1
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Dey A, Yan S, Schlick T, Laederach A. Abolished frameshifting for predicted structure-stabilizing SARS-CoV-2 mutants: implications to alternative conformations and their statistical structural analyses. RNA (NEW YORK, N.Y.) 2024; 30:1437-1450. [PMID: 39084880 PMCID: PMC11482603 DOI: 10.1261/rna.080035.124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Accepted: 07/21/2024] [Indexed: 08/02/2024]
Abstract
The SARS-CoV-2 frameshifting element (FSE) has been intensely studied and explored as a therapeutic target for coronavirus diseases, including COVID-19. Besides the intriguing virology, this small RNA is known to adopt many length-dependent conformations, as verified by multiple experimental and computational approaches. However, the role these alternative conformations play in the frameshifting mechanism and how to quantify this structural abundance has been an ongoing challenge. Here, we show by DMS and dual-luciferase functional assays that previously predicted FSE mutants (using the RAG graph theory approach) suppress structural transitions and abolish frameshifting. Furthermore, correlated mutation analysis of DMS data by three programs (DREEM, DRACO, and DANCE-MaP) reveals important differences in their estimation of specific RNA conformations, suggesting caution in the interpretation of such complex conformational landscapes. Overall, the abolished frameshifting in three different mutants confirms that all alternative conformations play a role in the pathways of ribosomal transition.
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Affiliation(s)
- Abhishek Dey
- Department of Biotechnology, National Institute of Pharmaceutical Education and Research (NIPER-R)-Raebareli, Lucknow 226002, India
| | - Shuting Yan
- Department of Chemistry, New York University, New York, New York 10003, USA
| | - Tamar Schlick
- Department of Chemistry, New York University, New York, New York 10003, USA
- Courant Institute of Mathematical Sciences, New York University, New York, New York 10012, USA
- NYU-ECNU Center for Computational Chemistry, NYU Shanghai, Shanghai 200062, P.R. China
- NYU Simons Center for Computational Physical Chemistry, New York University, New York, New York 10003, USA
| | - Alain Laederach
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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2
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Linzer JT, Aminov E, Abdullah AS, Kirkup CE, Diaz Ventura RI, Bijoor VR, Jung J, Huang S, Tse CG, Álvarez Toucet E, Onghai HP, Ghosh AP, Grodzki AC, Haines ER, Iyer AS, Khalil MK, Leong AP, Neuhaus MA, Park J, Shahid A, Xie M, Ziembicki JM, Simmerling C, Nagan MC. Accurately Modeling RNA Stem-Loops in an Implicit Solvent Environment. J Chem Inf Model 2024; 64:6092-6104. [PMID: 39002142 DOI: 10.1021/acs.jcim.4c00756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/15/2024]
Abstract
Ribonucleic acid (RNA) molecules can adopt a variety of secondary and tertiary structures in solution, with stem-loops being one of the more common motifs. Here, we present a systematic analysis of 15 RNA stem-loop sequences simulated with molecular dynamics simulations in an implicit solvent environment. Analysis of RNA cluster ensembles showed that the stem-loop structures can generally adopt the A-form RNA in the stem region. Loop structures are more sensitive, and experimental structures could only be reproduced with modification of CH···O interactions in the force field, combined with an implicit solvent nonpolar correction to better model base stacking interactions. Accurately modeling RNA with current atomistic physics-based models remains challenging, but the RNA systems studied herein may provide a useful benchmark set for testing other RNA modeling methods in the future.
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Affiliation(s)
- Jason T Linzer
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
| | - Ethan Aminov
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
| | - Aalim S Abdullah
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
| | - Colleen E Kirkup
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
| | - Rebeca I Diaz Ventura
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
| | - Vinay R Bijoor
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
| | - Jiyun Jung
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
| | - Sophie Huang
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
| | - Chi Gee Tse
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
| | - Emily Álvarez Toucet
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
| | - Hugo P Onghai
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
| | - Arghya P Ghosh
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
| | - Alex C Grodzki
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
| | - Emilee R Haines
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
| | - Aditya S Iyer
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
| | - Mark K Khalil
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
| | - Alexander P Leong
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
| | - Michael A Neuhaus
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
| | - Joseph Park
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
| | - Asir Shahid
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
| | - Matthew Xie
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
| | - Jan M Ziembicki
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
| | - Carlos Simmerling
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
- Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, New York 11794, United States
| | - Maria C Nagan
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
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3
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Dey A, Yan S, Schlick T, Laederach A. Abolished frameshifting for predicted structure-stabilizing SARS-CoV-2 mutants: Implications to alternative conformations and their statistical structural analyses. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.28.586935. [PMID: 38585719 PMCID: PMC10996636 DOI: 10.1101/2024.03.28.586935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
The SARS-CoV-2 frameshifting element (FSE) has been intensely studied and explored as a therapeutic target for coronavirus diseases including COVID-19. Besides the intriguing virology, this small RNA is known to adopt many length-dependent conformations, as verified by multiple experimental and computational approaches. However, the role these alternative conformations play in the frameshifting mechanism and how to quantify this structural abundance has been an ongoing challenge. Here, we show by DMS and dual-luciferase functional assays that previously predicted FSE mutants (using the RAG graph theory approach) suppress structural transitions and abolish frameshifting. Furthermore, correlated mutation analysis of DMS data by three programs (DREEM, DRACO, and DANCE-MaP) reveals important differences in their estimation of specific RNA conformations, suggesting caution in the interpretation of such complex conformational landscapes. Overall, the abolished frameshifting in three different mutants confirms that all alternative conformations play a role in the pathways of ribosomal transition.
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4
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Rolband L, Beasock D, Wang Y, Shu YG, Dinman JD, Schlick T, Zhou Y, Kieft JS, Chen SJ, Bussi G, Oukhaled A, Gao X, Šulc P, Binzel D, Bhullar AS, Liang C, Guo P, Afonin KA. Biomotors, viral assembly, and RNA nanobiotechnology: Current achievements and future directions. Comput Struct Biotechnol J 2022; 20:6120-6137. [PMID: 36420155 PMCID: PMC9672130 DOI: 10.1016/j.csbj.2022.11.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 11/04/2022] [Accepted: 11/04/2022] [Indexed: 11/13/2022] Open
Abstract
The International Society of RNA Nanotechnology and Nanomedicine (ISRNN) serves to further the development of a wide variety of functional nucleic acids and other related nanotechnology platforms. To aid in the dissemination of the most recent advancements, a biennial discussion focused on biomotors, viral assembly, and RNA nanobiotechnology has been established where international experts in interdisciplinary fields such as structural biology, biophysical chemistry, nanotechnology, cell and cancer biology, and pharmacology share their latest accomplishments and future perspectives. The results summarized here highlight advancements in our understanding of viral biology and the structure-function relationship of frame-shifting elements in genomic viral RNA, improvements in the predictions of SHAPE analysis of 3D RNA structures, and the understanding of dynamic RNA structures through a variety of experimental and computational means. Additionally, recent advances in the drug delivery, vaccine design, nanopore technologies, biomotor and biomachine development, DNA packaging, RNA nanotechnology, and drug delivery are included in this critical review. We emphasize some of the novel accomplishments, major discussion topics, and present current challenges and perspectives of these emerging fields.
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Affiliation(s)
- Lewis Rolband
- University of North Carolina at Charlotte, Charlotte, NC 28223, USA
| | - Damian Beasock
- University of North Carolina at Charlotte, Charlotte, NC 28223, USA
| | - Yang Wang
- Wenzhou Institute, University of China Academy of Sciences, 1st, Jinlian Road, Longwan District, Wenzhou, Zhjiang 325001, China
| | - Yao-Gen Shu
- Wenzhou Institute, University of China Academy of Sciences, 1st, Jinlian Road, Longwan District, Wenzhou, Zhjiang 325001, China
| | | | - Tamar Schlick
- New York University, Department of Chemistry and Courant Institute of Mathematical Sciences, Simons Center for Computational Physical Chemistry, New York, NY 10012, USA
| | - Yaoqi Zhou
- Institute for Systems and Physical Biology, Shenzhen Bay Laboratory, Shenzhen, Guangdong 518107, China
| | - Jeffrey S. Kieft
- University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Shi-Jie Chen
- University of Missouri at Columbia, Columbia, MO 65211, USA
| | - Giovanni Bussi
- Scuola Internazionale Superiore di Studi Avanzati, via Bonomea 265, 34136 Trieste, Italy
| | | | - Xingfa Gao
- National Center for Nanoscience and Technology of China, Beijing 100190, China
| | - Petr Šulc
- Arizona State University, Tempe, AZ, USA
| | | | | | - Chenxi Liang
- The Ohio State University, Columbus, OH 43210, USA
| | - Peixuan Guo
- The Ohio State University, Columbus, OH 43210, USA
| | - Kirill A. Afonin
- University of North Carolina at Charlotte, Charlotte, NC 28223, USA
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5
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Benner BE, Bruce JW, Kentala JR, Murray M, Becker JT, Garcia-Miranda P, Ahlquist P, Butcher SE, Sherer NM. Perturbing HIV-1 Ribosomal Frameshifting Frequency Reveals a cis Preference for Gag-Pol Incorporation into Assembling Virions. J Virol 2022; 96:e0134921. [PMID: 34643428 PMCID: PMC8754204 DOI: 10.1128/jvi.01349-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 09/30/2021] [Indexed: 12/29/2022] Open
Abstract
HIV-1 virion production is driven by Gag and Gag-Pol (GP) proteins, with Gag forming the bulk of the capsid and driving budding, while GP binds Gag to deliver the essential virion enzymes protease, reverse transcriptase, and integrase. Virion GP levels are traditionally thought to reflect the relative abundances of GP and Gag in cells (∼1:20), dictated by the frequency of a -1 programmed ribosomal frameshifting (PRF) event occurring in gag-pol mRNAs. Here, we exploited a panel of PRF mutant viruses to show that mechanisms in addition to PRF regulate GP incorporation into virions. First, we show that GP is enriched ∼3-fold in virions relative to cells, with viral infectivity being better maintained at subphysiological levels of GP than when GP levels are too high. Second, we report that GP is more efficiently incorporated into virions when Gag and GP are synthesized in cis (i.e., from the same gag-pol mRNA) than in trans, suggesting that Gag/GP translation and assembly are spatially coupled processes. Third, we show that, surprisingly, virions exhibit a strong upper limit to trans-delivered GP incorporation; an adaptation that appears to allow the virus to temper defects to GP/Gag cleavage that may negatively impact reverse transcription. Taking these results together, we propose a "weighted Goldilocks" scenario for HIV-1 GP incorporation, wherein combined mechanisms of GP enrichment and exclusion buffer virion infectivity over a broad range of local GP concentrations. These results provide new insights into the HIV-1 virion assembly pathway relevant to the anticipated efficacy of PRF-targeted antiviral strategies. IMPORTANCE HIV-1 infectivity requires incorporation of the Gag-Pol (GP) precursor polyprotein into virions during the process of virus particle assembly. Mechanisms dictating GP incorporation into assembling virions are poorly defined, with GP levels in virions traditionally thought to solely reflect relative levels of Gag and GP expressed in cells, dictated by the frequency of a -1 programmed ribosomal frameshifting (PRF) event that occurs in gag-pol mRNAs. Herein, we provide experimental support for a "weighted Goldilocks" scenario for GP incorporation, wherein the virus exploits both random and nonrandom mechanisms to buffer infectivity over a wide range of GP expression levels. These mechanistic data are relevant to ongoing efforts to develop antiviral strategies targeting PRF frequency and/or HIV-1 virion maturation.
