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Koma T, Doi N, Le BQ, Kondo T, Ishizue M, Tokaji C, Tsukada C, Adachi A, Nomaguchi M. Involvement of a Rarely Used Splicing SD2b Site in the Regulation of HIV-1 vif mRNA Production as Revealed by a Growth-Adaptive Mutation. Viruses 2023; 15:2424. [PMID: 38140666 PMCID: PMC10747208 DOI: 10.3390/v15122424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 12/09/2023] [Accepted: 12/12/2023] [Indexed: 12/24/2023] Open
Abstract
We have previously reported an HIV-1 mutant designated NL-Y226tac that expresses Vif at an ultra-low level, being replication-defective in high-APOBEC3G cells, such as H9. It carries a synonymous mutation within the splicing SA1 site relative to its parental clone. In order to determine whether a certain mutant(s) emerges during multi-infection cycles, we maintained H9 cells infected with a relatively low or high input of NL-Y226tac for extended time periods. Unexpectedly, we reproducibly identified a g5061a mutation in the SD2b site in the two independent long-term culture experiments that partially increases Vif expression and replication ability. Importantly, the adaptive mutation g5061a was demonstrated to enhance vif mRNA production by activation of the SA1 site mediated through increasing usage of a rarely used SD2b site. In the long-term culture initiated by a high virus input, we additionally found a Y226Fttc mutation at the original Y226tac site in SA1 that fully restores Vif expression and replication ability. As expected, the adaptive mutation Y226Fttc enhances vif mRNA production through increasing the splicing site usage of SA1. Our results here revealed the importance of the SD2b nucleotide sequence in producing vif mRNA involved in the HIV-1 adaptation and of mutual antagonism between Vif and APOBEC3 proteins in HIV-1 adaptation/evolution and survival.
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Affiliation(s)
- Takaaki Koma
- Department of Microbiology, Graduate School of Medicine, Tokushima University, Tokushima 770-8503, Japan; (T.K.); (N.D.); (B.Q.L.); (T.K.)
| | - Naoya Doi
- Department of Microbiology, Graduate School of Medicine, Tokushima University, Tokushima 770-8503, Japan; (T.K.); (N.D.); (B.Q.L.); (T.K.)
| | - Bao Quoc Le
- Department of Microbiology, Graduate School of Medicine, Tokushima University, Tokushima 770-8503, Japan; (T.K.); (N.D.); (B.Q.L.); (T.K.)
| | - Tomoyuki Kondo
- Department of Microbiology, Graduate School of Medicine, Tokushima University, Tokushima 770-8503, Japan; (T.K.); (N.D.); (B.Q.L.); (T.K.)
| | - Mitsuki Ishizue
- Department of Microbiology, Graduate School of Medicine, Tokushima University, Tokushima 770-8503, Japan; (T.K.); (N.D.); (B.Q.L.); (T.K.)
- Faculty of Medicine, Tokushima University, Tokushima 770-8503, Japan
| | - Chiaki Tokaji
- Department of Microbiology, Graduate School of Medicine, Tokushima University, Tokushima 770-8503, Japan; (T.K.); (N.D.); (B.Q.L.); (T.K.)
- Faculty of Medicine, Tokushima University, Tokushima 770-8503, Japan
| | - Chizuko Tsukada
- Department of Microbiology, Graduate School of Medicine, Tokushima University, Tokushima 770-8503, Japan; (T.K.); (N.D.); (B.Q.L.); (T.K.)
- Faculty of Medicine, Tokushima University, Tokushima 770-8503, Japan
| | - Akio Adachi
- Department of Microbiology, Graduate School of Medicine, Tokushima University, Tokushima 770-8503, Japan; (T.K.); (N.D.); (B.Q.L.); (T.K.)
| | - Masako Nomaguchi
- Department of Microbiology, Graduate School of Medicine, Tokushima University, Tokushima 770-8503, Japan; (T.K.); (N.D.); (B.Q.L.); (T.K.)
