1
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Henninger JE, Young RA. An RNA-centric view of transcription and genome organization. Mol Cell 2024; 84:3627-3643. [PMID: 39366351 DOI: 10.1016/j.molcel.2024.08.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Revised: 08/13/2024] [Accepted: 08/16/2024] [Indexed: 10/06/2024]
Abstract
Foundational models of transcriptional regulation involve the assembly of protein complexes at DNA elements associated with specific genes. These assemblies, which can include transcription factors, cofactors, RNA polymerase, and various chromatin regulators, form dynamic spatial compartments that contribute to both gene regulation and local genome architecture. This DNA-protein-centric view has been modified with recent evidence that RNA molecules have important roles to play in gene regulation and genome structure. Here, we discuss evidence that gene regulation by RNA occurs at multiple levels that include assembly of transcriptional complexes and genome compartments, feedback regulation of active genes, silencing of genes, and control of protein kinases. We thus provide an RNA-centric view of transcriptional regulation that must reside alongside the more traditional DNA-protein-centric perspectives on gene regulation and genome architecture.
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Affiliation(s)
- Jonathan E Henninger
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
| | - Richard A Young
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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2
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Schynkel T, Snippenberg WV, Verniers K, Jang GM, Krogan NJ, Mestdagh P, Vandekerckhove L, Trypsteen W. Interactome of the HIV-1 proteome and human host RNA. EMBO Rep 2024; 25:4078-4090. [PMID: 39122863 PMCID: PMC11387401 DOI: 10.1038/s44319-024-00222-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 07/18/2024] [Accepted: 07/23/2024] [Indexed: 08/12/2024] Open
Abstract
The human immunodeficiency virus (HIV-1) is highly dependent on a variety of host factors. Beside proteins, host RNA molecules are reported to aid HIV-1 replication and latency maintenance. Here, we implement multiple workflows of native RNA immunoprecipitation and sequencing (nRIPseq) to determine direct host RNA interaction partners of all 18 HIV-1 (poly)proteins. We identify 1,727 HIV-1 protein - human RNA interactions in the Jurkat cell line and 1,558 interactions in SupT1 cells for a subset of proteins, and discover distinct cellular pathways that seem to be used or controlled by HIV-1 on the RNA level: Tat binds mRNAs of proteins involved in the super elongation complex (AFF1-4, Cyclin-T1). Correlation of the interaction scores (based on binding abundancy) allows identifying the highest confidence interactions, for which we perform a small-scale knockdown screen that leads to the identification of three HIV-1 protein binding RNA interactors involved in HIV-1 replication (AFF2, H4C9 and RPLP0).
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Affiliation(s)
- Tinus Schynkel
- HIV Cure Research Center, Department of Internal Medicine and Pediatrics, Ghent University and Ghent University Hospital, Ghent, 9000, Belgium
| | - Willem van Snippenberg
- HIV Cure Research Center, Department of Internal Medicine and Pediatrics, Ghent University and Ghent University Hospital, Ghent, 9000, Belgium
- OncoRNALab, Center for Medical Genetics (CMGG), Ghent University, Ghent, 9000, Belgium
| | - Kimberly Verniers
- OncoRNALab, Center for Medical Genetics (CMGG), Ghent University, Ghent, 9000, Belgium
| | - Gwendolyn M Jang
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA, 94158, USA
- Quantitative Biosciences Institute (QBI), University of California, San Francisco, CA, 94158, USA
- J. David Gladstone Institutes, San Francisco, CA, 94158, USA
| | - Nevan J Krogan
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA, 94158, USA
- Quantitative Biosciences Institute (QBI), University of California, San Francisco, CA, 94158, USA
- J. David Gladstone Institutes, San Francisco, CA, 94158, USA
| | - Pieter Mestdagh
- OncoRNALab, Center for Medical Genetics (CMGG), Ghent University, Ghent, 9000, Belgium
| | - Linos Vandekerckhove
- HIV Cure Research Center, Department of Internal Medicine and Pediatrics, Ghent University and Ghent University Hospital, Ghent, 9000, Belgium.
| | - Wim Trypsteen
- HIV Cure Research Center, Department of Internal Medicine and Pediatrics, Ghent University and Ghent University Hospital, Ghent, 9000, Belgium.
- OncoRNALab, Center for Medical Genetics (CMGG), Ghent University, Ghent, 9000, Belgium.
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3
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D'Orso I. The HIV-1 Transcriptional Program: From Initiation to Elongation Control. J Mol Biol 2024:168690. [PMID: 38936695 DOI: 10.1016/j.jmb.2024.168690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2024] [Revised: 06/20/2024] [Accepted: 06/21/2024] [Indexed: 06/29/2024]
Abstract
A large body of work in the last four decades has revealed the key pillars of HIV-1 transcription control at the initiation and elongation steps. Here, I provide a recount of this collective knowledge starting with the genomic elements (DNA and nascent TAR RNA stem-loop) and transcription factors (cellular and the viral transactivator Tat), and later transitioning to the assembly and regulation of transcription initiation and elongation complexes, and the role of chromatin structure. Compelling evidence support a core HIV-1 transcriptional program regulated by the sequential and concerted action of cellular transcription factors and Tat to promote initiation and sustain elongation, highlighting the efficiency of a small virus to take over its host to produce the high levels of transcription required for viral replication. I summarize new advances including the use of CRISPR-Cas9, genetic tools for acute factor depletion, and imaging to study transcriptional dynamics, bursting and the progression through the multiple phases of the transcriptional cycle. Finally, I describe current challenges to future major advances and discuss areas that deserve more attention to both bolster our basic knowledge of the core HIV-1 transcriptional program and open up new therapeutic opportunities.
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Affiliation(s)
- Iván D'Orso
- Department of Microbiology, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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4
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Chakraborty A, Samant D, Sarkar R, Sangeet S, Prusty S, Roy S. RNA's Dynamic Conformational Selection and Entropic Allosteric Mechanism in Controlling Cascade Protein Binding Events. J Phys Chem Lett 2024; 15:6115-6125. [PMID: 38830201 DOI: 10.1021/acs.jpclett.4c00740] [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: 06/05/2024]
Abstract
In the TAR RNA of immunodeficiency viruses, an allosteric communication exists between a distant loop and a bulge. The bulge interacts with the TAT protein vital for transactivating viral RNA, while the loop interacts with cyclin-T1, contingent on TAT binding. Through extensive atomistic and free energy simulations, we investigate TAR-TAT binding in nonpathogenic bovine immunodeficiency virus (BIV) and pathogenic human immunodeficiency virus (HIV). Thermodynamic analysis reveals enthalpically driven binding in BIV and entropically favored binding in HIV. The broader global basin in HIV is attributed to binding-induced loop fluctuation, corroborated by nuclear magnetic resonance (NMR), indicating classical entropic allostery onset. While this loop fluctuation affects the TAT binding affinity, it generates a binding-competent conformation that aids subsequent effector (cyclin-T1) binding. This study underscores how two structurally similar apo-RNA scaffolds adopt distinct conformational selection mechanisms to drive enthalpic and entropic allostery, influencing protein affinity in the signaling cascade.