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Affiliation(s)
- Bayleigh E. Benner
- Department of Oncology (McArdle Laboratory for Cancer Research), Institute for Molecular Virology, and Carbone Cancer Center, University of Wisconsin—Madison, Madison, Wisconsin, USA
- UW—Madison Microbiology Doctoral Training Program, Madison, Wisconsin, USA
| | - James W. Bruce
- Department of Oncology (McArdle Laboratory for Cancer Research), Institute for Molecular Virology, and Carbone Cancer Center, University of Wisconsin—Madison, Madison, Wisconsin, USA
- John and Jeanne Rowe Center for Research in Virology, Morgridge Institute for Research, Madison, Wisconsin, USA
| | - Jacob R. Kentala
- Department of Oncology (McArdle Laboratory for Cancer Research), Institute for Molecular Virology, and Carbone Cancer Center, University of Wisconsin—Madison, Madison, Wisconsin, USA
| | - Magdalena Murray
- Department of Oncology (McArdle Laboratory for Cancer Research), Institute for Molecular Virology, and Carbone Cancer Center, University of Wisconsin—Madison, Madison, Wisconsin, USA
| | - Jordan T. Becker
- Department of Oncology (McArdle Laboratory for Cancer Research), Institute for Molecular Virology, and Carbone Cancer Center, University of Wisconsin—Madison, Madison, Wisconsin, USA
| | - Pablo Garcia-Miranda
- Department of Oncology (McArdle Laboratory for Cancer Research), Institute for Molecular Virology, and Carbone Cancer Center, University of Wisconsin—Madison, Madison, Wisconsin, USA
- Department of Biochemistry, University of Wisconsin—Madison, Madison, Wisconsin, USA
| | - Paul Ahlquist
- Department of Oncology (McArdle Laboratory for Cancer Research), Institute for Molecular Virology, and Carbone Cancer Center, University of Wisconsin—Madison, Madison, Wisconsin, USA
- John and Jeanne Rowe Center for Research in Virology, Morgridge Institute for Research, Madison, Wisconsin, USA
| | - Samuel E. Butcher
- Department of Biochemistry, University of Wisconsin—Madison, Madison, Wisconsin, USA
| | - Nathan M. Sherer
- Department of Oncology (McArdle Laboratory for Cancer Research), Institute for Molecular Virology, and Carbone Cancer Center, University of Wisconsin—Madison, Madison, Wisconsin, USA
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6
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Schlick T, Zhu Q, Dey A, Jain S, Yan S, Laederach A. To Knot or Not to Knot: Multiple Conformations of the SARS-CoV-2 Frameshifting RNA Element. J Am Chem Soc 2021; 143:11404-11422. [PMID: 34283611 PMCID: PMC8315264 DOI: 10.1021/jacs.1c03003] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The SARS-CoV-2 frameshifting RNA element (FSE) is an excellent target for therapeutic intervention against Covid-19. This small gene element employs a shifting mechanism to pause and backtrack the ribosome during translation between Open Reading Frames 1a and 1b, which code for viral polyproteins. Any interference with this process has a profound effect on viral replication and propagation. Pinpointing the structures adapted by the FSE and associated structural transformations involved in frameshifting has been a challenge. Using our graph-theory-based modeling tools for representing RNA secondary structures, "RAG" (RNA-As-Graphs), and chemical structure probing experiments, we show that the 3-stem H-type pseudoknot (3_6 dual graph), long assumed to be the dominant structure, has a viable alternative, an HL-type 3-stem pseudoknot (3_3) for longer constructs. In addition, an unknotted 3-way junction RNA (3_5) emerges as a minor conformation. These three conformations share Stems 1 and 3, while the different Stem 2 may be involved in a conformational switch and possibly associations with the ribosome during translation. For full-length genomes, a stem-loop motif (2_2) may compete with these forms. These structural and mechanistic insights advance our understanding of the SARS-CoV-2 frameshifting process and concomitant virus life cycle, and point to three avenues of therapeutic intervention.
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Affiliation(s)
- Tamar Schlick
- Department of Chemistry, New York University, 100 Washington Square East, Silver Building, New York, New York 10003, United States
- Courant Institute of Mathematical Sciences, New York University, 251 Mercer Street, New York, New York 10012, United States
- New York University-East China Normal University Center for Computational Chemistry, New York University-Shanghai, Shanghai 200062, P. R. China
| | - Qiyao Zhu
- Courant Institute of Mathematical Sciences, New York University, 251 Mercer Street, New York, New York 10012, United States
| | - Abhishek Dey
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Swati Jain
- Department of Chemistry, New York University, 100 Washington Square East, Silver Building, New York, New York 10003, United States
| | - Shuting Yan
- Department of Chemistry, New York University, 100 Washington Square East, Silver Building, New York, New York 10003, United States
| | - Alain Laederach
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
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7
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Schlick T, Zhu Q, Dey A, Jain S, Yan S, Laederach A. To knot or not to knot: Multiple conformations of the SARS-CoV-2 frameshifting RNA element. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2021:2021.03.31.437955. [PMID: 33821274 PMCID: PMC8020974 DOI: 10.1101/2021.03.31.437955] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The SARS-CoV-2 frameshifting RNA element (FSE) is an excellent target for therapeutic intervention against Covid-19. This small gene element employs a shifting mechanism to pause and backtrack the ribosome during translation between Open Reading Frames 1a and 1b, which code for viral polyproteins. Any interference with this process has profound effect on viral replication and propagation. Pinpointing the structures adapted by the FSE and associated structural transformations involved in frameshifting has been a challenge. Using our graph-theory-based modeling tools for representing RNA secondary structures, "RAG" (RNA-As-Graphs), and chemical structure probing experiments, we show that the 3-stem H-type pseudoknot (3_6 dual graph), long assumed to be the dominant structure has a viable alternative, an HL-type 3-stem pseudoknot (3_3) for longer constructs. In addition, an unknotted 3-way junction RNA (3_5) emerges as a minor conformation. These three conformations share Stems 1 and 3, while the different Stem 2 may be involved in a conformational switch and possibly associations with the ribosome during translation. For full-length genomes, a stem-loop motif (2_2) may compete with these forms. These structural and mechanistic insights advance our understanding of the SARS-CoV-2 frameshifting process and concomitant virus life cycle, and point to three avenues of therapeutic intervention.
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Affiliation(s)
- Tamar Schlick
- Department of Chemistry, 100 Washington Square East, Silver Building, New York University, New York, NY 10003 U.S.A
- Courant Institute of Mathematical Sciences, New York University, 251 Mercer St., New York, NY 10012 U.S.A
- NYU-ECNU Center for Computational Chemistry, NYU Shanghai, Shanghai 200062, P.R. China
| | - Qiyao Zhu
- Courant Institute of Mathematical Sciences, New York University, 251 Mercer St., New York, NY 10012 U.S.A
| | - Abhishek Dey
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Swati Jain
- Department of Chemistry, 100 Washington Square East, Silver Building, New York University, New York, NY 10003 U.S.A
| | - Shuting Yan
- Department of Chemistry, 100 Washington Square East, Silver Building, New York University, New York, NY 10003 U.S.A
| | - Alain Laederach
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
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8
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Yang L, Toh DFK, Krishna MS, Zhong Z, Liu Y, Wang S, Gong Y, Chen G. Tertiary Base Triple Formation in the SRV-1 Frameshifting Pseudoknot Stabilizes Secondary Structure Components. Biochemistry 2020; 59:4429-4438. [PMID: 33166472 DOI: 10.1021/acs.biochem.0c00611] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Minor-groove base triples formed between stem 1 and loop 2 of the simian retrovirus type 1 (SRV-1) mRNA frameshifting pseudoknot are essential in stimulating -1 ribosomal frameshifting. How tertiary base triple formation affects the local stabilities of secondary structures (stem 1 and stem 2) and thus ribosomal frameshifting efficiency is not well understood. We made a short peptide nucleic acid (PNA) that is expected to invade stem 1 of the SRV-1 pseudoknot by PNA-RNA duplex formation to mimic the stem 1 unwinding process by a translating ribosome. In addition, we used a PNA for invading stem 2 in the SRV-1 pseudoknot. Our nondenaturing polyacrylamide gel electrophoresis data for the binding of PNA to the SRV-1 pseudoknot and mutants reveal that mutations in loop 2 disrupting base triple formation between loop 2 and stem 1 in the SRV-1 pseudoknot result in enhanced invasion by both PNAs. Our data suggest that tertiary stem 1-loop 2 base triple interactions in the SRV-1 pseudoknot can stabilize both of the secondary structural components, stem 1 and stem 2. Stem 2 stability is thus coupled to the structural stability of stem 1-loop 2 base triples, mediated through a long-range effect. The apparent dissociation constants of both PNAs are positively correlated with the pseudoknot mechanical stabilities and frameshifting efficiencies. The relatively simple PNA local invasion experiment may be used to characterize the energetic contribution of tertiary interactions and ligand binding in many other RNA and DNA structures.
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Affiliation(s)
- Lixia Yang
- School of Life Science and Technology, University of Electronic Science and Technology of China, No. 4, Section 2, North Jianshe Road, Chengdu, Sichuan 610054, P. R. China.,School of Life and Health Sciences, The Chinese University of Hong Kong, Shenzhen (CUHK-Shenzhen), No. 2001 Longxiang Boulevard, Longgang District, Shenzhen, Guangdong 518172, P. R. China.,Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Desiree-Faye Kaixin Toh
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Manchugondanahalli S Krishna
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Zhensheng Zhong
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275, P. R. China
| | - Yiyao Liu
- School of Life Science and Technology, University of Electronic Science and Technology of China, No. 4, Section 2, North Jianshe Road, Chengdu, Sichuan 610054, P. R. China
| | - Shaomeng Wang
- School of Electronic Science and Engineering, University of Electronic Science and Technology of China, No. 4, Section 2, North Jianshe Road, Chengdu, Sichuan 610054, P. R. China
| | - Yubin Gong
- School of Electronic Science and Engineering, University of Electronic Science and Technology of China, No. 4, Section 2, North Jianshe Road, Chengdu, Sichuan 610054, P. R. China
| | - Gang Chen
- School of Life and Health Sciences, The Chinese University of Hong Kong, Shenzhen (CUHK-Shenzhen), No. 2001 Longxiang Boulevard, Longgang District, Shenzhen, Guangdong 518172, P. R. China.,Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
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9
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Mikl M, Pilpel Y, Segal E. High-throughput interrogation of programmed ribosomal frameshifting in human cells. Nat Commun 2020; 11:3061. [PMID: 32546731 PMCID: PMC7297798 DOI: 10.1038/s41467-020-16961-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 05/28/2020] [Indexed: 12/30/2022] Open
Abstract
Programmed ribosomal frameshifting (PRF) is the controlled slippage of the translating ribosome to an alternative frame. This process is widely employed by human viruses such as HIV and SARS coronavirus and is critical for their replication. Here, we developed a high-throughput approach to assess the frameshifting potential of a sequence. We designed and tested >12,000 sequences based on 15 viral and human PRF events, allowing us to systematically dissect the rules governing ribosomal frameshifting and discover novel regulatory inputs based on amino acid properties and tRNA availability. We assessed the natural variation in HIV gag-pol frameshifting rates by testing >500 clinical isolates and identified subtype-specific differences and associations between viral load in patients and the optimality of PRF rates. We devised computational models that accurately predict frameshifting potential and frameshifting rates, including subtle differences between HIV isolates. This approach can contribute to the development of antiviral agents targeting PRF.
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Affiliation(s)
- Martin Mikl
- Department of Computer Science and Applied Mathematics, Rehovot, 7610001, Israel.
- Department of Molecular Cell Biology and Weizmann Institute of Science, Rehovot, 7610001, Israel.
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, 7610001, Israel.
- Department of Human Biology, Faculty of Natural Sciences, University of Haifa, Mount Carmel, Haifa, 31905, Israel.
| | - Yitzhak Pilpel
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, 7610001, Israel
| | - Eran Segal
- Department of Computer Science and Applied Mathematics, Rehovot, 7610001, Israel.
- Department of Molecular Cell Biology and Weizmann Institute of Science, Rehovot, 7610001, Israel.
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10
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Bao C, Loerch S, Ling C, Korostelev AA, Grigorieff N, Ermolenko DN. mRNA stem-loops can pause the ribosome by hindering A-site tRNA binding. eLife 2020; 9:e55799. [PMID: 32427100 PMCID: PMC7282821 DOI: 10.7554/elife.55799] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 05/18/2020] [Indexed: 12/27/2022] Open
Abstract
Although the elongating ribosome is an efficient helicase, certain mRNA stem-loop structures are known to impede ribosome movement along mRNA and stimulate programmed ribosome frameshifting via mechanisms that are not well understood. Using biochemical and single-molecule Förster resonance energy transfer (smFRET) experiments, we studied how frameshift-inducing stem-loops from E. coli dnaX mRNA and the gag-pol transcript of Human Immunodeficiency Virus (HIV) perturb translation elongation. We find that upon encountering the ribosome, the stem-loops strongly inhibit A-site tRNA binding and ribosome intersubunit rotation that accompanies translation elongation. Electron cryo-microscopy (cryo-EM) reveals that the HIV stem-loop docks into the A site of the ribosome. Our results suggest that mRNA stem-loops can transiently escape the ribosome helicase by binding to the A site. Thus, the stem-loops can modulate gene expression by sterically hindering tRNA binding and inhibiting translation elongation.