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2
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Alemrajabi M, Macias Calix K, Assis R. Epistasis-Driven Evolution of the SARS-CoV-2 Secondary Structure. J Mol Evol 2022; 90:429-437. [PMID: 36178491 PMCID: PMC9523185 DOI: 10.1007/s00239-022-10073-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 09/02/2022] [Indexed: 11/25/2022]
Abstract
Epistasis is an evolutionary phenomenon whereby the fitness effect of a mutation depends on the genetic background in which it arises. A key source of epistasis in an RNA molecule is its secondary structure, which contains functionally important topological motifs held together by hydrogen bonds between Watson–Crick (WC) base pairs. Here we study epistasis in the secondary structure of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by examining properties of derived alleles arising from substitution mutations at ancestral WC base-paired and unpaired (UP) sites in 15 conserved topological motifs across the genome. We uncover fewer derived alleles and lower derived allele frequencies at WC than at UP sites, supporting the hypothesis that modifications to the secondary structure are often deleterious. At WC sites, we also find lower derived allele frequencies for mutations that abolish base pairing than for those that yield G·U “wobbles,” illustrating that weak base pairing can partially preserve the integrity of the secondary structure. Last, we show that WC sites under the strongest epistatic constraint reside in a three-stemmed pseudoknot motif that plays an essential role in programmed ribosomal frameshifting, whereas those under the weakest epistatic constraint are located in 3’ UTR motifs that regulate viral replication and pathogenicity. Our findings demonstrate the importance of epistasis in the evolution of the SARS-CoV-2 secondary structure, as well as highlight putative structural and functional targets of different forms of natural selection.
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Affiliation(s)
- Mahsa Alemrajabi
- Department of Physics, Florida Atlantic University, Boca Raton, FL, 33431, USA
| | - Ksenia Macias Calix
- Department of Electrical Engineering and Computer Science, Florida Atlantic University, Boca Raton, FL, 33431, USA
| | - Raquel Assis
- Department of Electrical Engineering and Computer Science, Florida Atlantic University, Boca Raton, FL, 33431, USA.
- Institute for Human Health and Disease Intervention, Florida Atlantic University, Boca Raton, FL, 33431, USA.
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3
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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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4
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Huston NC, Wan H, Strine MS, de Cesaris Araujo Tavares R, Wilen CB, Pyle AM. Comprehensive in vivo secondary structure of the SARS-CoV-2 genome reveals novel regulatory motifs and mechanisms. Mol Cell 2021; 81:584-598.e5. [PMID: 33444546 PMCID: PMC7775661 DOI: 10.1016/j.molcel.2020.12.041] [Citation(s) in RCA: 165] [Impact Index Per Article: 55.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 11/06/2020] [Accepted: 12/21/2020] [Indexed: 02/07/2023]
Abstract
Severe-acute-respiratory-syndrome-related coronavirus 2 (SARS-CoV-2) is the positive-sense RNA virus that causes coronavirus disease 2019 (COVID-19). The genome of SARS-CoV-2 is unique among viral RNAs in its vast potential to form RNA structures, yet as much as 97% of its 30 kilobases have not been structurally explored. Here, we apply a novel long amplicon strategy to determine the secondary structure of the SARS-CoV-2 RNA genome at single-nucleotide resolution in infected cells. Our in-depth structural analysis reveals networks of well-folded RNA structures throughout Orf1ab and reveals aspects of SARS-CoV-2 genome architecture that distinguish it from other RNA viruses. Evolutionary analysis shows that several features of the SARS-CoV-2 genomic structure are conserved across β-coronaviruses, and we pinpoint regions of well-folded RNA structure that merit downstream functional analysis. The native, secondary structure of SARS-CoV-2 presented here is a roadmap that will facilitate focused studies on the viral life cycle, facilitate primer design, and guide the identification of RNA drug targets against COVID-19.
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Affiliation(s)
- Nicholas C Huston
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA
| | - Han Wan
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06511, USA
| | - Madison S Strine
- Department of Laboratory Medicine, Yale School of Medicine, New Haven, CT 06510, USA; Department of Immunobiology, Yale School of Medicine, New Haven, CT 06519, USA
| | | | - Craig B Wilen
- Department of Laboratory Medicine, Yale School of Medicine, New Haven, CT 06510, USA; Department of Immunobiology, Yale School of Medicine, New Haven, CT 06519, USA
| | - Anna Marie Pyle
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06511, USA; Department of Chemistry, Yale University, New Haven, CT 06511, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA.