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Affiliation(s)
- Amrita Chakraborty
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Kolkata, West Bengal 741246, India
| | - Dibyamanjaree Samant
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Kolkata, West Bengal 741246, India
| | - Raju Sarkar
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Kolkata, West Bengal 741246, India
| | - Satyam Sangeet
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Kolkata, West Bengal 741246, India
| | - Sangram Prusty
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Kolkata, West Bengal 741246, India
| | - Susmita Roy
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Kolkata, West Bengal 741246, India
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5
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Jin L, Zhang S, Song Z, Heng X, Chen SJ. Kinetic pathway of HIV-1 TAR cotranscriptional folding. Nucleic Acids Res 2024; 52:6066-6078. [PMID: 38738640 PMCID: PMC11162800 DOI: 10.1093/nar/gkae362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 04/09/2024] [Accepted: 04/24/2024] [Indexed: 05/14/2024] Open
Abstract
The Trans-Activator Receptor (TAR) RNA, located at the 5'-end untranslated region (5' UTR) of the human immunodeficiency virus type 1 (HIV-1), is pivotal in the virus's life cycle. As the initial functional domain, it folds during the transcription of viral mRNA. Although TAR's role in recruiting the Tat protein for trans-activation is established, the detailed kinetic mechanisms at play during early transcription, especially at points of temporary transcriptional pausing, remain elusive. Moreover, the precise physical processes of transcriptional pause and subsequent escape are not fully elucidated. This study focuses on the folding kinetics of TAR and the biological implications by integrating computer simulations of RNA folding during transcription with nuclear magnetic resonance (NMR) spectroscopy data. The findings reveal insights into the folding mechanism of a non-native intermediate that triggers transcriptional pause, along with different folding pathways leading to transcriptional pause and readthrough. The profiling of the cotranscriptional folding pathway and identification of kinetic structural intermediates reveal a novel mechanism for viral transcriptional regulation, which could pave the way for new antiviral drug designs targeting kinetic cotranscriptional folding pathways in viral RNAs.
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Affiliation(s)
- Lei Jin
- Department of Physics and Institute of Data Science and Informatics, University of Missouri, Columbia, MO 65211, USA
| | - Sicheng Zhang
- Department of Physics and Institute of Data Science and Informatics, University of Missouri, Columbia, MO 65211, USA
| | - Zhenwei Song
- Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA
| | - Xiao Heng
- Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA
| | - Shi-Jie Chen
- Department of Physics and Institute of Data Science and Informatics, University of Missouri, Columbia, MO 65211, USA
- Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA
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6
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Ward S, Childs A, Staley C, Waugh C, Watts JA, Kotowska AM, Bhosale R, Borkar AN. Integrating cryo-OrbiSIMS with computational modelling and metadynamics simulations enhances RNA structure prediction at atomic resolution. Nat Commun 2024; 15:4367. [PMID: 38777820 PMCID: PMC11111741 DOI: 10.1038/s41467-024-48694-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Accepted: 05/05/2024] [Indexed: 05/25/2024] Open
Abstract
The 3D architecture of RNAs governs their molecular interactions, chemical reactions, and biological functions. However, a large number of RNAs and their protein complexes remain poorly understood due to the limitations of conventional structural biology techniques in deciphering their complex structures and dynamic interactions. To address this limitation, we have benchmarked an integrated approach that combines cryogenic OrbiSIMS, a state-of-the-art solid-state mass spectrometry technique, with computational methods for modelling RNA structures at atomic resolution with enhanced precision. Furthermore, using 7SK RNP as a test case, we have successfully determined the full 3D structure of a native RNA in its apo, native and disease-remodelled states, which offers insights into the structural interactions and plasticity of the 7SK complex within these states. Overall, our study establishes cryo-OrbiSIMS as a valuable tool in the field of RNA structural biology as it enables the study of challenging, native RNA systems.
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Affiliation(s)
- Shannon Ward
- School of Veterinary Medicine and Science, University of Nottingham, Nottingham, LE12 5RD, UK
- Wolfson Centre for Global Virus Research, University of Nottingham, Nottingham, LE12 5RD, UK
| | - Alex Childs
- School of Veterinary Medicine and Science, University of Nottingham, Nottingham, LE12 5RD, UK
- Wolfson Centre for Global Virus Research, University of Nottingham, Nottingham, LE12 5RD, UK
| | - Ceri Staley
- School of Veterinary Medicine and Science, University of Nottingham, Nottingham, LE12 5RD, UK
| | - Christopher Waugh
- School of Veterinary Medicine and Science, University of Nottingham, Nottingham, LE12 5RD, UK
- Wolfson Centre for Global Virus Research, University of Nottingham, Nottingham, LE12 5RD, UK
- RHy-X Limited, London, WC2A 2JR, UK
| | - Julie A Watts
- School of Pharmacy, University of Nottingham, Nottingham, NG7 2RD, UK
| | - Anna M Kotowska
- School of Pharmacy, University of Nottingham, Nottingham, NG7 2RD, UK
| | - Rahul Bhosale
- School of Biosciences, University of Nottingham, Nottingham, LE12 5RD, UK
| | - Aditi N Borkar
- School of Veterinary Medicine and Science, University of Nottingham, Nottingham, LE12 5RD, UK.
- Wolfson Centre for Global Virus Research, University of Nottingham, Nottingham, LE12 5RD, UK.
- RHy-X Limited, London, WC2A 2JR, UK.
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7
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Mbonye U, Karn J. The cell biology of HIV-1 latency and rebound. Retrovirology 2024; 21:6. [PMID: 38580979 PMCID: PMC10996279 DOI: 10.1186/s12977-024-00639-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/07/2024] Open
Abstract
Transcriptionally latent forms of replication-competent proviruses, present primarily in a small subset of memory CD4+ T cells, pose the primary barrier to a cure for HIV-1 infection because they are the source of the viral rebound that almost inevitably follows the interruption of antiretroviral therapy. Over the last 30 years, many of the factors essential for initiating HIV-1 transcription have been identified in studies performed using transformed cell lines, such as the Jurkat T-cell model. However, as highlighted in this review, several poorly understood mechanisms still need to be elucidated, including the molecular basis for promoter-proximal pausing of the transcribing complex and the detailed mechanism of the delivery of P-TEFb from 7SK snRNP. Furthermore, the central paradox of HIV-1 transcription remains unsolved: how are the initial rounds of transcription achieved in the absence of Tat? A critical limitation of the transformed cell models is that they do not recapitulate the transitions between active effector cells and quiescent memory T cells. Therefore, investigation of the molecular mechanisms of HIV-1 latency reversal and LRA efficacy in a proper physiological context requires the utilization of primary cell models. Recent mechanistic studies of HIV-1 transcription using latently infected cells recovered from donors and ex vivo cellular models of viral latency have demonstrated that the primary blocks to HIV-1 transcription in memory CD4+ T cells are restrictive epigenetic features at the proviral promoter, the cytoplasmic sequestration of key transcription initiation factors such as NFAT and NF-κB, and the vanishingly low expression of the cellular transcription elongation factor P-TEFb. One of the foremost schemes to eliminate the residual reservoir is to deliberately reactivate latent HIV-1 proviruses to enable clearance of persisting latently infected cells-the "Shock and Kill" strategy. For "Shock and Kill" to become efficient, effective, non-toxic latency-reversing agents (LRAs) must be discovered. Since multiple restrictions limit viral reactivation in primary cells, understanding the T-cell signaling mechanisms that are essential for stimulating P-TEFb biogenesis, initiation factor activation, and reversing the proviral epigenetic restrictions have become a prerequisite for the development of more effective LRAs.
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Affiliation(s)
- Uri Mbonye
- Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA.
| | - Jonathan Karn
- Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA.