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Affiliation(s)
- Chen Bao
- Department of Biochemistry and Biophysics at School of Medicine and Dentistry and Center for RNA Biology, University of RochesterRochesterUnited States
| | - Sarah Loerch
- Janelia Research Campus, Howard Hughes Medical InstituteAshburnUnited States
| | - Clarence Ling
- Department of Biochemistry and Biophysics at School of Medicine and Dentistry and Center for RNA Biology, University of RochesterRochesterUnited States
| | - Andrei A Korostelev
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical SchoolWorcesterUnited States
- RNA Therapeutics Institute, University of Massachusetts Medical SchoolWorcesterUnited States
| | - Nikolaus Grigorieff
- Janelia Research Campus, Howard Hughes Medical InstituteAshburnUnited States
- RNA Therapeutics Institute, University of Massachusetts Medical SchoolWorcesterUnited States
| | - Dmitri N Ermolenko
- Department of Biochemistry and Biophysics at School of Medicine and Dentistry and Center for RNA Biology, University of RochesterRochesterUnited States
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11
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Korniy N, Samatova E, Anokhina MM, Peske F, Rodnina MV. Mechanisms and biomedical implications of -1 programmed ribosome frameshifting on viral and bacterial mRNAs. FEBS Lett 2019; 593:1468-1482. [PMID: 31222875 PMCID: PMC6771820 DOI: 10.1002/1873-3468.13478] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 05/14/2019] [Accepted: 05/26/2019] [Indexed: 12/11/2022]
Abstract
Some proteins are expressed as a result of a ribosome frameshifting event that is facilitated by a slippery site and downstream secondary structure elements in the mRNA. This review summarizes recent progress in understanding mechanisms of –1 frameshifting in several viral genes, including IBV 1a/1b, HIV‐1 gag‐pol, and SFV 6K, and in Escherichia coli dnaX. The exact frameshifting route depends on the availability of aminoacyl‐tRNAs: the ribosome normally slips into the –1‐frame during tRNA translocation, but can also frameshift during decoding at condition when aminoacyl‐tRNA is in limited supply. Different frameshifting routes and additional slippery sites allow viruses to maintain a constant production of their key proteins. The emerging idea that tRNA pools are important for frameshifting provides new direction for developing antiviral therapies.
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Affiliation(s)
- Natalia Korniy
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Ekaterina Samatova
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Maria M Anokhina
- Institute of Pathology, University Hospital of Cologne, Cologne, Germany
| | - Frank Peske
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Marina V Rodnina
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
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12
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Ali AM, Atmaj J, Van Oosterwijk N, Groves MR, Dömling A. Stapled Peptides Inhibitors: A New Window for Target Drug Discovery. Comput Struct Biotechnol J 2019; 17:263-281. [PMID: 30867891 PMCID: PMC6396041 DOI: 10.1016/j.csbj.2019.01.012] [Citation(s) in RCA: 110] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Revised: 01/28/2019] [Accepted: 01/29/2019] [Indexed: 12/11/2022] Open
Abstract
Protein-protein interaction (PPI) is a hot topic in clinical research as protein networking has a major impact in human disease. Such PPIs are potential drugs targets, leading to the need to inhibit/block specific PPIs. While small molecule inhibitors have had some success and reached clinical trials, they have generally failed to address the flat and large nature of PPI surfaces. As a result, larger biologics were developed for PPI surfaces and they have successfully targeted PPIs located outside the cell. However, biologics have low bioavailability and cannot reach intracellular targets. A novel class -hydrocarbon-stapled α-helical peptides that are synthetic mini-proteins locked into their bioactive structure through site-specific introduction of a chemical linker- has shown promise. Stapled peptides show an ability to inhibit intracellular PPIs that previously have been intractable with traditional small molecule or biologics, suggesting that they offer a novel therapeutic modality. In this review, we highlight what stapling adds to natural-mimicking peptides, describe the revolution of synthetic chemistry techniques and how current drug discovery approaches have been adapted to stabilize active peptide conformations, including ring-closing metathesis (RCM), lactamisation, cycloadditions and reversible reactions. We provide an overview on the available stapled peptide high-resolution structures in the protein data bank, with four selected structures discussed in details due to remarkable interactions of their staple with the target surface. We believe that stapled peptides are promising drug candidates and open the doors for peptide therapeutics to reach currently "undruggable" space.
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Affiliation(s)
| | | | | | | | - Alexander Dömling
- Department of Drug Design, University of Groningen, Antonius Deusinglaan1, 9700AD Groningen, the Netherlands
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13
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Zhao RY. Yeast for virus research. MICROBIAL CELL (GRAZ, AUSTRIA) 2017; 4:311-330. [PMID: 29082230 PMCID: PMC5657823 DOI: 10.15698/mic2017.10.592] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 08/27/2017] [Indexed: 12/25/2022]
Abstract
Budding yeast (Saccharomyces cerevisiae) and fission yeast (Schizosaccharomyces pombe) are two popular model organisms for virus research. They are natural hosts for viruses as they carry their own indigenous viruses. Both yeasts have been used for studies of plant, animal and human viruses. Many positive sense (+) RNA viruses and some DNA viruses replicate with various levels in yeasts, thus allowing study of those viral activities during viral life cycle. Yeasts are single cell eukaryotic organisms. Hence, many of the fundamental cellular functions such as cell cycle regulation or programed cell death are highly conserved from yeasts to higher eukaryotes. Therefore, they are particularly suited to study the impact of those viral activities on related cellular activities during virus-host interactions. Yeasts present many unique advantages in virus research over high eukaryotes. Yeast cells are easy to maintain in the laboratory with relative short doubling time. They are non-biohazardous, genetically amendable with small genomes that permit genome-wide analysis of virologic and cellular functions. In this review, similarities and differences of these two yeasts are described. Studies of virologic activities such as viral translation, viral replication and genome-wide study of virus-cell interactions in yeasts are highlighted. Impacts of viral proteins on basic cellular functions such as cell cycle regulation and programed cell death are discussed. Potential applications of using yeasts as hosts to carry out functional analysis of small viral genome and to develop high throughput drug screening platform for the discovery of antiviral drugs are presented.
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Affiliation(s)
- Richard Yuqi Zhao
- Department of Pathology, Department of Microbiology and Immunology, Institute of Global Health, and Institute of Human Virology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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14
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Ritchie DB, Cappellano TR, Tittle C, Rezajooei N, Rouleau L, Sikkema WKA, Woodside MT. Conformational dynamics of the frameshift stimulatory structure in HIV-1. RNA (NEW YORK, N.Y.) 2017; 23:1376-1384. [PMID: 28522581 PMCID: PMC5558907 DOI: 10.1261/rna.061655.117] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 05/12/2017] [Indexed: 05/02/2023]
Abstract
Programmed ribosomal frameshifting (PRF) in HIV-1 is thought to be stimulated by a hairpin in the mRNA, although a pseudoknot-like triplex has also been proposed. Because the conformational dynamics of the stimulatory structure under tension applied by the ribosomal helicase during translation may play an important role in PRF, we used optical tweezers to apply tension to the HIV stimulatory structure and monitor its unfolding and refolding dynamics. The folding and unfolding kinetics and energy landscape of the hairpin were measured by ramping the force on the hairpin up and down, providing a detailed biophysical characterization. Unexpectedly, whereas unfolding reflected the simple two-state behavior typical of many hairpins, refolding was more complex, displaying significant heterogeneity. Evidence was found for multiple refolding pathways as well as previously unsuspected, partially folded intermediates. Measuring a variant mRNA containing only the sequence required to form the proposed triplex, it behaved largely in the same way. Nonetheless, very rarely, high-force unfolding events characteristic of pseudoknot-like structures were observed. The rare occurrence of the triplex suggests that the hairpin is the functional stimulatory structure. The unusual heterogeneity of the hairpin dynamics under tension suggests a possible functional role in PRF similar to the dynamics of other stimulatory structures.
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Affiliation(s)
- Dustin B Ritchie
- Department of Physics, University of Alberta, Edmonton AB T6G 2E1, Canada
| | - Tonia R Cappellano
- Department of Physics, University of Alberta, Edmonton AB T6G 2E1, Canada
| | - Collin Tittle
- Department of Physics, University of Alberta, Edmonton AB T6G 2E1, Canada
| | - Negar Rezajooei
- Department of Physics, University of Alberta, Edmonton AB T6G 2E1, Canada
| | - Logan Rouleau
- Department of Physics, University of Alberta, Edmonton AB T6G 2E1, Canada
| | | | - Michael T Woodside
- Department of Physics, University of Alberta, Edmonton AB T6G 2E1, Canada
- National Institute for Nanotechnology, National Research Council, Edmonton AB T6G 2M9, Canada
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15
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Chang AT, Tran M, Nikonowicz EP. Structure and Dynamics of the Tetra-A Loop and (A-A)-U Sequence Motif within the Coliphage GA Replicase RNA Operator. Biochemistry 2017; 56:2690-2700. [PMID: 28488852 DOI: 10.1021/acs.biochem.7b00123] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The three-dimensional structure of a RNA hairpin containing the RNA operator binding site for bacteriophage GA coat protein is presented. The phage GA operator contains the asymmetric (A-A)-U sequence motif and is capped by a four-adenine (tetra-A) loop. The uridine of the (A-A)-U motif preferentially pairs with the 5'-proximal cross-strand adenine, and the 3'-proximal adenine stacks into the helix. The tetra-A loop is well-ordered with adenine residues 2-4 forming a 3' stack. This loop conformation stands in contrast to the structure of the 5'-AUUA loop of the related phage MS2 operator in which residues 1 and 2 form a 5' stack. The context dependence of the (A-A)-U sequence motif conformation was examined using structures of 76 unique occurrences from the Protein Data Bank. The motif almost always has one adenine bulged and the other adenine adopting an A-U base pair. In the case in which the (A-A)-U motif is flanked by only one Watson-Crick base pair, the adenine adjacent to the flanking base pair tends to bulge; 80% of motifs with a 3' flanking pair have a 3' bulged adenine, and 84% of motifs with a 5' flanking pair have a 5' bulged adenine. The frequencies of 3'- and 5'-proximal adenines bulging are 33 and 67%, respectively, when the (A-A)-U motif is flanked by base pairs on both sides. Although a 3' flanking cytidine correlates (88%) with bulging of the 5'-proximal adenine, no strict dependence on flanking nucleotide identity was identified for the 5' side.
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Affiliation(s)
- Andrew T Chang
- Department of BioSciences, Rice University , Houston, Texas 77251-1892, United States
| | - Michelle Tran
- Department of BioSciences, Rice University , Houston, Texas 77251-1892, United States
| | - Edward P Nikonowicz
- Department of BioSciences, Rice University , Houston, Texas 77251-1892, United States
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16
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Ablation of Programmed -1 Ribosomal Frameshifting in Venezuelan Equine Encephalitis Virus Results in Attenuated Neuropathogenicity. J Virol 2017; 91:JVI.01766-16. [PMID: 27852852 DOI: 10.1128/jvi.01766-16] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 11/07/2016] [Indexed: 12/21/2022] Open
Abstract
The alphaviruses Venezuelan equine encephalitis virus (VEEV), eastern equine encephalitis virus (EEEV), and western equine encephalitis virus (WEEV) are arthropod-borne positive-strand RNA viruses that are capable of causing acute and fatal encephalitis in many mammals, including humans. VEEV was weaponized during the Cold War and is recognized as a select agent. Currently, there are no FDA-approved vaccines or therapeutics for these viruses. The spread of VEEV and other members of this family due to climate change-mediated vector range expansion underscores the need for research aimed at developing medical countermeasures. These viruses utilize programmed -1 ribosomal frameshifting (-1 PRF) to synthesize the viral trans-frame (TF) protein, which has previously been shown to be important for neuropathogenesis in the related Sindbis virus. Here, the alphavirus -1 PRF signals were characterized, revealing novel -1 PRF stimulatory structures. -1 PRF attenuation mildly affected the kinetics of VEEV accumulation in cultured cells but strongly inhibited its pathogenesis in an aerosol infection mouse model. Importantly, the decreased viral titers in the brains of mice infected with the mutant virus suggest that the alphavirus TF protein is important for passage through the blood-brain barrier and/or for neuroinvasiveness. These findings suggest a novel approach to the development of safe and effective live attenuated vaccines directed against VEEV and perhaps other closely related -1 PRF-utilizing viruses. IMPORTANCE Venezuelan equine encephalitis virus (VEEV) is a select agent that has been weaponized. This arthropod-borne positive-strand RNA virus causes acute and fatal encephalitis in many mammals, including humans. There is no vaccine or other approved therapeutic. VEEV and related alphaviruses utilize programmed -1 ribosomal frameshifting (-1 PRF) to synthesize the viral trans-frame (TF) protein, which is important for neuropathogenesis. -1 PRF attenuation strongly inhibited VEEV pathogenesis in mice, and viral replication analyses suggest that the TF protein is critical for neurological disease. These findings suggest a new approach to the development of safe and effective live attenuated vaccines directed against VEEV and other related viruses.