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5
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Huston NC, Wan H, de Cesaris Araujo Tavares R, Wilen C, Pyle AM. Comprehensive in-vivo secondary structure of the SARS-CoV-2 genome reveals novel regulatory motifs and mechanisms. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2020:2020.07.10.197079. [PMID: 32676598 PMCID: PMC7359520 DOI: 10.1101/2020.07.10.197079] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
SARS-CoV-2 is the positive-sense RNA virus that causes COVID-19, a disease that has triggered a major human health and economic crisis. The genome of SARS-CoV-2 is unique among viral RNAs in its vast potential to form stable RNA structures and yet, as much as 97% of its 30 kilobases have not been structurally explored in the context of a viral infection. Our limited knowledge of SARS-CoV-2 genomic architecture is a fundamental limitation to both our mechanistic understanding of coronavirus life cycle and the development of COVID-19 RNA-based therapeutics. Here, we apply a novel long amplicon strategy to determine for the first time the secondary structure of the SARS-CoV-2 RNA genome probed in infected cells. In addition to the conserved structural motifs at the viral termini, we report new structural features like a conformationally flexible programmed ribosomal frameshifting pseudoknot, and a host of novel RNA structures, each of which highlights the importance of studying viral structures in their native genomic context. Our in-depth structural analysis reveals extensive networks of well-folded RNA structures throughout Orf1ab and reveals new aspects of SARS-CoV-2 genome architecture that distinguish it from other single-stranded, positive-sense RNA viruses. Evolutionary analysis of RNA structures in SARS-CoV-2 shows that several features of its genomic structure are conserved across beta coronaviruses and we pinpoint individual regions of well-folded RNA structure that merit downstream functional analysis. The native, complete secondary structure of SAR-CoV-2 presented here is a roadmap that will facilitate focused studies on mechanisms of replication, translation and packaging, and guide the identification of new RNA drug targets against COVID-19.
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Affiliation(s)
- Nicholas C. Huston
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
| | - Han Wan
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT, USA
| | | | - Craig Wilen
- Department of Laboratory Medicine, Yale School of Medicine, New Haven, CT, USA
- Department of Immunobiology, Yale School of Medicine, New Haven, CT, USA
| | - Anna Marie Pyle
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT, USA
- Department of Chemistry, Yale University, New Haven, CT, USA
- Howard Hughes Medical Institute, Chevy Chase, MD, USA
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6
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Kim TS, Wang L, Kim YJ, Somers DE. Compensatory Mutations in GI and ZTL May Modulate Temperature Compensation in the Circadian Clock. PLANT PHYSIOLOGY 2020; 182:1130-1141. [PMID: 31740505 PMCID: PMC6997678 DOI: 10.1104/pp.19.01120] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Accepted: 11/02/2019] [Indexed: 05/04/2023]
Abstract
Circadian systems share the three properties of entrainment, free-running period, and temperature compensation (TC). TC ensures nearly the same period over a broad range of physiologically relevant temperatures; however, the mechanisms behind TC remain poorly understood. Here, we identify single point mutations in two key elements of the Arabidopsis circadian clock, GIGANTEA (GI) and ZEITLUPE (ZTL), which likely act as compensatory substitutions to establish a remarkably constant free-running period over a wide range of temperatures. Using near-isogenic lines generated from the introgression of the Cape Verde Islands (Cvi) alleles of GI and ZTL into the Landsberg erecta (Ler) background, we show how longer periods in the Cvi background at higher temperatures correlate with a difference in strength of the GI/ZTL interaction. Pairwise interaction testing of all GI/ZTL allelic combinations shows similar affinities for isogenic alleles at 22°C, but very poor interaction between GI (Cvi) and ZTL (Cvi) at higher temperature. In vivo, this would result in lower ZTL levels at high temperatures leading to longer periods in the Cvi background. Mismatched allelic combinations result in extremely strong or weak GI/ZTL interactions, indicating how the corresponding natural variants likely became fixed through epistatic selection. Additionally, molecular characterization of GI (Cvi) reveals a novel functional motif that can modulate the GI/ZTL interaction as well as nucleocytoplasmic partitioning. Taken together, these results identify a plausible temperature-dependent molecular mechanism, which contributes to the robustness of TC through natural variation in GI and ZTL alleles found on the Cape Verde Islands.