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8
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Li Y, Liu X, Fujinaga K, Gross JD, Frankel AD. Enhanced NF-κB activation via HIV-1 Tat-TRAF6 cross-talk. SCIENCE ADVANCES 2024; 10:eadi4162. [PMID: 38241362 PMCID: PMC10798561 DOI: 10.1126/sciadv.adi4162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Accepted: 12/21/2023] [Indexed: 01/21/2024]
Abstract
The Tat proteins of HIV-1 and simian immunodeficiency virus (SIV) are essential for activating viral transcription. In addition, Tat stimulates nuclear factor κB (NF-κB) signaling pathways to regulate viral gene expression although its molecular mechanism is unclear. Here, we report that Tat directly activates NF-κB through the interaction with TRAF6, which is an essential upstream signaling molecule of the canonical NF-κB pathway. This interaction increases TRAF6 oligomerization and auto-ubiquitination, as well as the synthesis of K63-linked polyubiquitin chains to further activate the NF-κB pathway and HIV-1 transcription. Moreover, ectopic expression of TRAF6 significantly activates HIV-1 transcription, whereas TRAF6 knockdown inhibits transcription. Furthermore, Tat-mediated activation of NF-κB through TRAF6 is conserved among HIV-1, HIV-2, and SIV isolates. Our study uncovers yet another mechanism by which HIV-1 subverts host transcriptional pathways to enhance its own transcription.
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Affiliation(s)
- Yang Li
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94158, USA
| | - Xi Liu
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94158, USA
| | - Koh Fujinaga
- Department of Medicine, University of California, San Francisco, CA 94143, USA
| | - John D. Gross
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94158, USA
| | - Alan D. Frankel
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94158, USA
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9
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Abasi M, Ranjbari J, Ghanbarian H. 7SK small nuclear RNA (Rn7SK) induces apoptosis through intrinsic and extrinsic pathways in human embryonic kidney cell line. Mol Biol Rep 2024; 51:96. [PMID: 38193993 DOI: 10.1007/s11033-023-08934-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2023] [Accepted: 11/06/2023] [Indexed: 01/10/2024]
Abstract
BACKGROUND Rn7SK, a highly conserved small nuclear non-coding RNA, controls Polymerase II transcription machinery by activating of the Positive Transcriptional Elongation Factor b (P-TEFb). Apart from its role in transcriptional regulation, the potential functions of Rn7SK in cell apoptosis are poorly understood. In a previous study, we demonstrated that overexpression of 7SK induces apoptosis in HEK cells. However, it remains unclear whether 7SK-mediated apoptosis induction is exerted through the intrinsic or extrinsic pathways. METHODS AND RESULTS Rn7SK was overexpressed in HEK 293T cell line using Lipofectamine 2000 reagent to investigate its potential apoptotic functions. The overexpression of Rn7SK resulted in reduced cell viability through the induction of apoptosis, as evidenced by MTT assay and Annexin V/PI staining. Concurrently, alterations in the expression levels of key apoptosis-related genes were observed, as determined by quantitative RT-PCR. Furthermore, Rn7SK overexpression led to a decrease in cell proliferation, as assessed by colony formation assay and growth curve analysis. This reduction was associated with downregulated expression of key proliferative-related genes. Additionally, the migration and invasion capabilities of cells were significantly inhibited upon upregulation of Rn7SK, as demonstrated by transwell assays. CONCLUSIONS This study suggests the apoptotic role of 7SK through both intrinsic and extrinsic pathways, necessitating further investigation into its underlying mechanisms.
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Affiliation(s)
- Mozhgan Abasi
- Immunogenetics Research Center, Department of Tissue Engineering and Applied Cell Sciences, Faculty of Advanced Technologies in Medicine, Mazandaran University of Medical Sciences, Sari, Iran
- Molecular and Cell Biology Research Center, Mazandaran University of Medical Sciences, Sari, Iran
| | - Javad Ranjbari
- Department of Medical Biotechnology, School of Advanced Technologies in Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Hossein Ghanbarian
- Cellular and Molecular Biology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
- Department of Medical Biotechnology, School of Advanced Technologies in Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
- Urogenital Stem Cell Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
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10
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Levintov L, Vashisth H. Structural and computational studies of HIV-1 RNA. RNA Biol 2024; 21:1-32. [PMID: 38100535 PMCID: PMC10730233 DOI: 10.1080/15476286.2023.2289709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/21/2023] [Indexed: 12/17/2023] Open
Abstract
Viruses remain a global threat to animals, plants, and humans. The type 1 human immunodeficiency virus (HIV-1) is a member of the retrovirus family and carries an RNA genome, which is reverse transcribed into viral DNA and further integrated into the host-cell DNA for viral replication and proliferation. The RNA structures from the HIV-1 genome provide valuable insights into the mechanisms underlying the viral replication cycle. Moreover, these structures serve as models for designing novel therapeutic approaches. Here, we review structural data on RNA from the HIV-1 genome as well as computational studies based on these structural data. The review is organized according to the type of structured RNA element which contributes to different steps in the viral replication cycle. This is followed by an overview of the HIV-1 transactivation response element (TAR) RNA as a model system for understanding dynamics and interactions in the viral RNA systems. The review concludes with a description of computational studies, highlighting the impact of biomolecular simulations in elucidating the mechanistic details of various steps in the HIV-1's replication cycle.
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Affiliation(s)
- Lev Levintov
- Department of Chemical Engineering & Bioengineering, University of New Hampshire, Durham, USA
| | - Harish Vashisth
- Department of Chemical Engineering & Bioengineering, University of New Hampshire, Durham, USA
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11
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Khatkar P, Mensah G, Ning S, Cowen M, Kim Y, Williams A, Abulwerdi FA, Zhao Y, Zeng C, Le Grice SFJ, Kashanchi F. HIV-1 Transcription Inhibition Using Small RNA-Binding Molecules. Pharmaceuticals (Basel) 2023; 17:33. [PMID: 38256867 PMCID: PMC10819208 DOI: 10.3390/ph17010033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Revised: 12/11/2023] [Accepted: 12/19/2023] [Indexed: 01/24/2024] Open
Abstract
The HIV-1 transactivator protein Tat interacts with the transactivation response element (TAR) at the three-nucleotide UCU bulge to facilitate the recruitment of transcription elongation factor-b (P-TEFb) and induce the transcription of the integrated proviral genome. Therefore, the Tat-TAR interaction, unique to the virus, is a promising target for developing antiviral therapeutics. Currently, there are no FDA-approved drugs against HIV-1 transcription, suggesting the need to develop novel inhibitors that specifically target HIV-1 transcription. We have identified potential candidates that effectively inhibit viral transcription in myeloid and T cells without apparent toxicity. Among these candidates, two molecules showed inhibition of viral protein expression. A molecular docking and simulation approach was used to determine the binding dynamics of these small molecules on TAR RNA in the presence of the P-TEFb complex, which was further validated by a biotinylated RNA pulldown assay. Furthermore, we examined the effect of these molecules on transcription factors, including the SWI/SNF complex (BAF or PBAF), which plays an important role in chromatin remodeling near the transcription start site and hence regulates virus transcription. The top candidates showed significant viral transcription inhibition in primary cells infected with HIV-1 (98.6). Collectively, our study identified potential transcription inhibitors that can potentially complement existing cART drugs to address the current therapeutic gap in current regimens. Additionally, shifting of the TAR RNA loop towards Cyclin T1 upon molecule binding during molecular simulation studies suggested that targeting the TAR loop and Tat-binding UCU bulge together should be an essential feature of TAR-binding molecules/inhibitors to achieve complete viral transcription inhibition.