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17
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Qiao Q, Yan Y, Guo J, Du S, Zhang J, Jia R, Ren H, Qiao Y, Li Q. A review on architecture of the gag-pol ribosomal frameshifting RNA in human immunodeficiency virus: a variability survey of virus genotypes. J Biomol Struct Dyn 2016; 35:1629-1653. [PMID: 27485859 DOI: 10.1080/07391102.2016.1194231] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Programmed '-1' ribosomal frameshifting is necessary for expressing the pol gene overlapped from a gag of human immunodeficiency virus. A viral RNA structure that requires base pairing across the overlapping sequence region suggests a mechanism of regulating ribosome and helicase traffic during expression. To get precise roles of an element around the frameshift site, a review on architecture of the frameshifting RNA is performed in combination of reported information with augments of a representative set of 19 viral samples. In spite of a different length for the viral RNAs, a canonical comparison on the element sequence allocation is performed for viewing variability associations between virus genotypes. Additionally, recent and historical insights recognized in frameshifting regulation are looked back as for indel and single nucleotide polymorphism of RNA. As specially noted, structural changes at a frameshift site, the spacer sequence, and a three-helix junction element, as well as two Watson-Crick base pairs near a bulge and a C-G pair close a loop, are the most vital strategies for the virus frameshifting regulations. All of structural changes, which are dependent upon specific sequence variations, facilitate an elucidation about the RNA element conformation-dependent mechanism for frameshifting. These facts on disrupting base pair interactions also allow solving the problem of competition between ribosome and helicase on a same RNA template, common to single-stranded RNA viruses. In a broad perspective, each new insight of frameshifting regulation in the competition systems introduced by the RNA element construct changes will offer a compelling target for antiviral therapy.
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Affiliation(s)
- Qi Qiao
- a School of Pharmaceutical Sciences, Xiamen University , Fujian 361102 , P.R. China
| | - Yanhua Yan
- b Department of Bioscience , Luliang University , Shanxi 033001 , P.R. China
| | - Jinmei Guo
- c Department of Chemistry & Chemical Engineering , Luliang University , Shanxi 033001 , P.R. China
| | - Shuqiang Du
- c Department of Chemistry & Chemical Engineering , Luliang University , Shanxi 033001 , P.R. China
| | - Jiangtao Zhang
- b Department of Bioscience , Luliang University , Shanxi 033001 , P.R. China
| | - Ruyue Jia
- c Department of Chemistry & Chemical Engineering , Luliang University , Shanxi 033001 , P.R. China
| | - Haimin Ren
- c Department of Chemistry & Chemical Engineering , Luliang University , Shanxi 033001 , P.R. China
| | - Yuanbiao Qiao
- d Graduate Institute of Pharmaceutical Chemistry, Luliang University , Shanxi 033001 , P.R. China
| | - Qingshan Li
- e School of Pharmaceutical Sciences , Shanxi Medical University , Shanxi 030001 , P.R. China
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18
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Hilimire TA, Bennett RP, Stewart RA, Garcia-Miranda P, Blume A, Becker J, Sherer N, Helms ED, Butcher SE, Smith HC, Miller BL. N-Methylation as a Strategy for Enhancing the Affinity and Selectivity of RNA-binding Peptides: Application to the HIV-1 Frameshift-Stimulating RNA. ACS Chem Biol 2016; 11:88-94. [PMID: 26496521 PMCID: PMC4720131 DOI: 10.1021/acschembio.5b00682] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
![]()
Human Immunodeficiency
Virus (HIV) type 1 uses a −1 programmed
ribosomal frameshift (−1 PRF) event to translate its enzymes
from the same transcript used to encode the virus’ structural
proteins. The frequency of this event is highly regulated, and significant
deviation from the normal 5–10% frequency has been demonstrated
to decrease viral infectivity. Frameshifting is primarily regulated
by the Frameshift Stimulatory Signal RNA (FSS-RNA), a thermodynamically
stable, highly conserved stem loop that has been proposed as a therapeutic
target. We describe the design, synthesis, and testing of a series
of N-methyl peptides able to bind the HIV-1 FSS RNA
stem loop with low nanomolar affinity and high selectivity. Surface
plasmon resonance (SPR) data indicates increased affinity is a reflection
of a substantially enhanced on rate. Compounds readily penetrate cell
membranes and inhibit HIV infectivity in a pseudotyped virus assay.
Viral infectivity inhibition correlates with compound-dependent changes
in the ratios of Gag and Gag-Pol in virus particles. As the first
compounds with both single digit nanomolar affinities for the FSS
RNA and an ability to inhibit HIV in cells, these studies support
the use of N-methylation for enhancing the affinity,
selectivity, and bioactivity of RNA-binding peptides.
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Affiliation(s)
| | | | | | - Pablo Garcia-Miranda
- Department
of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706, United States
| | - Alex Blume
- Department
of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706, United States
| | - Jordan Becker
- McArdle
Laboratory for Cancer Research and Institute for Molecular Virology, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Nathan Sherer
- McArdle
Laboratory for Cancer Research and Institute for Molecular Virology, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Eric D. Helms
- Department
of Chemistry, SUNY Geneseo, Geneseo, New York 14454, United States
| | - Samuel E. Butcher
- Department
of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706, United States
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19
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Sochor F, Silvers R, Müller D, Richter C, Fürtig B, Schwalbe H. (19)F-labeling of the adenine H2-site to study large RNAs by NMR spectroscopy. JOURNAL OF BIOMOLECULAR NMR 2016; 64:63-74. [PMID: 26704707 DOI: 10.1007/s10858-015-0006-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 12/20/2015] [Indexed: 05/24/2023]
Abstract
In comparison to proteins and protein complexes, the size of RNA amenable to NMR studies is limited despite the development of new isotopic labeling strategies including deuteration and ligation of differentially labeled RNAs. Due to the restricted chemical shift dispersion in only four different nucleotides spectral resolution remains limited in larger RNAs. Labeling RNAs with the NMR-active nucleus (19)F has previously been introduced for small RNAs up to 40 nucleotides (nt). In the presented work, we study the natural occurring RNA aptamer domain of the guanine-sensing riboswitch comprising 73 nucleotides from Bacillus subtilis. The work includes protocols for improved in vitro transcription of 2-fluoroadenosine-5'-triphosphat (2F-ATP) using the mutant P266L of the T7 RNA polymerase. Our NMR analysis shows that the secondary and tertiary structure of the riboswitch is fully maintained and that the specific binding of the cognate ligand hypoxanthine is not impaired by the introduction of the (19)F isotope. The thermal stability of the (19)F-labeled riboswitch is not altered compared to the unmodified sequence, but local base pair stabilities, as measured by hydrogen exchange experiments, are modulated. The characteristic change in the chemical shift of the imino resonances detected in a (1)H,(15)N-HSQC allow the identification of Watson-Crick base paired uridine signals and the (19)F resonances can be used as reporters for tertiary and secondary structure transitions, confirming the potential of (19)F-labeling even for sizeable RNAs in the range of 70 nucleotides.
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Affiliation(s)
- F Sochor
- Institut für Organische Chemie und Chemische Biologie, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max-von-Laue-Str. 7, 60438, Frankfurt/M., Germany
| | - R Silvers
- Institut für Organische Chemie und Chemische Biologie, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max-von-Laue-Str. 7, 60438, Frankfurt/M., Germany
- Department of Chemistry, Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - D Müller
- Institut für Organische Chemie und Chemische Biologie, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max-von-Laue-Str. 7, 60438, Frankfurt/M., Germany
| | - C Richter
- Institut für Organische Chemie und Chemische Biologie, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max-von-Laue-Str. 7, 60438, Frankfurt/M., Germany
| | - B Fürtig
- Institut für Organische Chemie und Chemische Biologie, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max-von-Laue-Str. 7, 60438, Frankfurt/M., Germany.
| | - H Schwalbe
- Institut für Organische Chemie und Chemische Biologie, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max-von-Laue-Str. 7, 60438, Frankfurt/M., Germany.
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20
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Parker MS, Sallee FR, Park EA, Parker SL. Homoiterons and expansion in ribosomal RNAs. FEBS Open Bio 2015; 5:864-76. [PMID: 26636029 PMCID: PMC4637361 DOI: 10.1016/j.fob.2015.10.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 09/30/2015] [Accepted: 10/14/2015] [Indexed: 11/27/2022] Open
Abstract
Homoiterons like GGGGGGG stabilize ribosomal RNAs of thermophile prokaryotes. In eukaryotes, homoiterons are much more abundant in RNA of the larger subunit (LSU). The LSU repeats increase with phylogenetic rank to 28% entire RNA sequence in hominids. In mammal LSU RNAs, these repeats constitute 45% of the massive expansion segments. These repeats may help in anchoring of ribosomes and export of secretory proteins.
Ribosomal RNAs in both prokaryotes and eukaryotes feature numerous repeats of three or more nucleotides with the same nucleobase (homoiterons). In prokaryotes these repeats are much more frequent in thermophile compared to mesophile or psychrophile species, and have similar frequency in both large RNAs. These features point to use of prokaryotic homoiterons in stabilization of both ribosomal subunits. The two large RNAs of eukaryotic cytoplasmic ribosomes have expanded to a different degree across the evolutionary ladder. The big RNA of the larger subunit (60S LSU) evolved expansion segments of up to 2400 nucleotides, and the smaller subunit (40S SSU) RNA acquired expansion segments of not more than 700 nucleotides. In the examined eukaryotes abundance of rRNA homoiterons generally follows size and nucleotide bias of the expansion segments, and increases with GC content and especially with phylogenetic rank. Both the nucleotide bias and frequency of homoiterons are much larger in metazoan and angiosperm LSU compared to the respective SSU RNAs. This is especially pronounced in the tetrapod vertebrates and seems to culminate in the hominid mammals. The stability of secondary structure in polyribonucleotides would significantly connect to GC content, and should also relate to G and C homoiteron content. RNA modeling points to considerable presence of homoiteron-rich double-stranded segments especially in vertebrate LSU RNAs, and homoiterons with four or more nucleotides in the vertebrate and angiosperm LSU RNAs are largely confined to the expansion segments. These features could mainly relate to protein export function and attachment of LSU to endoplasmic reticulum and other subcellular networks.
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Key Words
- ES, an expansion segment
- LSU, large cytoplasmic ribosome subunit (50S in prokaryotes and archaea, 60S in eukaryotes)
- PCN, homoionic motifs with ⩾3% and ⩾50% ionic residues, found especially in Polynucleotide-binding proteins, Carrier proteins and Nuclear localization signals
- RNA expansion segment
- RNA nucleotide bias
- RNA nucleotide repeat
- SSU, small cytoplasmic ribosome subunit (30S in prokaryotes and archaea, 40S in eukaryotes)
- XN or NX, [X = a number] a nucleotide unit with same nucleobases (homoiteron), such as 4U or U4 for UUUU
- aa, amino acid residues
- mRNP, messenger ribonucleoprotein
- ncRNA, non-coding RNA
- nt, nucleotides
- u, nucleotide unit
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Affiliation(s)
- Michael S Parker
- Department of Microbiology and Molecular Cell Sciences, University of Memphis, Memphis, TN 38152, USA
| | - Floyd R Sallee
- Department of Psychiatry, University of Cincinnati School of Medicine, Cincinnati, OH 45276, USA
| | - Edwards A Park
- Department of Pharmacology, University of Tennessee Health Sciences Center, Memphis, TN 38163, USA
| | - Steven L Parker
- Department of Pharmacology, University of Tennessee Health Sciences Center, Memphis, TN 38163, USA
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21
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Mouzakis KD, Dethoff EA, Tonelli M, Al-Hashimi H, Butcher SE. Dynamic motions of the HIV-1 frameshift site RNA. Biophys J 2015; 108:644-54. [PMID: 25650931 PMCID: PMC4317556 DOI: 10.1016/j.bpj.2014.12.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Revised: 11/11/2014] [Accepted: 12/05/2014] [Indexed: 12/13/2022] Open
Abstract
The HIV-1 frameshift site (FS) plays a critical role in viral replication. During translation, the HIV-1 FS transitions from a 3-helix to a 2-helix junction RNA secondary structure. The 2-helix junction structure contains a GGA bulge, and purine-rich bulges are common motifs in RNA secondary structure. Here, we investigate the dynamics of the HIV-1 FS 2-helix junction RNA. Interhelical motions were studied under different ionic conditions using NMR order tensor analysis of residual dipolar couplings. In 150 mM potassium, the RNA adopts a 43°(±4°) interhelical bend angle (β) and displays large amplitude, anisotropic interhelical motions characterized by a 0.52(±0.04) internal generalized degree of order (GDOint) and distinct order tensor asymmetries for its two helices (η = 0.26(±0.04) and 0.5(±0.1)). These motions are effectively quenched by addition of 2 mM magnesium (GDOint = 0.87(±0.06)), which promotes a near-coaxial conformation (β = 15°(±6°)) of the two helices. Base stacking in the bulge was investigated using the fluorescent purine analog 2-aminopurine. These results indicate that magnesium stabilizes extrahelical conformations of the bulge nucleotides, thereby promoting coaxial stacking of helices. These results are highly similar to previous studies of the HIV transactivation response RNA, despite a complete lack of sequence similarity between the two RNAs. Thus, the conformational space of these RNAs is largely determined by the topology of their interhelical junctions.