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Affiliation(s)
- Tae-Sung Kim
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210
| | - Lei Wang
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210
| | - Yeon Jeong Kim
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210
| | - David E Somers
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210
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7
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Endless Forms: Within-Host Variation in the Structure of the West Nile Virus RNA Genome during Serial Passage in Bird Hosts. mSphere 2019; 4:4/3/e00291-19. [PMID: 31243074 PMCID: PMC6595145 DOI: 10.1128/msphere.00291-19] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The enzymes that copy RNA genomes lack proofreading, and viruses that possess RNA genomes, such as West Nile virus, rapidly diversify into swarms of mutant lineages within a host. Intrahost variation of the primary genomic sequence of RNA viruses has been studied extensively because the extent of this variation shapes key virus phenotypes. However, RNA genomes also form complex secondary structures based on within-genome nucleotide complementarity, which are critical regulators of the cyclization of the virus genome that is necessary for efficient replication and translation. We sought to characterize variation in these secondary structures within populations of West Nile virus during serial passage in three bird species. Our study indicates that the intrahost population of West Nile virus is a diverse assortment of RNA secondary structures that should be considered in future analyses of intrahost viral diversity, but some regions that are critical for genome cyclization are conserved within hosts. Besides potential impacts on viral replication, structural diversity can influence the efficacy of small RNA antiviral therapies. RNA viruses are infamous for their high rates of mutation, which produce swarms of genetic variants within individual hosts. To date, analyses of intrahost genetic diversity have focused on the primary genome sequence. However, virus phenotypes are shaped not only by primary sequence but also by the secondary structures into which this sequence folds. Such structures enable viral replication, translation, and binding of small RNAs, yet within-host variation at the structural level has not been adequately explored. We characterized the structural diversity of the 5′ untranslated region (UTR) of populations of West Nile virus (WNV) that had been subject to five serial passages in triplicate in each of three bird species. Viral genomes were sampled from host serum samples at each passage (n = 45 populations) and subjected to next-generation sequencing. For populations derived from passages 1, 3, and 5 (n = 9 populations), we predicted the impact of each mutation occurring at a frequency of ≥1% on the secondary structure of the 5′ UTR. As expected, mutations in double-stranded (DS) regions of the 5′ UTR stem structures caused structural changes of significantly greater magnitude than did mutations in single-stranded (SS) regions. Despite the greater impact of mutations in DS regions, mutations in DS and SS regions occurred at similar frequencies, with no evidence of enhanced selection against mutation in DS regions. In contrast, mutations in two regions that mediate genome cyclization and thereby regulate replication and translation, the 5′ cyclization sequence and the UAR flanking stem (UFS), were suppressed in all three hosts. IMPORTANCE The enzymes that copy RNA genomes lack proofreading, and viruses that possess RNA genomes, such as West Nile virus, rapidly diversify into swarms of mutant lineages within a host. Intrahost variation of the primary genomic sequence of RNA viruses has been studied extensively because the extent of this variation shapes key virus phenotypes. However, RNA genomes also form complex secondary structures based on within-genome nucleotide complementarity, which are critical regulators of the cyclization of the virus genome that is necessary for efficient replication and translation. We sought to characterize variation in these secondary structures within populations of West Nile virus during serial passage in three bird species. Our study indicates that the intrahost population of West Nile virus is a diverse assortment of RNA secondary structures that should be considered in future analyses of intrahost viral diversity, but some regions that are critical for genome cyclization are conserved within hosts. Besides potential impacts on viral replication, structural diversity can influence the efficacy of small RNA antiviral therapies.
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8
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Safina KR, Mironov AA, Bazykin GA. Compensatory Evolution of Intrinsic Transcription Terminators in Bacillus Cereus. Genome Biol Evol 2018; 9:340-349. [PMID: 28201729 PMCID: PMC5381666 DOI: 10.1093/gbe/evw295] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/23/2017] [Indexed: 01/10/2023] Open
Abstract
Many RNA molecules possess complicated secondary structure critical to their function. Mutations in double-helical regions of RNA may disrupt Watson–Crick (WC) interactions causing structure destabilization or even complete loss of function. Such disruption can be compensated by another mutation restoring base pairing, as has been shown for mRNA, rRNA and tRNA. Here, we investigate the evolution of intrinsic transcription terminators between closely related strains of Bacillus cereus. While the terminator structure is maintained by strong natural selection, as evidenced by the low frequency of disrupting mutations, we observe multiple instances of pairs of disrupting-compensating mutations in RNA structure stems. Such two-step switches between different WC pairs occur very fast, consistent with the low fitness conferred by the intermediate non-WC variant. Still, they are not instantaneous, and probably involve transient fixation of the intermediate variant. The GU wobble pair is the most frequent intermediate, and remains fixed longer than other intermediates, consistent with its less disruptive effect on the RNA structure. Double switches involving non-GU intermediates are more frequent at the ends of RNA stems, probably because they are associated with smaller fitness loss. Together, these results show that the fitness landscape of bacterial transcription terminators is rather rugged, but that the fitness valleys associated with unpaired stem nucleotides are rather shallow, facilitating evolution.