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Affiliation(s)
- Pooja Khatkar
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Manassas, VA 20110, USA; (P.K.)
| | - Gifty Mensah
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Manassas, VA 20110, USA; (P.K.)
| | - Shangbo Ning
- Institute of Biophysics and Department of Physics, Central China Normal University, Wuhan 430079, China
| | - Maria Cowen
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Manassas, VA 20110, USA; (P.K.)
| | - Yuriy Kim
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Manassas, VA 20110, USA; (P.K.)
| | - Anastasia Williams
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Manassas, VA 20110, USA; (P.K.)
| | | | - Yunjie Zhao
- Institute of Biophysics and Department of Physics, Central China Normal University, Wuhan 430079, China
| | - Chen Zeng
- Physics Department, The George Washington University, Washington, DC 20052, USA
| | | | - Fatah Kashanchi
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Manassas, VA 20110, USA; (P.K.)
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12
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Haslecker R, Pham VV, Glänzer D, Kreutz C, Dayie TK, D'Souza VM. Extending the toolbox for RNA biology with SegModTeX: a polymerase-driven method for site-specific and segmental labeling of RNA. Nat Commun 2023; 14:8422. [PMID: 38110450 PMCID: PMC10728113 DOI: 10.1038/s41467-023-44254-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 12/06/2023] [Indexed: 12/20/2023] Open
Abstract
RNA performs a wide range of functions regulated by its structure, dynamics, and often post-transcriptional modifications. While NMR is the leading method for understanding RNA structure and dynamics, it is currently limited by the inability to reduce spectral crowding by efficient segmental labeling. Furthermore, because of the challenging nature of RNA chemistry, the tools being developed to introduce site-specific modifications are increasingly complex and laborious. Here we use a previously designed Tgo DNA polymerase mutant to present SegModTeX - a versatile, one-pot, copy-and-paste approach to address these challenges. By precise, stepwise construction of a diverse set of RNA molecules, we demonstrate the technique to be superior to RNA polymerase driven and ligation methods owing to its substantially high yield, fidelity, and selectivity. We also show the technique to be useful for incorporating some fluorescent- and a wide range of other probes, which significantly extends the toolbox of RNA biology in general.
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Affiliation(s)
- Raphael Haslecker
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, 02138, USA
| | - Vincent V Pham
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, 02138, USA
| | - David Glänzer
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80/82, 6020, Innsbruck, Austria
| | - Christoph Kreutz
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80/82, 6020, Innsbruck, Austria
| | - Theodore Kwaku Dayie
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD, 20782, USA
| | - Victoria M D'Souza
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, 02138, USA.
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13
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Roy R, Geng A, Shi H, Merriman DK, Dethoff EA, Salmon L, Al-Hashimi HM. Kinetic Resolution of the Atomic 3D Structures Formed by Ground and Excited Conformational States in an RNA Dynamic Ensemble. J Am Chem Soc 2023; 145:22964-22978. [PMID: 37831584 DOI: 10.1021/jacs.3c04614] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2023]
Abstract
Knowing the 3D structures formed by the various conformations populating the RNA free-energy landscape, their relative abundance, and kinetic interconversion rates is required to obtain a quantitative and predictive understanding of how RNAs fold and function at the atomic level. While methods integrating ensemble-averaged experimental data with computational modeling are helping define the most abundant conformations in RNA ensembles, elucidating their kinetic rates of interconversion and determining the 3D structures of sparsely populated short-lived RNA excited conformational states (ESs) remains challenging. Here, we developed an approach integrating Rosetta-FARFAR RNA structure prediction with NMR residual dipolar couplings and relaxation dispersion that simultaneously determines the 3D structures formed by the ground-state (GS) and ES subensembles, their relative abundance, and kinetic rates of interconversion. The approach is demonstrated on HIV-1 TAR, whose six-nucleotide apical loop was previously shown to form a sparsely populated (∼13%) short-lived (lifetime ∼ 45 μs) ES. In the GS, the apical loop forms a broad distribution of open conformations interconverting on the pico-to-nanosecond time scale. Most residues are unpaired and preorganized to bind the Tat-superelongation protein complex. The apical loop zips up in the ES, forming a narrow distribution of closed conformations, which sequester critical residues required for protein recognition. Our work introduces an approach for determining the 3D ensemble models formed by sparsely populated RNA conformational states, provides a rare atomic view of an RNA ES, and kinetically resolves the atomic 3D structures of RNA conformational substates, interchanging on time scales spanning 6 orders of magnitude, from picoseconds to microseconds.
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Affiliation(s)
- Rohit Roy
- Center for Genomic and Computational Biology, Duke University School of Medicine, Durham, North Carolina 27710, United States
| | - Ainan Geng
- Department of Biochemistry, Duke University School of Medicine, Durham, North Carolina 27710, United States
| | - Honglue Shi
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Dawn K Merriman
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Elizabeth A Dethoff
- Department of Chemistry and Biophysics, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Loïc Salmon
- Department of Chemistry and Biophysics, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Hashim M Al-Hashimi
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, New York 10032, United States
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14
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Mathez G, Cagno V. Small Molecules Targeting Viral RNA. Int J Mol Sci 2023; 24:13500. [PMID: 37686306 PMCID: PMC10487773 DOI: 10.3390/ijms241713500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 08/25/2023] [Accepted: 08/28/2023] [Indexed: 09/10/2023] Open
Abstract
The majority of antivirals available target viral proteins; however, RNA is emerging as a new and promising antiviral target due to the presence of highly structured RNA in viral genomes fundamental for their replication cycle. Here, we discuss methods for the identification of RNA-targeting compounds, starting from the determination of RNA structures either from purified RNA or in living cells, followed by in silico screening on RNA and phenotypic assays to evaluate viral inhibition. Moreover, we review the small molecules known to target the programmed ribosomal frameshifting element of SARS-CoV-2, the internal ribosomal entry site of different viruses, and RNA elements of HIV.
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Affiliation(s)
| | - Valeria Cagno
- Institute of Microbiology, University Hospital of Lausanne, University of Lausanne, 1011 Lausanne, Switzerland
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15
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Oksuz O, Henninger JE, Warneford-Thomson R, Zheng MM, Erb H, Vancura A, Overholt KJ, Hawken SW, Banani SF, Lauman R, Reich LN, Robertson AL, Hannett NM, Lee TI, Zon LI, Bonasio R, Young RA. Transcription factors interact with RNA to regulate genes. Mol Cell 2023; 83:2449-2463.e13. [PMID: 37402367 PMCID: PMC10529847 DOI: 10.1016/j.molcel.2023.06.012] [Citation(s) in RCA: 59] [Impact Index Per Article: 59.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 03/16/2023] [Accepted: 06/06/2023] [Indexed: 07/06/2023]
Abstract
Transcription factors (TFs) orchestrate the gene expression programs that define each cell's identity. The canonical TF accomplishes this with two domains, one that binds specific DNA sequences and the other that binds protein coactivators or corepressors. We find that at least half of TFs also bind RNA, doing so through a previously unrecognized domain with sequence and functional features analogous to the arginine-rich motif of the HIV transcriptional activator Tat. RNA binding contributes to TF function by promoting the dynamic association between DNA, RNA, and TF on chromatin. TF-RNA interactions are a conserved feature important for vertebrate development and disrupted in disease. We propose that the ability to bind DNA, RNA, and protein is a general property of many TFs and is fundamental to their gene regulatory function.