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Affiliation(s)
- Kathryn D Mouzakis
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin
| | - Elizabeth A Dethoff
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina
| | - Marco Tonelli
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin
| | | | - Samuel E Butcher
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin.
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22
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Ofori LO, Hilimire TA, Bennett RP, Brown NW, Smith HC, Miller BL. High-affinity recognition of HIV-1 frameshift-stimulating RNA alters frameshifting in vitro and interferes with HIV-1 infectivity. J Med Chem 2014; 57:723-32. [PMID: 24387306 PMCID: PMC3954503 DOI: 10.1021/jm401438g] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
The
life cycle of the human immunodeficiency virus type 1 (HIV-1)
has an absolute requirement for ribosomal frameshifting during protein
translation in order to produce the polyprotein precursor of the viral
enzymes. While an RNA stem-loop structure (the “HIV-1 Frameshift
Stimulating Signal”, or HIV-1 FSS) controls the frameshift
efficiency and has been hypothesized as an attractive therapeutic
target, developing compounds that selectively bind this RNA and interfere
with HIV-1 replication has proven challenging. Building on our prior
discovery of a “hit” molecule able to bind this stem-loop,
we now report the development of compounds displaying high affinity
for the HIV-1 FSS. These compounds are able to enhance frameshifting
more than 50% in a dual-luciferase assay in human embryonic kidney
cells, and they strongly inhibit the infectivity of pseudotyped HIV-1
virions.
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Affiliation(s)
- Leslie O Ofori
- Departments of Chemistry, ‡Biochemistry and Biophysics, and §Dermatology, University of Rochester , Rochester, New York 14642, United States
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23
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van der Werf RM, Tessari M, Wijmenga SS. Nucleic acid helix structure determination from NMR proton chemical shifts. JOURNAL OF BIOMOLECULAR NMR 2013; 56:95-112. [PMID: 23564038 DOI: 10.1007/s10858-013-9725-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Accepted: 03/27/2013] [Indexed: 05/12/2023]
Abstract
We present a method for de novo derivation of the three-dimensional helix structure of nucleic acids using non-exchangeable proton chemical shifts as sole source of experimental restraints. The method is called chemical shift de novo structure derivation protocol employing singular value decomposition (CHEOPS) and uses iterative singular value decomposition to optimize the structure in helix parameter space. The correct performance of CHEOPS and its range of application are established via an extensive set of structure derivations using either simulated or experimental chemical shifts as input. The simulated input data are used to assess in a defined manner the effect of errors or limitations in the input data on the derived structures. We find that the RNA helix parameters can be determined with high accuracy. We finally demonstrate via three deposited RNA structures that experimental proton chemical shifts suffice to derive RNA helix structures with high precision and accuracy. CHEOPS provides, subject to further development, new directions for high-resolution NMR structure determination of nucleic acids.
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Affiliation(s)
- Ramon M van der Werf
- Department of Biophysical Chemistry, Institute of Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
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24
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Mouzakis KD, Lang AL, Vander Meulen KA, Easterday PD, Butcher SE. HIV-1 frameshift efficiency is primarily determined by the stability of base pairs positioned at the mRNA entrance channel of the ribosome. Nucleic Acids Res 2012; 41:1901-13. [PMID: 23248007 PMCID: PMC3561942 DOI: 10.1093/nar/gks1254] [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] [Indexed: 12/17/2022] Open
Abstract
The human immunodeficiency virus (HIV) requires a programmed −1 ribosomal frameshift for Pol gene expression. The HIV frameshift site consists of a heptanucleotide slippery sequence (UUUUUUA) followed by a spacer region and a downstream RNA stem–loop structure. Here we investigate the role of the RNA structure in promoting the −1 frameshift. The stem–loop was systematically altered to decouple the contributions of local and overall thermodynamic stability towards frameshift efficiency. No correlation between overall stability and frameshift efficiency is observed. In contrast, there is a strong correlation between frameshift efficiency and the local thermodynamic stability of the first 3–4 bp in the stem–loop, which are predicted to reside at the opening of the mRNA entrance channel when the ribosome is paused at the slippery site. Insertion or deletions in the spacer region appear to correspondingly change the identity of the base pairs encountered 8 nt downstream of the slippery site. Finally, the role of the surrounding genomic secondary structure was investigated and found to have a modest impact on frameshift efficiency, consistent with the hypothesis that the genomic secondary structure attenuates frameshifting by affecting the overall rate of translation.
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Affiliation(s)
- Kathryn D Mouzakis
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
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25
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Harjes E, Kitamura A, Zhao W, Morais MC, Jardine PJ, Grimes S, Matsuo H. Structure of the RNA claw of the DNA packaging motor of bacteriophage Φ29. Nucleic Acids Res 2012; 40:9953-63. [PMID: 22879380 PMCID: PMC3479190 DOI: 10.1093/nar/gks724] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Bacteriophage DNA packaging motors translocate their genomic DNA into viral heads, compacting it to near-crystalline density. The Bacillus subtilis phage ϕ29 has a unique ring of RNA (pRNA) that is an essential component of its motor, serving as a scaffold for the packaging ATPase. Previously, deletion of a three-base bulge (18-CCA-20) in the pRNA A-helix was shown to abolish packaging activity. Here, we solved the structure of this crucial bulge by nuclear magnetic resonance (NMR) using a 27mer RNA fragment containing the bulge (27b). The bulge actually involves five nucleotides (17-UCCA-20 and A100), as U17 and A100 are not base paired as predicted. Mutational analysis showed these newly identified bulge residues are important for DNA packaging. The bulge introduces a 33–35° bend in the helical axis, and inter-helical motion around this bend appears to be restricted. A model of the functional 120b pRNA was generated using a 27b NMR structure and the crystal structure of the 66b prohead-binding domain. Fitting this model into a cryo-EM map generated a pentameric pRNA structure; five helices projecting from the pRNA ring resemble an RNA claw. Biochemical analysis suggested that this shape is important for coordinated motor action required for DNA translocation.
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Affiliation(s)
- Elena Harjes
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
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26
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Lin Z, Gilbert RJC, Brierley I. Spacer-length dependence of programmed -1 or -2 ribosomal frameshifting on a U6A heptamer supports a role for messenger RNA (mRNA) tension in frameshifting. Nucleic Acids Res 2012; 40:8674-89. [PMID: 22743270 PMCID: PMC3458567 DOI: 10.1093/nar/gks629] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Programmed -1 ribosomal frameshifting is employed in the expression of a number of viral and cellular genes. In this process, the ribosome slips backwards by a single nucleotide and continues translation of an overlapping reading frame, generating a fusion protein. Frameshifting signals comprise a heptanucleotide slippery sequence, where the ribosome changes frame, and a stimulatory RNA structure, a stem-loop or RNA pseudoknot. Antisense oligonucleotides annealed appropriately 3' of a slippery sequence have also shown activity in frameshifting, at least in vitro. Here we examined frameshifting at the U6A slippery sequence of the HIV gag/pol signal and found high levels of both -1 and -2 frameshifting with stem-loop, pseudoknot or antisense oligonucleotide stimulators. By examining -1 and -2 frameshifting outcomes on mRNAs with varying slippery sequence-stimulatory RNA spacing distances, we found that -2 frameshifting was optimal at a spacer length 1-2 nucleotides shorter than that optimal for -1 frameshifting with all stimulatory RNAs tested. We propose that the shorter spacer increases the tension on the mRNA such that when the tRNA detaches, it more readily enters the -2 frame on the U6A heptamer. We propose that mRNA tension is central to frameshifting, whether promoted by stem-loop, pseudoknot or antisense oligonucleotide stimulator.
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Affiliation(s)
- Zhaoru Lin
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
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27
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Yeast and the AIDS virus: the odd couple. J Biomed Biotechnol 2012; 2012:549020. [PMID: 22778552 PMCID: PMC3385842 DOI: 10.1155/2012/549020] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Revised: 04/14/2012] [Accepted: 04/16/2012] [Indexed: 12/13/2022] Open
Abstract
Despite being simple eukaryotic organisms, the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe have been widely used as a model to study human pathologies and the replication of human, animal, and plant viruses, as well as the function of individual viral proteins. The complete genome of S. cerevisiae was the first of eukaryotic origin to be sequenced and contains about 6,000 genes. More than 75% of the genes have an assigned function, while more than 40% share conserved sequences with known or predicted human genes. This strong homology has allowed the function of human orthologs to be unveiled starting from the data obtained in yeast. RNA plant viruses were the first to be studied in yeast. In this paper, we focus on the use of the yeast model to study the function of the proteins of human immunodeficiency virus type 1 (HIV-1) and the search for its cellular partners. This human retrovirus is the cause of AIDS. The WHO estimates that there are 33.4 million people worldwide living with HIV/AIDS, with 2.7 million new HIV infections per year and 2.0 million annual deaths due to AIDS. Current therapy is able to control the disease but there is no permanent cure or a vaccine. By using yeast, it is possible to dissect the function of some HIV-1 proteins and discover new cellular factors common to this simple cell and humans that may become potential therapeutic targets, leading to a long-lasting treatment for AIDS.
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28
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Böckl K, Wild J, Bredl S, Kindsmüller K, Köstler J, Wagner R. Altering an artificial Gagpolnef polyprotein and mode of ENV co-administration affects the immunogenicity of a clade C HIV DNA vaccine. PLoS One 2012; 7:e34723. [PMID: 22509350 PMCID: PMC3324526 DOI: 10.1371/journal.pone.0034723] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Accepted: 03/09/2012] [Indexed: 11/19/2022] Open
Abstract
HIV-1 candidate vaccines expressing an artificial polyprotein comprising Gag, Pol and Nef (GPN) and a secreted envelope protein (Env) were shown in recent Phase I/II clinical trials to induce high levels of polyfunctional T cell responses; however, Env-specific responses clearly exceeded those against Gag. Here, we assess the impact of the GPN immunogen design and variations in the formulation and vaccination regimen of a combined GPN/Env DNA vaccine on the T cell responses against the various HIV proteins. Subtle modifications were introduced into the GPN gene to increase Gag expression, modify the expression ratio of Gag to PolNef and support budding of virus-like particles. I.m. administration of the various DNA constructs into BALB/c mice resulted in an up to 10-fold increase in Gag- and Pol-specific IFNγ(+) CD8(+) T cells compared to GPN. Co-administering Env with Gag or GPN derivatives largely abrogated Gag-specific responses. Alterations in the molar ratio of the DNA vaccines and spatially or temporally separated administration induced more balanced T cell responses. Whereas forced co-expression of Gag and Env from one plasmid induced predominantly Env-specific T cells responses, deletion of the only H-2(d) T cell epitope in Env allowed increased levels of Gag-specific T cells, suggesting competition at an epitope level. Our data demonstrate that the biochemical properties of an artificial polyprotein clearly influence the levels of antigen-specific T cells, and variations in formulation and schedule can overcome competition for the induction of these responses. These results are guiding the design of ongoing pre-clinical and clinical trials.