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Affiliation(s)
- Ksenia R Safina
- Sector for Molecular Evolution, Institute of Information Transmission Problems (Kharkevich Institute) of the Russian Academy of Sciences, Moscow, Russia.,Department of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russia
| | - Andrey A Mironov
- Sector for Molecular Evolution, Institute of Information Transmission Problems (Kharkevich Institute) of the Russian Academy of Sciences, Moscow, Russia.,Department of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russia
| | - Georgii A Bazykin
- Sector for Molecular Evolution, Institute of Information Transmission Problems (Kharkevich Institute) of the Russian Academy of Sciences, Moscow, Russia.,Department of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russia.,Center for Data-Intensive Biomedicine and Biotechnology, Skolkovo Institute of Science and Technology, Skolkovo, Russia
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9
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Baeyens A, Naessens E, Van Nuffel A, Weening KE, Reilly AM, Claeys E, Trypsteen W, Vandekerckhove L, Eyckerman S, Gevaert K, Verhasselt B. HIV-1 Vpr N-terminal tagging affects alternative splicing of the viral genome. Sci Rep 2016; 6:34573. [PMID: 27721439 PMCID: PMC5056386 DOI: 10.1038/srep34573] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Accepted: 09/12/2016] [Indexed: 01/11/2023] Open
Abstract
To facilitate studies on Vpr function in replicating HIV-1, we aimed to tag the protein in an infectious virus. First we showed that N-, but not C-terminal HA/FLAG tagging of Vpr protein preserves Vpr cytopathicity. Cloning the tags into proviral DNA however ablated viral production and replication. By construction of additional viral variants we could show this defect was not protein- but RNA-dependent and sequence specific, and characterized by oversplicing of the genomic RNA. Simulation of genomic RNA folding suggested that introduction of the tag sequence induced an alternative folding structure in a region enriched in splice sites and splicing regulatory sequences. In silico predictions identified the HA/His6-Vpr tagging in HIV-1 to affect mRNA folding less than HA/FLAG-Vpr tagging. In vitro infectivity and mRNA splice pattern improved but did not reach wild-type values. Thus, sequence-specific insertions may interfere with mRNA splicing, possibly due to altered RNA folding. Our results point to the complexity of viral RNA genome sequence interactions. This should be taken into consideration when designing viral manipulation strategies, for both research as for biological interventions.
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Affiliation(s)
- Ann Baeyens
- Department of Clinical Chemistry, Microbiology, and Immunology, Ghent University, Ghent, Belgium
| | - Evelien Naessens
- Department of Clinical Chemistry, Microbiology, and Immunology, Ghent University, Ghent, Belgium
| | - Anouk Van Nuffel
- Department of Clinical Chemistry, Microbiology, and Immunology, Ghent University, Ghent, Belgium
| | - Karin E Weening
- Department of Clinical Chemistry, Microbiology, and Immunology, Ghent University, Ghent, Belgium
| | - Anne-Marie Reilly
- Department of Clinical Chemistry, Microbiology, and Immunology, Ghent University, Ghent, Belgium
| | - Eva Claeys
- Department of Clinical Chemistry, Microbiology, and Immunology, Ghent University, Ghent, Belgium
| | - Wim Trypsteen
- HIV Translational Research Unit, Department of Internal Medicine, Faculty of Medicine and Health Sciences, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Linos Vandekerckhove
- HIV Translational Research Unit, Department of Internal Medicine, Faculty of Medicine and Health Sciences, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Sven Eyckerman
- VIB Medical Biotechnology Center, B-9000 Ghent, Belgium.,Department of Biochemistry, Ghent University, B-9000 Ghent, Belgium
| | - Kris Gevaert
- VIB Medical Biotechnology Center, B-9000 Ghent, Belgium.,Department of Biochemistry, Ghent University, B-9000 Ghent, Belgium
| | - Bruno Verhasselt
- Department of Clinical Chemistry, Microbiology, and Immunology, Ghent University, Ghent, Belgium
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