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Affiliation(s)
- Ozgur Oksuz
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | | | - Robert Warneford-Thomson
- Epigenetics Institute, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19104, USA; Department of Cell and Developmental Biology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Ming M Zheng
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Hailey Erb
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Adrienne Vancura
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Kalon J Overholt
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Susana Wilson Hawken
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Program of Computational & Systems Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Salman F Banani
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Richard Lauman
- Epigenetics Institute, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19104, USA; Department of Cell and Developmental Biology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Lauren N Reich
- Epigenetics Institute, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19104, USA; Department of Cell and Developmental Biology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Anne L Robertson
- Stem Cell Program, Division of Hematology/Oncology, Boston Children's Hospital and Dana Farber Cancer Institute, Boston, MA 02115, USA; Howard Hughes Medical Institute, Boston, MA 02115, USA
| | - Nancy M Hannett
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Tong I Lee
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Leonard I Zon
- Stem Cell Program, Division of Hematology/Oncology, Boston Children's Hospital and Dana Farber Cancer Institute, Boston, MA 02115, USA; Harvard Medical School, Boston, MA 02115, USA; Howard Hughes Medical Institute, Boston, MA 02115, USA; Stem Cell and Regenerative Biology Department, Harvard University, Cambridge, MA 02138, USA
| | - Roberto Bonasio
- Epigenetics Institute, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19104, USA; Department of Cell and Developmental Biology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Richard A Young
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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16
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Ken ML, Roy R, Geng A, Ganser LR, Manghrani A, Cullen BR, Schulze-Gahmen U, Herschlag D, Al-Hashimi HM. RNA conformational propensities determine cellular activity. Nature 2023; 617:835-841. [PMID: 37198487 PMCID: PMC10429349 DOI: 10.1038/s41586-023-06080-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 04/12/2023] [Indexed: 05/19/2023]
Abstract
Cellular processes are the product of interactions between biomolecules, which associate to form biologically active complexes1. These interactions are mediated by intermolecular contacts, which if disrupted, lead to alterations in cell physiology. Nevertheless, the formation of intermolecular contacts nearly universally requires changes in the conformations of the interacting biomolecules. As a result, binding affinity and cellular activity crucially depend both on the strength of the contacts and on the inherent propensities to form binding-competent conformational states2,3. Thus, conformational penalties are ubiquitous in biology and must be known in order to quantitatively model binding energetics for protein and nucleic acid interactions4,5. However, conceptual and technological limitations have hindered our ability to dissect and quantitatively measure how conformational propensities affect cellular activity. Here we systematically altered and determined the propensities for forming the protein-bound conformation of HIV-1 TAR RNA. These propensities quantitatively predicted the binding affinities of TAR to the RNA-binding region of the Tat protein and predicted the extent of HIV-1 Tat-dependent transactivation in cells. Our results establish the role of ensemble-based conformational propensities in cellular activity and reveal an example of a cellular process driven by an exceptionally rare and short-lived RNA conformational state.
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Affiliation(s)
- Megan L Ken
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - Rohit Roy
- Center for Genomic and Computational Biology, Duke University School of Medicine, Durham, NC, USA
| | - Ainan Geng
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - Laura R Ganser
- Department of Biophysics, Johns Hopkins University, Baltimore, MD, USA
| | - Akanksha Manghrani
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - Bryan R Cullen
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC, USA
| | | | - Daniel Herschlag
- Department of Biochemistry, Stanford University, Stanford, CA, USA.
| | - Hashim M Al-Hashimi
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA.
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17
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Camara MB, Sobeh AM, Eichhorn CD. Progress in 7SK ribonucleoprotein structural biology. Front Mol Biosci 2023; 10:1154622. [PMID: 37051324 PMCID: PMC10083321 DOI: 10.3389/fmolb.2023.1154622] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Accepted: 03/16/2023] [Indexed: 03/29/2023] Open
Abstract
The 7SK ribonucleoprotein (RNP) is a dynamic and multifunctional regulator of RNA Polymerase II (RNAPII) transcription in metazoa. Comprised of the non-coding 7SK RNA, core proteins, and numerous accessory proteins, the most well-known 7SK RNP function is the sequestration and inactivation of the positive transcription elongation factor b (P-TEFb). More recently, 7SK RNP has been shown to regulate RNAPII transcription through P-TEFb-independent pathways. Due to its fundamental role in cellular function, dysregulation has been linked with human diseases including cancers, heart disease, developmental disorders, and viral infection. Significant advances in 7SK RNP structural biology have improved our understanding of 7SK RNP assembly and function. Here, we review progress in understanding the structural basis of 7SK RNA folding, biogenesis, and RNP assembly.
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Affiliation(s)
- Momodou B. Camara
- Department of Chemistry, University of Nebraska, Lincoln, NE, United States
| | - Amr M. Sobeh
- Department of Chemistry, University of Nebraska, Lincoln, NE, United States
| | - Catherine D. Eichhorn
- Department of Chemistry, University of Nebraska, Lincoln, NE, United States
- Nebraska Center for Integrated Biomolecular Communication, Lincoln, NE, United States
- *Correspondence: Catherine D. Eichhorn,
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18
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Ghanam RH, Eastep GN, Saad JS. Structural Insights into the Mechanism of HIV-1 Tat Secretion from the Plasma Membrane. J Mol Biol 2023; 435:167880. [PMID: 36370804 PMCID: PMC9822876 DOI: 10.1016/j.jmb.2022.167880] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 10/27/2022] [Accepted: 11/04/2022] [Indexed: 11/11/2022]
Abstract
Human immunodeficiency virus type 1 (HIV-1) trans-activator of transcription (Tat) is a small, intrinsically disordered basic protein that plays diverse roles in the HIV-1 replication cycle, including promotion of efficient viral RNA transcription. Tat is released by infected cells and subsequently absorbed by healthy cells, thereby contributing to HIV-1 pathogenesis including HIV-associated neurocognitive disorder. It has been shown that, in HIV-1-infected primary CD4 T-cells, Tat accumulates at the plasma membrane (PM) for secretion, a mechanism mediated by phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2). However, the structural basis for Tat interaction with the PM and thereby secretion is lacking. Herein, we employed NMR and biophysical methods to characterize Tat86 (86 amino acids) interactions with PI(4,5)P2 and lipid nanodiscs (NDs). Our data revealed that Arg49, Lys50 and Lys51 (RKK motif) constitute the PI(4,5)P2 binding site, that Tat86 interaction with lipid NDs is dependent on PI(4,5)P2 and phosphatidylserine (PS), and that the arginine-rich motif (RRQRRR) preferentially interacts with PS. Furthermore, we show that Trp11, previously implicated in Tat secretion, penetrates deeply in the membrane; substitution of Trp11 severely reduced Tat86 interaction with membranes. Deletion of the entire highly basic region and Trp11 completely abolished Tat86 binding to lipid NDs. Our data support a mechanism by which HIV-1 Tat secretion from the PM is mediated by a tripartite signal consisting of binding of the RKK motif to PI(4,5)P2, arginine-rich motif to PS, and penetration of Trp11 in the membrane. Altogether, these findings provide new insights into the molecular requirements for Tat binding to membranes during secretion.
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Affiliation(s)
- Ruba H Ghanam
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Gunnar N Eastep
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Jamil S Saad
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, United States.
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19
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Mbonye U, Kizito F, Karn J. New insights into transcription elongation control of HIV-1 latency and rebound. Trends Immunol 2023; 44:60-71. [PMID: 36503686 DOI: 10.1016/j.it.2022.11.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 11/07/2022] [Accepted: 11/09/2022] [Indexed: 12/13/2022]
Abstract
Antiretroviral therapy reduces circulating HIV-1 to undetectable amounts but does not eliminate the virus due to the persistence of a stable reservoir of latently infected cells. The reservoir is maintained both by proliferation of latently infected cells and by reseeding from reactivated cells. A major challenge for the field is to find safe and effective methods to eliminate this source of rebounding HIV-1. Studies on the molecular mechanisms leading to HIV-1 latency and reactivation are being transformed using latency models in primary and patient CD4+ T cells. These studies have revealed the central role played by the biogenesis of the transcription elongation factor P-TEFb (Positive Transcription Elongation Factor b) and its recruitment to proviral HIV-1, for the maintenance of viral latency and the control of viral reactivation.