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MESH Headings
- Animals
- Clinical Trials, Phase III as Topic
- Female
- Gene Products, gag/biosynthesis
- Gene Products, gag/genetics
- Gene Products, gag/immunology
- HEK293 Cells
- HIV-1/genetics
- HIV-1/immunology
- Humans
- Mice
- Mice, Inbred BALB C
- Vaccines, DNA/administration & dosage
- Vaccines, DNA/immunology
- Vaccines, Synthetic/administration & dosage
- Vaccines, Synthetic/genetics
- Vaccines, Synthetic/immunology
- Vaccines, Virus-Like Particle/immunology
- env Gene Products, Human Immunodeficiency Virus/biosynthesis
- env Gene Products, Human Immunodeficiency Virus/genetics
- env Gene Products, Human Immunodeficiency Virus/immunology
- nef Gene Products, Human Immunodeficiency Virus/biosynthesis
- nef Gene Products, Human Immunodeficiency Virus/genetics
- nef Gene Products, Human Immunodeficiency Virus/immunology
- pol Gene Products, Human Immunodeficiency Virus/biosynthesis
- pol Gene Products, Human Immunodeficiency Virus/genetics
- pol Gene Products, Human Immunodeficiency Virus/immunology
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Affiliation(s)
- Katharina Böckl
- Institute of Medical Microbiology, University of Regensburg, Regensburg, Germany
| | - Jens Wild
- Institute of Medical Microbiology, University of Regensburg, Regensburg, Germany
| | - Simon Bredl
- Institute of Medical Microbiology, University of Regensburg, Regensburg, Germany
| | - Kathrin Kindsmüller
- Institute of Medical Microbiology, University of Regensburg, Regensburg, Germany
| | - Josef Köstler
- Institute of Medical Microbiology, University of Regensburg, Regensburg, Germany
| | - Ralf Wagner
- Institute of Medical Microbiology, University of Regensburg, Regensburg, Germany
- Geneart AG/Life Technologies, Regensburg, Germany
- * E-mail:
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29
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Ofori LO, Hoskins J, Nakamori M, Thornton CA, Miller BL. From dynamic combinatorial 'hit' to lead: in vitro and in vivo activity of compounds targeting the pathogenic RNAs that cause myotonic dystrophy. Nucleic Acids Res 2012; 40:6380-90. [PMID: 22492623 PMCID: PMC3401475 DOI: 10.1093/nar/gks298] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The myotonic dystrophies (DM) are human diseases in which the accumulation of toxic RNA (CUG or CCUG) repeats in the cell causes sequestration of splicing factors, including MBNL1, leading to clinical symptoms such as muscle wasting and myotonia. We previously used Dynamic Combinatorial Chemistry to identify the first compounds known to inhibit (CUG)-MBNL1 binding in vitro. We now report transformation of those compounds into structures with activity in vivo. Introduction of a benzo[g]quinoline substructure previously unknown in the context of RNA recognition, as well as other modifications, provided several molecules with enhanced binding properties, including compounds with strong selectivity for CUG repeats over CAG repeats or CAG–CUG duplex RNA. Compounds readily penetrate cells, and improve luciferase activity in a mouse myoblast assay in which enzyme function is coupled to a release of nuclear CUG–RNA retention. Most importantly, two compounds are able to partially restore splicing in a mouse model of DM1.
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Affiliation(s)
- Leslie O Ofori
- Department of Chemistry, University of Rochester, Rochester, NY 14642, USA
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30
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Bahrami A, Clos LJ, Markley JL, Butcher SE, Eghbalnia HR. RNA-PAIRS: RNA probabilistic assignment of imino resonance shifts. JOURNAL OF BIOMOLECULAR NMR 2012; 52:289-302. [PMID: 22359049 PMCID: PMC3480180 DOI: 10.1007/s10858-012-9603-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2011] [Accepted: 01/08/2012] [Indexed: 05/13/2023]
Abstract
The significant biological role of RNA has further highlighted the need for improving the accuracy, efficiency and the reach of methods for investigating RNA structure and function. Nuclear magnetic resonance (NMR) spectroscopy is vital to furthering the goals of RNA structural biology because of its distinctive capabilities. However, the dispersion pattern in the NMR spectra of RNA makes automated resonance assignment, a key step in NMR investigation of biomolecules, remarkably challenging. Herein we present RNA Probabilistic Assignment of Imino Resonance Shifts (RNA-PAIRS), a method for the automated assignment of RNA imino resonances with synchronized verification and correction of predicted secondary structure. RNA-PAIRS represents an advance in modeling the assignment paradigm because it seeds the probabilistic network for assignment with experimental NMR data, and predicted RNA secondary structure, simultaneously and from the start. Subsequently, RNA-PAIRS sets in motion a dynamic network that reverberates between predictions and experimental evidence in order to reconcile and rectify resonance assignments and secondary structure information. The procedure is halted when assignments and base-parings are deemed to be most consistent with observed crosspeaks. The current implementation of RNA-PAIRS uses an initial peak list derived from proton-nitrogen heteronuclear multiple quantum correlation ((1)H-(15)N 2D HMQC) and proton-proton nuclear Overhauser enhancement spectroscopy ((1)H-(1)H 2D NOESY) experiments. We have evaluated the performance of RNA-PAIRS by using it to analyze NMR datasets from 26 previously studied RNAs, including a 111-nucleotide complex. For moderately sized RNA molecules, and over a range of comparatively complex structural motifs, the average assignment accuracy exceeds 90%, while the average base pair prediction accuracy exceeded 93%. RNA-PAIRS yielded accurate assignments and base pairings consistent with imino resonances for a majority of the NMR resonances, even when the initial predictions are only modestly accurate. RNA-PAIRS is available as a public web-server at http://pine.nmrfam.wisc.edu/RNA/.
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Affiliation(s)
- Arash Bahrami
- National Magnetic Resonance Facility at Madison, Madison, WI, USA
| | - Lawrence J. Clos
- National Magnetic Resonance Facility at Madison, Madison, WI, USA
| | - John L. Markley
- National Magnetic Resonance Facility at Madison, Madison, WI, USA. Biochemistry Department, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Samuel E. Butcher
- National Magnetic Resonance Facility at Madison, Madison, WI, USA. Biochemistry Department, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Hamid R. Eghbalnia
- Department of Molecular and Cellular Physiology, University of Cincinnati, P.O. Box 670576, Cincinnati, OH 45267-0576, USA
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31
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Wang Z, Hartman E, Roy K, Chanfreau G, Feigon J. Structure of a yeast RNase III dsRBD complex with a noncanonical RNA substrate provides new insights into binding specificity of dsRBDs. Structure 2011; 19:999-1010. [PMID: 21742266 DOI: 10.1016/j.str.2011.03.022] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2010] [Revised: 03/01/2011] [Accepted: 03/31/2011] [Indexed: 11/15/2022]
Abstract
dsRBDs often bind dsRNAs with some specificity, yet the basis for this is poorly understood. Rnt1p, the major RNase III in Saccharomyces cerevisiae, cleaves RNA substrates containing hairpins capped by A/uGNN tetraloops, using its dsRBD to recognize a conserved tetraloop fold. However, the identification of a Rnt1p substrate with an AAGU tetraloop raised the question of whether Rnt1p binds to this noncanonical substrate differently than to A/uGNN tetraloops. The solution structure of Rnt1p dsRBD bound to an AAGU-capped hairpin reveals that the tetraloop undergoes a structural rearrangement upon binding to Rnt1p dsRBD to adopt a backbone conformation that is essentially the same as the AGAA tetraloop, and indicates that a conserved recognition mode is used for all Rnt1p substrates. Comparison of free and RNA-bound Rnt1p dsRBD reveals that tetraloop-specific binding requires a conformational change in helix α1. Our findings provide a unified model of binding site selection by this dsRBD.
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Affiliation(s)
- Zhonghua Wang
- Department of Chemistry and Biochemistry, P.O. Box 951569, University of California, Los Angeles, CA 90095-1569, USA
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32
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Marcheschi RJ, Tonelli M, Kumar A, Butcher SE. Structure of the HIV-1 frameshift site RNA bound to a small molecule inhibitor of viral replication. ACS Chem Biol 2011; 6:857-64. [PMID: 21648432 DOI: 10.1021/cb200082d] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Programmed -1 translational frameshifting is an essential event in the replication cycle of HIV. Frameshifting is required for expression of the viral Pol proteins, and drug-like molecules that target this process may inhibit HIV replication. A small molecule stimulator of HIV-1 frameshifting and inhibitor of viral replication, DB213 (RG501), was previously discovered from a high-throughput screen. However, the mechanistic basis for this compound's effects was unknown, and to date no structural information exists for small molecule effectors of frameshifting. Here, we investigate the binding of DB213 to the frameshift site RNA and have determined the structure of this complex by NMR. Binding of DB213 stabilizes the RNA and increases its melting temperature by 10 °C. The ligand binds to a primary site on the RNA stem-loop, although nonspecific interactions are also detected. The compound binds in the major groove and spans a distance of 9 base pairs. DB213 hydrogen bonds to phosphate groups on opposite sides of the major groove and alters the conformation of a conserved GGA bulge in the RNA. This study may provide a starting point for structure-based optimization of compounds targeting the HIV-1 frameshift site RNA.
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Affiliation(s)
- Ryan J. Marcheschi
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Marco Tonelli
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Arvind Kumar
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
| | - Samuel E. Butcher
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
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33
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Spano MN, Walter NG. Solution structure of an alternate conformation of helix27 from Escherichia coli16S rRNA. Biopolymers 2011; 95:653-68. [PMID: 21442607 DOI: 10.1002/bip.21626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2010] [Revised: 03/08/2011] [Accepted: 03/09/2011] [Indexed: 11/09/2022]
Abstract
Helix (H)27 of 16S ribosomal (r)RNA from Escherichia coli was dubbed the "switch helix" when mutagenesis suggested that two alternative base pair registers may have distinct functional roles in the bacterial ribosome. Although more recent genetic analyses suggest that H27 conformational switching is not required for translation, previous solution studies demonstrated that the isolated E. coli H27 can dynamically convert between the 885 and 888 conformations. Here, we have solved the nuclear magnetic resonance solution structure of a locked 888 conformation. NOE and residual dipolar coupling restraints reveal an architecture that markedly differs from that of the 885 conformation found in crystal structures of the bacterial ribosome. In place of the loop E motif that characterizes the 885 conformer and that the 888 conformer cannot adopt, we find evidence for an asymmetrical A-rich internal loop stabilized by stacking interactions among the unpaired A's. Comparison of the isolated H27 888 solution structure with the 885 crystal structure within the context of the ribosome suggests a difference in overall length of H27 that presents one plausible reason for the absence of H27 conformational switching within the sterically confining ribosome.
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34
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Abstract
Errors occur randomly and at low frequency during the translation of mRNA. However, such errors may also be programmed by the sequence and structure of the mRNA. These programmed events are called ‘recoding’ and are found mostly in viruses, in which they are usually essential for viral replication. Translational errors at a stop codon may also be induced by drugs, raising the possibility of developing new treatment protocols for genetic diseases on the basis of nonsense mutations. Many studies have been carried out, but the molecular mechanisms governing these events remain largely unknown. Studies on the yeast Saccharomyces cerevisiae have contributed to characterization of the HIV‐1 frameshifting site and have demonstrated that frameshifting is conserved from yeast to humans. Yeast has also proved a particularly useful model organism for deciphering the mechanisms of translation termination in eukaryotes and identifying the factors required to obtain a high level of natural suppression. These findings open up new possibilities for large‐scale screening in yeast to identify new drugs for blocking HIV replication by inhibiting frameshifting or restoring production of the full‐length protein from a gene inactivated by a premature termination codon. We explore these two aspects of the contribution of yeast studies to human medicine in this review.
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Affiliation(s)
- Laure Bidou
- Université Paris-Sud, IGM CNRS UMR 8621, Orsay, France
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35
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Palde PB, Ofori LO, Gareiss PC, Lerea J, Miller BL. Strategies for recognition of stem-loop RNA structures by synthetic ligands: application to the HIV-1 frameshift stimulatory sequence. J Med Chem 2010; 53:6018-27. [PMID: 20672840 DOI: 10.1021/jm100231t] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Production of the Gag-Pol polyprotein in human immunodeficiency virus (HIV) requires a -1 ribosomal frameshift, which is directed by a highly conserved RNA stem-loop. Building on our discovery of a set of disulfide-containing peptides that bind this RNA, we describe medicinal chemistry efforts designed to begin to understand the structure-activity relationships and RNA sequence-selectivity relationships associated with these compounds. Additionally, we have prepared analogues incorporating an olefin or saturated hydrocarbon bioisostere of the disulfide moiety, as a first step toward enhancing biostability. The olefin-containing compounds exhibit affinity comparable to the lead disulfide and, importantly, have no discernible toxicity when incubated with human fibroblasts at concentrations up to 1 mM.
