Howard Hughes Medical Institute, University of California, Berkeley, CA 94720, USA, Department of Chemistry, University of California, Berkeley, CA 94720, USA and Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
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46
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Ligand-inducible formation of RNA pseudoknot. Bioorg Med Chem Lett 2013; 23:3539-41. [DOI: 10.1016/j.bmcl.2013.04.037] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 04/12/2013] [Accepted: 04/15/2013] [Indexed: 11/23/2022]
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Huang Q, Purzycka KJ, Lusvarghi S, Li D, LeGrice SF, Boeke JD. Retrotransposon Ty1 RNA contains a 5'-terminal long-range pseudoknot required for efficient reverse transcription. RNA (NEW YORK, N.Y.) 2013; 19:320-32. [PMID: 23329695 PMCID: PMC3677243 DOI: 10.1261/rna.035535.112] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Accepted: 11/26/2012] [Indexed: 05/04/2023]
Abstract
Ty1 retrotransposon RNA has the potential to fold into a variety of distinct structures, mutation of which affects retrotransposition frequencies. We show here that one potential functional structure is located at the 5' end of the genome and can assume a pseudoknot conformation. Chemoenzymatic probing of wild-type and mutant mini-Ty1 RNAs supports the existence of such a structure, while molecular genetic analyses show that mutations disrupting pseudoknot formation interfere with retrotransposition, indicating that it provides a critical biological function. These defects are enhanced at higher temperatures. When these mutants are combined with compensatory changes, retrotransposition is restored, consistent with pseudoknot architecture. Analyses of mutants suggest a defect in Ty1 reverse transcription. Collectively, our data allow modeling of a three-dimensional structure for this novel critical cis-acting signal of the Ty1 genome.
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Affiliation(s)
- Qing Huang
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
- The High Throughput Biology Center, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
| | - Katarzyna J. Purzycka
- National Cancer Institute, Frederick, Maryland 21702, USA
- Laboratory of Structural Chemistry of Nucleic Acids, Institute of Bioorganic Chemistry, Polish Academy of Sciences, 61-704 Poznań, Poland
| | | | - Donghui Li
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
- The High Throughput Biology Center, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
| | | | - Jef D. Boeke
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
- The High Throughput Biology Center, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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48
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Mortimer SA, Doudna JA. Unconventional miR-122 binding stabilizes the HCV genome by forming a trimolecular RNA structure. Nucleic Acids Res 2013; 41:4230-40. [PMID: 23416544 PMCID: PMC3627571 DOI: 10.1093/nar/gkt075] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
MicroRNAs (miRNAs) typically downregulate protein expression from target mRNAs through limited base-pairing interactions between the 5′ ‘seed’ region of the miRNA and the mRNA 3′ untranslated region (3′UTR). In contrast to this established mode of action, the liver-specific human miR-122 binds at two sites within the hepatitis C viral (HCV) 5′UTR, leading to increased production of infectious virions. We show here that two copies of miR-122 interact with the HCV 5′UTR at partially overlapping positions near the 5′ end of the viral transcript to form a stable ternary complex. Both miR-122 binding sites involve extensive base pairing outside of the seed sequence; yet, they have substantially different interaction affinities. Structural probing reveals changes in the architecture of the HCV 5′UTR that occur on interaction with miR-122. In contrast to previous reports, however, results using both the recombinant cytoplasmic exonuclease Xrn1 and liver cell extracts show that miR-122-mediated protection of the HCV RNA from degradation does not correlate with stimulation of viral propagation in vivo. Thus, the miR-122:HCV ternary complex likely functions at other steps critical to the viral life cycle.
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Affiliation(s)
- Stefanie A Mortimer
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
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Walsh D, Mathews MB, Mohr I. Tinkering with translation: protein synthesis in virus-infected cells. Cold Spring Harb Perspect Biol 2013; 5:a012351. [PMID: 23209131 DOI: 10.1101/cshperspect.a012351] [Citation(s) in RCA: 178] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Viruses are obligate intracellular parasites, and their replication requires host cell functions. Although the size, composition, complexity, and functions encoded by their genomes are remarkably diverse, all viruses rely absolutely on the protein synthesis machinery of their host cells. Lacking their own translational apparatus, they must recruit cellular ribosomes in order to translate viral mRNAs and produce the protein products required for their replication. In addition, there are other constraints on viral protein production. Crucially, host innate defenses and stress responses capable of inactivating the translation machinery must be effectively neutralized. Furthermore, the limited coding capacity of the viral genome needs to be used optimally. These demands have resulted in complex interactions between virus and host that exploit ostensibly virus-specific mechanisms and, at the same time, illuminate the functioning of the cellular protein synthesis apparatus.
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Affiliation(s)
- Derek Walsh
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA.
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HCV IRES manipulates the ribosome to promote the switch from translation initiation to elongation. Nat Struct Mol Biol 2012; 20:150-8. [PMID: 23262488 PMCID: PMC3864654 DOI: 10.1038/nsmb.2465] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Accepted: 11/12/2012] [Indexed: 12/11/2022]
Abstract
The hepatitis C virus (HCV) internal ribosome entry site (IRES) drives non-canonical initiation of protein synthesis necessary for viral replication. HCV IRES functional studies have focused on 80S ribosome formation, but have not explored roles after the 80S ribosome is poised at the start codon. Here, we report that mutations of an IRES domain that docks in the 40S subunit’s decoding groove and cause only a local perturbation in IRES structure result in conformational changes in the IRES-rabbit 40S subunit complex. Functionally, we find the mutation decreases IRES activity by inhibiting the first ribosome translocation event, and modeling suggests that this effect is through an interaction with a single ribosomal protein. The HCV IRES’ ability to manipulate the ribosome provides insight into how the ribosome’s structure and function can be altered by bound RNAs, including those derived from cellular invaders.
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