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Affiliation(s)
- Uri Mbonye
- Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, OH, USA
| | - Fredrick Kizito
- Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, OH, USA
| | - Jonathan Karn
- Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, OH, USA.
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20
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Rocchi C, Louvat C, Miele AE, Batisse J, Guillon C, Ballut L, Lener D, Negroni M, Ruff M, Gouet P, Fiorini F. The HIV-1 Integrase C-Terminal Domain Induces TAR RNA Structural Changes Promoting Tat Binding. Int J Mol Sci 2022; 23:13742. [PMID: 36430221 PMCID: PMC9692563 DOI: 10.3390/ijms232213742] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 10/28/2022] [Accepted: 11/03/2022] [Indexed: 11/10/2022] Open
Abstract
Recent evidence indicates that the HIV-1 Integrase (IN) binds the viral genomic RNA (gRNA), playing a critical role in the morphogenesis of the viral particle and in the stability of the gRNA once in the host cell. By combining biophysical, molecular biology, and biochemical approaches, we found that the 18-residues flexible C-terminal tail of IN acts as a sensor of the peculiar apical structure of the trans-activation response element RNA (TAR), interacting with its hexaloop. We show that the binding of the whole IN C-terminal domain modifies TAR structure, exposing critical nucleotides. These modifications favour the subsequent binding of the HIV transcriptional trans-activator Tat to TAR, finally displacing IN from TAR. Based on these results, we propose that IN assists the binding of Tat to TAR RNA. This working model provides a mechanistic sketch accounting for the emerging role of IN in the early stages of proviral transcription and could help in the design of anti-HIV-1 therapeutics against this new target of the viral infectious cycle.
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Affiliation(s)
- Cecilia Rocchi
- Molecular Microbiology and Structural Biochemistry, MMSB-IBCP, UMR 5086, CNRS, University of Lyon, 7 Passage du Vercors, CEDEX 07, 69367 Lyon, France
| | - Camille Louvat
- Molecular Microbiology and Structural Biochemistry, MMSB-IBCP, UMR 5086, CNRS, University of Lyon, 7 Passage du Vercors, CEDEX 07, 69367 Lyon, France
| | - Adriana Erica Miele
- Institute of Analytical Sciences, UMR 5280 CNRS UCBL University of Lyon, 5 Rue de la Doua, 69100 Villeurbanne, France
- Department of Biochemical Sciences, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy
| | - Julien Batisse
- Chromatin Stability and DNA Mobility, Department of Integrated Structural Biology, IGBMC, CNRS, UMR 7104—Inserm U 158, University of Strasbourg, 1 rue Laurent Fries, 67404 Illkirch, France
| | - Christophe Guillon
- Molecular Microbiology and Structural Biochemistry, MMSB-IBCP, UMR 5086, CNRS, University of Lyon, 7 Passage du Vercors, CEDEX 07, 69367 Lyon, France
| | - Lionel Ballut
- Molecular Microbiology and Structural Biochemistry, MMSB-IBCP, UMR 5086, CNRS, University of Lyon, 7 Passage du Vercors, CEDEX 07, 69367 Lyon, France
| | - Daniela Lener
- RNA Architecture and Reactivity, IBMC, CNRS, UPR 9002, University of Strasbourg, 2, Allée Konrad Roentgen, 67084 Strasbourg, France
| | - Matteo Negroni
- RNA Architecture and Reactivity, IBMC, CNRS, UPR 9002, University of Strasbourg, 2, Allée Konrad Roentgen, 67084 Strasbourg, France
| | - Marc Ruff
- Chromatin Stability and DNA Mobility, Department of Integrated Structural Biology, IGBMC, CNRS, UMR 7104—Inserm U 158, University of Strasbourg, 1 rue Laurent Fries, 67404 Illkirch, France
| | - Patrice Gouet
- Molecular Microbiology and Structural Biochemistry, MMSB-IBCP, UMR 5086, CNRS, University of Lyon, 7 Passage du Vercors, CEDEX 07, 69367 Lyon, France
| | - Francesca Fiorini
- Molecular Microbiology and Structural Biochemistry, MMSB-IBCP, UMR 5086, CNRS, University of Lyon, 7 Passage du Vercors, CEDEX 07, 69367 Lyon, France
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21
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Valyaeva AA, Tikhomirova MA, Potashnikova DM, Bogomazova AN, Snigiryova GP, Penin AA, Logacheva MD, Arifulin EA, Shmakova AA, Germini D, Kachalova AI, Saidova AA, Zharikova AA, Musinova YR, Mironov AA, Vassetzky YS, Sheval EV. Ectopic expression of HIV-1 Tat modifies gene expression in cultured B cells: implications for the development of B-cell lymphomas in HIV-1-infected patients. PeerJ 2022; 10:e13986. [PMID: 36275462 PMCID: PMC9586123 DOI: 10.7717/peerj.13986] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 08/11/2022] [Indexed: 01/19/2023] Open
Abstract
An increased frequency of B-cell lymphomas is observed in human immunodeficiency virus-1 (HIV-1)-infected patients, although HIV-1 does not infect B cells. Development of B-cell lymphomas may be potentially due to the action of the HIV-1 Tat protein, which is actively released from HIV-1-infected cells, on uninfected B cells. The exact mechanism of Tat-induced B-cell lymphomagenesis has not yet been precisely identified. Here, we ectopically expressed either Tat or its TatC22G mutant devoid of transactivation activity in the RPMI 8866 lymphoblastoid B cell line and performed a genome-wide analysis of host gene expression. Stable expression of both Tat and TatC22G led to substantial modifications of the host transcriptome, including pronounced changes in antiviral response and cell cycle pathways. We did not find any strong action of Tat on cell proliferation, but during prolonged culturing, Tat-expressing cells were displaced by non-expressing cells, indicating that Tat expression slightly inhibited cell growth. We also found an increased frequency of chromosome aberrations in cells expressing Tat. Thus, Tat can modify gene expression in cultured B cells, leading to subtle modifications in cellular growth and chromosome instability, which could promote lymphomagenesis over time.