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Affiliation(s)
- Prakash B Palde
- Department of Dermatology, University of Rochester, Rochester, NY 14642, USA
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36
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Kobayashi Y, Zhuang J, Peltz S, Dougherty J. Identification of a cellular factor that modulates HIV-1 programmed ribosomal frameshifting. J Biol Chem 2010; 285:19776-84. [PMID: 20418372 DOI: 10.1074/jbc.m109.085621] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Programmed -1 ribosomal frameshifting (PRF) is a distinctive mode of gene expression utilized by some viruses, including human immunodeficiency virus type 1 (HIV-1), to produce multiple proteins from a single mRNA. -1 PRF induces a subset of elongating ribosomes to shift their translational reading frame by 1 base in the 5' direction. The appropriate ratio of Gag to Gag-Pol synthesis is tightly regulated by the PRF signal which promotes ribosomes to shift frame, and even small changes in PRF efficiency, either up or down, have significant inhibitory effects upon virus production, making PRF essential for HIV-1 replication. Although little has been reported about the cellular factors that modulate HIV-1 PRF, the cis-acting elements regulating PRF have been extensively investigated, and the PRF signal of HIV-1 was shown to include a slippery site and frameshift stimulatory signal. Recently, a genome-wide screen performed to identify cellular factors that affect HIV-1 replication demonstrated that down-regulation of eukaryotic release factor 1 (eRF1) inhibited HIV-1 replication. Because of the eRF1 role in translation, we hypothesized that eRF1 is important for HIV-1 PRF. Using a dual luciferase reporter system harboring a HIV-1 PRF signal, results showed that depletion or inhibition of eRF1 enhanced PRF in yeast, rabbit reticulocyte lysates, and mammalian cells. Consistent with the eRF1 role in modulating HIV PRF, depleting eRF1 increased the Gag-Pol to Gag ratio in cells infected with replication-competent virus. The increase in PRF was independent of a proximal termination codon and did not result from increased ribosomal pausing at the slippery site. This is the first time that a cellular factor has been identified which can promote HIV-1 PRF and highlights HIV-1 PRF as essential for replication and an important but under exploited antiviral drug target.
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Affiliation(s)
- Yoshifumi Kobayashi
- Department of Molecular Genetics, Microbiology and Immunology, University of Medicine and Dentistry of New Jersey Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA
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37
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Hong HS, Kim YG, Hohng SC. Single-Molecule FRET Studies on Frameshifting RNA Structures of Human Immunodeficiency Virus. B KOREAN CHEM SOC 2010. [DOI: 10.5012/bkcs.2010.31.04.1021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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38
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Marcheschi RJ, Mouzakis KD, Butcher SE. Selection and characterization of small molecules that bind the HIV-1 frameshift site RNA. ACS Chem Biol 2009; 4:844-54. [PMID: 19673541 DOI: 10.1021/cb900167m] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
HIV-1 requires a -1 translational frameshift to properly synthesize the viral enzymes required for replication. The frameshift mechanism is dependent upon two RNA elements, a seven-nucleotide slippery sequence (UUUUUUA) and a downstream RNA structure. Frameshifting occurs with a frequency of approximately 5%, and increasing or decreasing this frequency may result in a decrease in viral replication. Here, we report the results of a high-throughput screen designed to find small molecules that bind to the HIV-1 frameshift site RNA. Out of 34,500 compounds screened, 202 were identified as positive hits. We show that one of these compounds, doxorubicin, binds the HIV-1 RNA with low micromolar affinity (K(d) = 2.8 microM). This binding was confirmed and localized to the RNA using NMR. Further analysis revealed that this compound increased the RNA stability by approximately 5 degrees C and decreased translational frameshifting by 28% (+/-14%), as measured in vitro.
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Affiliation(s)
- Ryan J. Marcheschi
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - Kathryn D. Mouzakis
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - Samuel E. Butcher
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
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39
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Lavoie M, Abou Elela S. Yeast ribonuclease III uses a network of multiple hydrogen bonds for RNA binding and cleavage. Biochemistry 2008; 47:8514-26. [PMID: 18646867 DOI: 10.1021/bi800238u] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Members of the bacterial RNase III family recognize a variety of short structured RNAs with few common features. It is not clear how this group of enzymes supports high cleavage fidelity while maintaining a broad base of substrates. Here we show that the yeast orthologue of RNase III (Rnt1p) uses a network of 2'-OH-dependent interactions to recognize substrates with different structures. We designed a series of bipartite substrates permitting the distinction between binding and cleavage defects. Each substrate was engineered to carry a single or multiple 2'- O-methyl or 2'-fluoro ribonucleotide substitutions to prevent the formation of hydrogen bonds with a specific nucleotide or group of nucleotides. Interestingly, introduction of 2'- O-methyl ribonucleotides near the cleavage site increased the rate of catalysis, indicating that 2'-OH are not required for cleavage. Substitution of nucleotides in known Rnt1p binding site with 2'- O-methyl ribonucleotides inhibited cleavage while single 2'-fluoro ribonucleotide substitutions did not. This indicates that while no single 2'-OH is essential for Rnt1p cleavage, small changes in the substrate structure are not tolerated. Strikingly, several nucleotide substitutions greatly increased the substrate dissociation constant with little or no effect on the Michaelis-Menten constant or rate of catalysis. Together, the results indicate that Rnt1p uses a network of nucleotide interactions to identify its substrate and support two distinct modes of binding. One mode is primarily mediated by the dsRNA binding domain and leads to the formation of stable RNA/protein complex, while the other requires the presence of the nuclease and N-terminal domains and leads to RNA cleavage.
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Affiliation(s)
- Mathieu Lavoie
- Groupe ARN/RNA Group, Département de Microbiologie et d'Infectiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Québec, Canada
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40
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Latham MP, Hanson P, Brown DJ, Pardi A. Comparison of alignment tensors generated for native tRNA(Val) using magnetic fields and liquid crystalline media. JOURNAL OF BIOMOLECULAR NMR 2008; 40:83-94. [PMID: 18026844 PMCID: PMC2846703 DOI: 10.1007/s10858-007-9212-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2007] [Accepted: 10/24/2007] [Indexed: 05/10/2023]
Abstract
Residual dipolar couplings (RDCs) complement standard NOE distance and J-coupling torsion angle data to improve the local and global structure of biomolecules in solution. One powerful application of RDCs is for domain orientation studies, which are especially valuable for structural studies of nucleic acids, where the local structure of a double helix is readily modeled and the orientations of the helical domains can then be determined from RDC data. However, RDCs obtained from only one alignment media generally result in degenerate solutions for the orientation of multiple domains. In protein systems, different alignment media are typically used to eliminate this orientational degeneracy, where the combination of RDCs from two (or more) independent alignment tensors can be used to overcome this degeneracy. It is demonstrated here for native E. coli tRNA(Val) that many of the commonly used liquid crystalline alignment media result in very similar alignment tensors, which do not eliminate the 4-fold degeneracy for orienting the two helical domains in tRNA. The intrinsic magnetic susceptibility anisotropy (MSA) of the nucleobases in tRNA(Val) was also used to obtain RDCs for magnetic alignment at 800 and 900 MHz. While these RDCs yield a different alignment tensor, the specific orientation of this tensor combined with the high rhombicity for the tensors in the liquid crystalline media only eliminates two of the four degenerate orientations for tRNA(Val). Simulations are used to show that, in optimal cases, the combination of RDCs obtained from liquid crystalline medium and MSA-induced alignment can be used to obtain a unique orientation for the two helical domains in tRNA(Val).
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41
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Staple DW, Venditti V, Niccolai N, Elson-Schwab L, Tor Y, Butcher SE. Guanidinoneomycin B recognition of an HIV-1 RNA helix. Chembiochem 2008; 9:93-102. [PMID: 18058789 PMCID: PMC2782590 DOI: 10.1002/cbic.200700251] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2007] [Indexed: 01/16/2023]
Abstract
Aminoglycoside antibiotics are small-molecule drugs that bind RNA. The affinity and specificity of aminoglycoside binding to RNA can be increased through chemical modification, such as guanidinylation. Here, we report the binding of guanidinoneomycin B (GNB) to an RNA helix from the HIV-1 frameshift site. The binding of GNB increases the melting temperature (T(m)) of the frameshift-site RNA by at least 10 degrees C, to a point at which a melting transition is not even observed in 2 M urea. A structure of the complex was obtained by using multidimensional heteronuclear NMR spectroscopic methods. We also used a novel paramagnetic-probe assay to identify the site of GNB binding to the surface of the RNA. GNB makes major-groove contacts to two sets of Watson-Crick bases and is in van der Waals contact with a highly structured ACAA tetraloop. Rings I and II of GNB fit into the major groove and form the binding interface with the RNA, whereas rings III and IV are exposed to the solvent and disordered. The binding of GNB causes a broadening of the major groove across the binding site.
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Affiliation(s)
- David W. Staple
- Department of Biochemistry, University of Wisconsin-Madison, 433 Babcock Drive, Madison, WI 53706 (USA)
| | - Vincenzo Venditti
- Biomolecular Structure Research Center and Dipartimento di Biologia Molecolare, Università di Siena, 53100 Siena (Italy)
| | - Neri Niccolai
- Biomolecular Structure Research Center and Dipartimento di Biologia Molecolare, Università di Siena, 53100 Siena (Italy)
| | - Lev Elson-Schwab
- Department of Chemistry and Biochemistry, University of California-San Diego, La Jolla, CA 92093 (USA)
| | - Yitzhak Tor
- Department of Chemistry and Biochemistry, University of California-San Diego, La Jolla, CA 92093 (USA)
| | - Samuel E. Butcher
- Department of Biochemistry, University of Wisconsin-Madison, 433 Babcock Drive, Madison, WI 53706 (USA)
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42
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Venditti V, Niccolai N, Butcher SE. Measuring the dynamic surface accessibility of RNA with the small paramagnetic molecule TEMPOL. Nucleic Acids Res 2007; 36:e20. [PMID: 18056080 PMCID: PMC2275091 DOI: 10.1093/nar/gkm1062] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The surface accessibility of macromolecules plays a key role in modulating molecular recognition events. RNA is a complex and dynamic molecule involved in many aspects of gene expression. However, there are few experimental methods available to measure the accessible surface of RNA. Here, we investigate the accessible surface of RNA using NMR and the small paramagnetic molecule TEMPOL. We investigated two RNAs with known structures, one that is extremely stable and one that is dynamic. For helical regions, the TEMPOL probing data correlate well with the predicted RNA surface, and the method is able to distinguish subtle variations in atom depths, such as the relative accessibility of pyrimidine versus purine aromatic carbon atoms. Dynamic motions are also detected by TEMPOL probing, and the method accurately reports a previously characterized pH-dependent conformational transition involving formation of a protonated C-A pair and base flipping. Some loop regions are observed to exhibit anomalously high accessibility, reflective of motions that are not evident within the ensemble of NMR structures. We conclude that TEMPOL probing can provide valuable insights into the surface accessibility and dynamics of RNA, and can also be used as an independent means of validating RNA structure and dynamics in solution.
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Affiliation(s)
- Vincenzo Venditti
- Biomolecular Structure Research Center and Dipartimento di Biologia Molecolare, Università di Siena, via Fiorentina 1, 53100 Siena, Italy
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43
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Marcheschi RJ, Staple DW, Butcher SE. Programmed ribosomal frameshifting in SIV is induced by a highly structured RNA stem-loop. J Mol Biol 2007; 373:652-63. [PMID: 17868691 PMCID: PMC2080864 DOI: 10.1016/j.jmb.2007.08.033] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2007] [Revised: 08/06/2007] [Accepted: 08/07/2007] [Indexed: 11/23/2022]
Abstract
Simian immunodeficiency virus (SIV), like its human homologues (HIV-1, HIV-2), requires a -1 translational frameshift event to properly synthesize all of the proteins required for viral replication. The frameshift mechanism is dependent upon a seven-nucleotide slippery sequence and a downstream RNA structure. In SIV, the downstream RNA structure has been proposed to be either a stem-loop or a pseudoknot. Here, we report the functional, structural and thermodynamic characterization of the SIV frameshift site RNA. Translational frameshift assays indicate that a stem-loop structure is sufficient to promote efficient frameshifting in vitro. NMR and thermodynamic studies of SIV RNA constructs of varying length further support the absence of any pseudoknot interaction and indicate the presence of a stable stem-loop structure. We determined the structure of the SIV frameshift-inducing RNA by NMR. The structure reveals a highly ordered 12 nucleotide loop containing a sheared G-A pair, cross-strand adenine stacking, two G-C base-pairs, and a novel CCC triloop turn. The loop structure and its high thermostability preclude pseudoknot formation. Sequence conservation and modeling studies suggest that HIV-2 RNA forms the same structure. We conclude that, like the main sub-groups of HIV-1, SIV and HIV-2 utilize stable stem-loop structures to function as a thermodynamic barrier to translation, thereby inducing ribosomal pausing and frameshifting.