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Affiliation(s)
- Anna A. Valyaeva
- School of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russia,Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia,Department of Cell Biology and Histology, School of Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Maria A. Tikhomirova
- School of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russia,Koltzov Institute of Developmental Biology, Moscow, Russia
| | - Daria M. Potashnikova
- Department of Cell Biology and Histology, School of Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Alexandra N. Bogomazova
- Federal Research and Clinical Center of Physical-Chemical Medicine, Moscow, Russia,Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Moscow, Russia
| | | | | | - Maria D. Logacheva
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia,Skolkovo Institute of Science and Technology, Moscow, Russia
| | - Eugene A. Arifulin
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Anna A. Shmakova
- Koltzov Institute of Developmental Biology, Moscow, Russia,UMR9018 (CNRS – Institut Gustave Roussy – Université Paris Saclay), Centre National de Recherche Scientifique, Villejuif, France, France
| | - Diego Germini
- UMR9018 (CNRS – Institut Gustave Roussy – Université Paris Saclay), Centre National de Recherche Scientifique, Villejuif, France, France
| | - Anastasia I. Kachalova
- Department of Cell Biology and Histology, School of Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Aleena A. Saidova
- Department of Cell Biology and Histology, School of Biology, Lomonosov Moscow State University, Moscow, Russia,Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Engelhardt Institute of Molecular Biology, Moscow, Russia
| | - Anastasia A. Zharikova
- School of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russia,Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Yana R. Musinova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia,Koltzov Institute of Developmental Biology, Moscow, Russia
| | - Andrey A. Mironov
- School of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russia,Institute for Information Transmission Problems, Moscow, Russia
| | - Yegor S. Vassetzky
- Koltzov Institute of Developmental Biology, Moscow, Russia,UMR9018 (CNRS – Institut Gustave Roussy – Université Paris Saclay), Centre National de Recherche Scientifique, Villejuif, France, France
| | - Eugene V. Sheval
- School of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russia,Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia,Department of Cell Biology and Histology, School of Biology, Lomonosov Moscow State University, Moscow, Russia
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22
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Kognole AA, Hazel A, MacKerell AD. SILCS-RNA: Toward a Structure-Based Drug Design Approach for Targeting RNAs with Small Molecules. J Chem Theory Comput 2022; 18:5672-5691. [PMID: 35913731 PMCID: PMC9474704 DOI: 10.1021/acs.jctc.2c00381] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
RNA molecules can act as potential drug targets in different diseases, as their dysregulated expression or misfolding can alter various cellular processes. Noncoding RNAs account for ∼70% of the human genome, and these molecules can have complex tertiary structures that present a great opportunity for targeting by small molecules. In the present study, the site identification by ligand competitive saturation (SILCS) computational approach is extended to target RNA, termed SILCS-RNA. Extensions to the method include an enhanced oscillating excess chemical potential protocol for the grand canonical Monte Carlo calculations and individual simulations of the neutral and charged solutes from which the SILCS functional group affinity maps (FragMaps) are calculated for subsequent binding site identification and docking calculations. The method is developed and evaluated against seven RNA targets and their reported small molecule ligands. SILCS-RNA provides a detailed characterization of the functional group affinity pattern in the small molecule binding sites, recapitulating the types of functional groups present in the ligands. The developed method is also shown to be useful for identification of new potential binding sites and identifying ligand moieties that contribute to binding, granular information that can facilitate ligand design. However, limitations in the method are evident including the ability to map the regions of binding sites occupied by ligand phosphate moieties and to fully account for the wide range of conformational heterogeneity in RNA associated with binding of different small molecules, emphasizing inherent challenges associated with applying computer-aided drug design methods to RNA. While limitations are present, the current study indicates how the SILCS-RNA approach may enhance drug discovery efforts targeting RNAs with small molecules.
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Affiliation(s)
- Abhishek A Kognole
- Computer Aided Drug Design Center, Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland Baltimore, Baltimore, Maryland 21201, United States
| | - Anthony Hazel
- Computer Aided Drug Design Center, Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland Baltimore, Baltimore, Maryland 21201, United States
| | - Alexander D MacKerell
- Computer Aided Drug Design Center, Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland Baltimore, Baltimore, Maryland 21201, United States
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23
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Pham VV, Gao M, Meagher JL, Smith JL, D'Souza VM. A structure-based mechanism for displacement of the HEXIM adapter from 7SK small nuclear RNA. Commun Biol 2022; 5:819. [PMID: 35970937 PMCID: PMC9378691 DOI: 10.1038/s42003-022-03734-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 07/19/2022] [Indexed: 11/09/2022] Open
Abstract
Productive transcriptional elongation of many cellular and viral mRNAs requires transcriptional factors to extract pTEFb from the 7SK snRNP by modulating the association between HEXIM and 7SK snRNA. In HIV-1, Tat binds to 7SK by displacing HEXIM. However, without the structure of the 7SK-HEXIM complex, the constraints that must be overcome for displacement remain unknown. Furthermore, while structure details of the TatNL4-3-7SK complex have been elucidated, it is unclear how subtypes with more HEXIM-like Tat sequences accomplish displacement. Here we report the structures of HEXIM, TatG, and TatFin arginine rich motifs in complex with the apical stemloop-1 of 7SK. While most interactions between 7SK with HEXIM and Tat are similar, critical differences exist that guide function. First, the conformational plasticity of 7SK enables the formation of three different base pair configurations at a critical remodeling site, which allows for the modulation required for HEXIM binding and its subsequent displacement by Tat. Furthermore, the specific sequence variations observed in various Tat subtypes all converge on remodeling 7SK at this region. Second, we show that HEXIM primes its own displacement by causing specific local destabilization upon binding - a feature that is then exploited by Tat to bind 7SK more efficiently.
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Affiliation(s)
- Vincent V Pham
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, 02138, USA
| | - Michael Gao
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, 02138, USA
| | - Jennifer L Meagher
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Janet L Smith
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, 48109, USA
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Victoria M D'Souza
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, 02138, USA.
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24
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Chen YL, He W, Kirmizialtin S, Pollack L. Insights into the structural stability of major groove RNA triplexes by WAXS-guided MD simulations. CELL REPORTS. PHYSICAL SCIENCE 2022; 3:100971. [PMID: 35936555 PMCID: PMC9351628 DOI: 10.1016/j.xcrp.2022.100971] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
RNA triple helices are commonly observed tertiary motifs that are associated with critical biological functions, including signal transduction. Because the recognition of their biological importance is relatively recent, their full range of structural properties has not yet been elucidated. The integration of solution wide-angle X-ray scattering (WAXS) with molecular dynamics (MD) simulations, described here, provides a new way to capture the structures of major-groove RNA triplexes that evade crystallographic characterization. This method yields excellent agreement between measured and computed WAXS profiles and allows for an atomically detailed visualization of these motifs. Using correlation maps, the relationship between well-defined features in the scattering profiles and real space characteristics of RNA molecules is defined, including the subtle conformational variations in the double-stranded RNA upon the incorporation of a third strand by base triples. This readily applicable approach has the potential to provide insight into interactions that stabilize RNA tertiary structure that enables function.
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Affiliation(s)
- Yen-Lin Chen
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853, USA
- These authors contributed equally
| | - Weiwei He
- Department of Chemistry, New York University, New York, NY 10003, USA
- Chemistry Program, Science Division, New York University Abu Dhabi, Abu Dhabi 129188, UAE
- These authors contributed equally
| | - Serdal Kirmizialtin
- Chemistry Program, Science Division, New York University Abu Dhabi, Abu Dhabi 129188, UAE
| | - Lois Pollack
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853, USA
- Lead contact
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25
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Ning S, Wang H, Zeng C, Zhao Y. Prediction of allosteric druggable pockets of cyclin-dependent kinases. Brief Bioinform 2022; 23:6643454. [PMID: 35830869 DOI: 10.1093/bib/bbac290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 06/07/2022] [Accepted: 06/24/2022] [Indexed: 11/13/2022] Open
Abstract
Cyclin-dependent kinase (Cdk) proteins play crucial roles in the cell cycle progression and are thus attractive drug targets for therapy against such aberrant cell cycle processes as cancer. Since most of the available Cdk inhibitors target the highly conserved catalytic ATP pocket and their lack of specificity often lead to side effects, it is imperative to identify and characterize less conserved non-catalytic pockets capable of interfering with the kinase activity allosterically. However, a systematic analysis of these allosteric druggable pockets is still in its infancy. Here, we summarize the existing Cdk pockets and their selectivity. Then, we outline a network-based pocket prediction approach (NetPocket) and illustrate its utility for systematically identifying the allosteric druggable pockets with case studies. Finally, we discuss potential future directions and their challenges.