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Affiliation(s)
| | | | - Samuel E. Butcher
- Department of Biochemistry, University of Wisconsin-Madison
- Correspondence: 433 Babcock Dr. Madison, WI 53706
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44
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Girnary R, King L, Robinson L, Elston R, Brierley I. Structure-function analysis of the ribosomal frameshifting signal of two human immunodeficiency virus type 1 isolates with increased resistance to viral protease inhibitors. J Gen Virol 2007; 88:226-235. [PMID: 17170455 DOI: 10.1099/vir.0.82064-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Expression of the pol-encoded proteins of human immunodeficiency virus type 1 (HIV-1) requires a programmed -1 ribosomal frameshift at the junction of the gag and pol coding sequences. Frameshifting takes place at a heptanucleotide slippery sequence, UUUUUUA, and is enhanced by a stimulatory RNA structure located immediately downstream. In patients undergoing viral protease (PR) inhibitor therapy, a p1/p6(gag) L449F cleavage site (CS) mutation is often observed in resistant isolates and frequently generates, at the nucleotide sequence level, a homopolymeric and potentially slippery sequence (UUUUCUU to UUUUUUU). The mutation is located within the stimulatory RNA downstream of the authentic slippery sequence and could act to augment levels of pol-encoded enzymes to counteract the PR deficit. Here, RNA secondary structure probing was employed to investigate the structure of a CS-containing frameshift signal, and the effect of this mutation on ribosomal frameshift efficiency in vitro and in tissue culture cells was determined. A second mutation, a GGG insertion in the loop of the stimulatory RNA that could conceivably lead to resistance by enhancing the activity of the structure, was also tested. It was found, however, that the CS and GGG mutations had only a very modest effect on the structure and activity of the HIV-1 frameshift signal. Thus the increased resistance to viral protease inhibitors seen with HIV-1 isolates containing mutations in the frameshifting signal is unlikely to be accounted for solely by enhancement of frameshift efficiency.
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Affiliation(s)
- Roseanne Girnary
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Louise King
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Laurence Robinson
- GlaxoSmithKline R&D, Gunnels Wood Road, Stevenage, Hertfordshire SG1 2NY, UK
| | - Robert Elston
- GlaxoSmithKline R&D, Gunnels Wood Road, Stevenage, Hertfordshire SG1 2NY, UK
| | - Ian Brierley
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
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45
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Ghazal G, Elela SA. Characterization of the reactivity determinants of a novel hairpin substrate of yeast RNase III. J Mol Biol 2006; 363:332-44. [PMID: 16962133 DOI: 10.1016/j.jmb.2006.08.028] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2006] [Revised: 07/24/2006] [Accepted: 08/07/2006] [Indexed: 11/22/2022]
Abstract
RNase III enzymes form a conserved family of proteins that specifically cleave double-stranded (dsRNA). These proteins are involved in a variety of cellular functions, including the processing of many non-coding RNAs, mRNA decay, and RNA interference. Yeast RNase III (Rnt1p) selects its substrate by recognizing the structure generated by a conserved NGNN tetraloop (G2-loop). Mutations of the invariant guanosine stringently inhibit binding and cleavage of all known Rnt1p substrates. Surprisingly, we have found that the 5' end of small nucleolar RNA 48 is processed by Rnt1p in the absence of a G2-loop. Instead, biochemical and structural analyses revealed that cleavage, in this case, is directed by a hairpin capped with an AAGU tetraloop, with a preferred adenosine in the first position (A1-loop). Chemical probing indicated that A1-loops adopt a distinct structure that varies at the 3' end where Rnt1p interacts with G2-loops. Consistently, chemical footprinting and chemical interference assays indicate that Rnt1p binds to G2 and A1-loops using different sets of nucleotides. Also, cleavage and binding assays showed that the N-terminal domain of Rnt1p aids selection of A1-capped hairpins. Together, the results suggest that Rnt1p recognizes at least two distinct classes of tetraloops using flexible protein RNA interactions. This underscores the capacity of double-stranded RNA binding proteins to use several recognition motifs for substrate identification.
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Affiliation(s)
- Ghada Ghazal
- Groupe ARN/RNA Group, Département de Microbiologie et d'Infectiologie, Faculté de Médecine, Université de Sherbrooke, Sherbrooke, Québec, Canada J1H 5N4
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46
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Gaudin C, Ghazal G, Yoshizawa S, Elela SA, Fourmy D. Structure of an AAGU tetraloop and its contribution to substrate selection by yeast RNase III. J Mol Biol 2006; 363:322-31. [PMID: 16979185 DOI: 10.1016/j.jmb.2006.08.029] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2006] [Revised: 08/04/2006] [Accepted: 08/07/2006] [Indexed: 10/24/2022]
Abstract
RNase III enzymes are a highly conserved family of proteins that specifically cleave double-stranded RNA (dsRNA). These proteins are involved in a variety of cellular functions, including the processing of many non-coding RNAs, mRNA decay, and RNA interference. In yeast Rnt1p, a dsRNA-binding domain (dsRBD) recognizes its substrate by interacting with stems capped with conserved AGNN tetraloops. The enzyme uses the tetraloop to cut 14nt to 16nt away into the stem in a ruler-like mechanism. The solution structure of Rnt1p dsRBD complexed to one of its small nucleolar (sno) RNA substrate revealed non-sequence-specific contacts with the sugar-phosphate backbone in the minor groove of the AGNN fold and the two non-conserved tetraloop nucleotides. Recently, a new form of Rnt1p substrates lacking the conserved AGNN sequence but instead harboring an AAGU tetraloop was found at the 5' end of snoRNA 48 precursor. Here, we report the solution structure of this hairpin capped with an AAGU tetraloop. Some of the stacking interactions and the position of the turn in the sugar-phosphate backbone are similar to the one observed in the AGNN loop structure; however, the AAGU sequence adopts a different conformation. The most striking difference was found at the 3' end of the loop where Rnt1p interacts with AGNN substrates. The last nucleotide is extruded from the AAGU tetraloop structure in contrast to the compact AGNN fold. The AAGU hairpin structure suggests that Rnt1p recognizes substrates with different tetraloop structures, indicating that the structural repertoire specifically recognized by Rnt1p is larger than previously anticipated.
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Affiliation(s)
- Cyril Gaudin
- Laboratoire de RMN, ICSN-CNRS 1 ave de la terrasse, 91190 Gif-sur-Yvette France
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47
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Wu B, Petersen M, Girard F, Tessari M, Wijmenga SS. Prediction of molecular alignment of nucleic acids in aligned media. JOURNAL OF BIOMOLECULAR NMR 2006; 35:103-15. [PMID: 16718586 DOI: 10.1007/s10858-006-9004-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2005] [Revised: 03/04/2006] [Accepted: 03/14/2006] [Indexed: 05/09/2023]
Abstract
We demonstrate--using the data base of all deposited DNA and RNA structures aligned in Pf1-medium and RDC refined--that for nucleic acids in a Pf1-medium the electrostatic alignment tensor can be predicted reliably and accurately via a simple and fast calculation based on the gyration tensor spanned out by the phosphodiester atoms. The rhombicity is well predicted over its full range from 0 to 0.66, while the alignment tensor orientation is predicted correctly for rhombicities up to ca. 0.4, for larger rhombicities it appears to deviate somewhat more than expected based on structural noise and measurement error. This simple analytical approach is based on the Debye-Huckel approximation for the electrostatic interaction potential, valid at distances sufficiently far away from a poly-ionic charged surface, a condition naturally enforced when the charge of alignment medium and solute are of equal sign, as for nucleic acids in a Pf1-phage medium. For the usual salt strengths and nucleic acid sizes, the Debye-Huckel screening length is smaller than the nucleic acid size, but large enough for the collective of Debye-Huckel spheres to encompass the whole molecule. The molecular alignment is then purely electrostatic, but it's functional form is under these conditions similar to that for steric alignment. The proposed analytical expression allows for very fast calculation of the alignment tensor and hence RDCs from the conformation of the nucleic acid molecule. This information provides opportunities for improved structure determination of nucleic acids, including better assessment of dynamics in (multi-domain) nucleic acids and the possibility to incorporate alignment tensor prediction from shape directly into the structure calculation process. The procedures are incorporated into MATLAB scripts, which are available on request.
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Affiliation(s)
- Bin Wu
- Laboratory of Physical Chemistry-Biophysical Chemistry, Institute of Molecules and Materials, Radboud University Nijmegen, Toernooiveld 1, 6225ED, Nijmegen, The Netherlands
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48
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Brierley I, Dos Ramos FJ. Programmed ribosomal frameshifting in HIV-1 and the SARS-CoV. Virus Res 2005; 119:29-42. [PMID: 16310880 PMCID: PMC7114087 DOI: 10.1016/j.virusres.2005.10.008] [Citation(s) in RCA: 127] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2005] [Revised: 07/31/2005] [Accepted: 10/19/2005] [Indexed: 01/11/2023]
Abstract
Ribosomal frameshifting is a mechanism of gene expression used by several RNA viruses to express replicase enzymes. This article focuses on frameshifting in two human pathogens, the retrovirus human immunodeficiency virus type 1 (HIV-1) and the coronavirus responsible for severe acute respiratory syndrome (SARS). The nature of the frameshift signals of HIV-1 and the SARS–CoV will be described and the impact of this knowledge on models of frameshifting will be considered. The role of frameshifting in the replication cycle of the two pathogens and potential antiviral therapies targeting frameshifting will also be discussed.
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Affiliation(s)
- Ian Brierley
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK.
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49
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Gaudin C, Mazauric MH, Traïkia M, Guittet E, Yoshizawa S, Fourmy D. Structure of the RNA signal essential for translational frameshifting in HIV-1. J Mol Biol 2005; 349:1024-35. [PMID: 15907937 DOI: 10.1016/j.jmb.2005.04.045] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2005] [Revised: 04/15/2005] [Accepted: 04/20/2005] [Indexed: 11/18/2022]
Abstract
Many pathogenic viruses use a programmed -1 translational frameshifting mechanism to regulate synthesis of their structural and enzymatic proteins. Frameshifting is vital for viral replication. A slippery sequence bound at the ribosomal A and P sites as well as a downstream stimulatory RNA structure are essential for frameshifting. Conflicting data have been reported concerning the structure of the downstream RNA signal in human immunodeficiency virus type 1 (HIV-1). Here, the solution structure of the HIV-1 frameshifting RNA signal was solved by heteronuclear NMR spectroscopy. This structure reveals a long hairpin fold with an internal three-nucleotide bulge. The internal loop introduces a bend between the lower and upper helical regions, a structural feature often seen in frameshifting pseudoknots. The NMR structure correlates with chemical probing data. The upper stem rich in conserved G-C Watson-Crick base-pairs is highly stable, whereas the bulge region and the lower stem are more flexible.
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Affiliation(s)
- Cyril Gaudin
- Laboratoire de RMN, ICSN-CNRS 1 ave de la terrasse, 91190 Gif-sur-Yvette, France
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50
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Staple DW, Butcher SE. Solution structure and thermodynamic investigation of the HIV-1 frameshift inducing element. J Mol Biol 2005; 349:1011-23. [PMID: 15927637 DOI: 10.1016/j.jmb.2005.03.038] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2005] [Revised: 03/10/2005] [Accepted: 03/14/2005] [Indexed: 10/25/2022]
Abstract
Expression of the HIV reverse transcriptase and other essential viral enzymes requires a -1 translational frameshift. The frameshift event is induced by two highly conserved RNA elements within the HIV-1 mRNA: a UUUUUUA heptamer known as the slippery sequence, and a downstream RNA structure. Here, we report structural and thermodynamic evidence that the HIV-1 frameshift site RNA forms a stem-loop and lower helix separated by a three-purine bulge. We have determined the structure of the 45 nucleotide frameshift site RNA using multidimensional heteronuclear nuclear magnetic resonance (NMR) methods. The upper helix is highly thermostable (T(m)>90 degrees C), forming 11 Watson-Crick base-pairs capped by a stable ACAA tetraloop. The eight base-pair lower helix was found to be only moderately stable (T(m)=47 degrees C). A three-purine bulge separates the highly stable upper helix from the lower helix. Base stacking in the bulge forms a wedge, introducing a 60 degrees bend between the helices. Interestingly, this bend is similar to those seen in a number of frameshift inducing pseudoknots for which structures have been solved. The lower helix must denature to allow the ribosome access to the slippery site, but likely functions as a positioning element that enhances frameshift efficiency.
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Affiliation(s)
- David W Staple
- Department of Biochemistry, University of Wisconsin-Madison, WI 53706, USA
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