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Affiliation(s)
- Shangbo Ning
- Institute of Biophysics and Department of Physics, Central China Normal University, Wuhan, 430079, China
| | - Huiwen Wang
- School of Physics and Engineering, Henan University of Science and Technology, Luoyang 471023, China
| | - Chen Zeng
- Department of Physics, The George Washington University, Washington, DC 20052, USA
| | - Yunjie Zhao
- Institute of Biophysics and Department of Physics, Central China Normal University, Wuhan, 430079, China
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26
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Rocchi C, Gouet P, Parissi V, Fiorini F. The C-Terminal Domain of HIV-1 Integrase: A Swiss Army Knife for the Virus? Viruses 2022; 14:v14071397. [PMID: 35891378 PMCID: PMC9316232 DOI: 10.3390/v14071397] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 06/22/2022] [Accepted: 06/22/2022] [Indexed: 12/31/2022] Open
Abstract
Retroviral integrase is a multimeric enzyme that catalyzes the integration of reverse-transcribed viral DNA into the cellular genome. Beyond integration, the Human immunodeficiency virus type 1 (HIV-1) integrase is also involved in many other steps of the viral life cycle, such as reverse transcription, nuclear import, virion morphogenesis and proviral transcription. All these additional functions seem to depend on the action of the integrase C-terminal domain (CTD) that works as a molecular hub, interacting with many different viral and cellular partners. In this review, we discuss structural issues concerning the CTD, with particular attention paid to its interaction with nucleic acids. We also provide a detailed map of post-translational modifications and interaction with molecular partners.
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Affiliation(s)
- Cecilia Rocchi
- Molecular Microbiology and Structural Biochemistry (MMSB), CNRS, University of Lyon 1, UMR 5086, 69367 Lyon, France; (C.R.); (P.G.)
- Viral DNA Integration and Chromatin Dynamics Network (DyNAVir), 33076 Bordeaux, France;
| | - Patrice Gouet
- Molecular Microbiology and Structural Biochemistry (MMSB), CNRS, University of Lyon 1, UMR 5086, 69367 Lyon, France; (C.R.); (P.G.)
- Viral DNA Integration and Chromatin Dynamics Network (DyNAVir), 33076 Bordeaux, France;
| | - Vincent Parissi
- Viral DNA Integration and Chromatin Dynamics Network (DyNAVir), 33076 Bordeaux, France;
- Fundamental Microbiology and Pathogenicity (MFP), CNRS, University of Bordeaux, UMR5234, 33405 Bordeaux, France
| | - Francesca Fiorini
- Molecular Microbiology and Structural Biochemistry (MMSB), CNRS, University of Lyon 1, UMR 5086, 69367 Lyon, France; (C.R.); (P.G.)
- Viral DNA Integration and Chromatin Dynamics Network (DyNAVir), 33076 Bordeaux, France;
- Correspondence: ; Tel.: +33-4-72722624; Fax: +33-4-72722616
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27
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Van Damme R, Li K, Zhang M, Bai J, Lee WH, Yesselman JD, Lu Z, Velema WA. Chemical reversible crosslinking enables measurement of RNA 3D distances and alternative conformations in cells. Nat Commun 2022; 13:911. [PMID: 35177610 PMCID: PMC8854666 DOI: 10.1038/s41467-022-28602-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 01/19/2022] [Indexed: 02/06/2023] Open
Abstract
Three-dimensional (3D) structures dictate the functions of RNA molecules in a wide variety of biological processes. However, direct determination of RNA 3D structures in vivo is difficult due to their large sizes, conformational heterogeneity, and dynamics. Here we present a method, Spatial 2'-Hydroxyl Acylation Reversible Crosslinking (SHARC), which uses chemical crosslinkers of defined lengths to measure distances between nucleotides in cellular RNA. Integrating crosslinking, exonuclease (exo) trimming, proximity ligation, and high throughput sequencing, SHARC enables transcriptome-wide tertiary structure contact maps at high accuracy and precision, revealing heterogeneous RNA structures and interactions. SHARC data provide constraints that improves Rosetta-based RNA 3D structure modeling at near-nanometer resolution. Integrating SHARC-exo with other crosslinking-based methods, we discover compact folding of the 7SK RNA, a critical regulator of transcriptional elongation. These results establish a strategy for measuring RNA 3D distances and alternative conformations in their native cellular context.
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Affiliation(s)
- Ryan Van Damme
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA, 90033, USA
| | - Kongpan Li
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA, 90033, USA
| | - Minjie Zhang
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA, 90033, USA
| | - Jianhui Bai
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA, 90033, USA
| | - Wilson H Lee
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA, 90033, USA
| | - Joseph D Yesselman
- Department of Chemistry, University of Nebraska-Lincoln, 832A Hamilton Hall, Lincoln, NE, 68588, USA
| | - Zhipeng Lu
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA, 90033, USA.
| | - Willem A Velema
- Institute for Molecules and Materials, Radboud University Nijmegen, Nijmegen, The Netherlands.
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28
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Kotar A, Ma S, Keane SC. pH dependence of C•A, G•A and A•A mismatches in the stem of precursor microRNA-31. Biophys Chem 2022; 283:106763. [DOI: 10.1016/j.bpc.2022.106763] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 01/13/2022] [Accepted: 01/15/2022] [Indexed: 12/22/2022]
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29
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Ning S, Zeng C, Zeng C, Zhao Y. The TAR binding dynamics and its implication in Tat degradation mechanism. Biophys J 2021; 120:5158-5168. [PMID: 34762866 PMCID: PMC8715215 DOI: 10.1016/j.bpj.2021.11.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 09/25/2021] [Accepted: 11/03/2021] [Indexed: 10/19/2022] Open
Abstract
Human immunodeficiency virus (HIV) is a retrovirus that progressively attacks the human immune system. It is known that the HIV viral protein Tat recruits the host elongation factor, positive transcription elongation factor b (P-TEFb), onto the nascent HIV viral transactivation response element (TAR) RNA to overcome the elongation pause for active transcription of the entire viral genome. Interestingly, there exists an amplifying feedback loop between Tat and TAR-a reduction in Tat increases the elongation pause, resulting in more TAR RNA fragments instead of the entire viral genome transcript, and the TAR fragments as a scaffold for PRC2 complex in turn promote Tat ubiquitination and degradation. In this study, the structural ensembles and binding dynamics of various interfaces in the Tat/TAR/P-TEFb complex are probed by all-atom accelerated sampling molecular dynamics simulations. The results show that a protein-binding inhibitor F07#13 targeting the Tat/P-TEFb interface initiates the above feedback loop and shuts down the active transcription. Another RNA binding inhibitor, JB181, targeting the Tat/TAR interface, can prevent TAR from pulling down the Tat from P-TEFb protein and further reducing Tat degradation. The detailed mechanism of the complex dynamics helps elucidate how Tat and TAR coordinate the regulation between HIV genome transcription versus possible HIV latency.
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Affiliation(s)
- Shangbo Ning
- Institute of Biophysics and Department of Physics, Central China Normal University, Wuhan, China
| | - Chengwei Zeng
- Institute of Biophysics and Department of Physics, Central China Normal University, Wuhan, China
| | - Chen Zeng
- Department of Physics, The George Washington University, Washington, DC
| | - Yunjie Zhao
- Institute of Biophysics and Department of Physics, Central China Normal University, Wuhan, China.
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30
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Kognole AA, Lee J, Park SJ, Jo S, Chatterjee P, Lemkul JA, Huang J, MacKerell AD, Im W. CHARMM-GUI Drude prepper for molecular dynamics simulation using the classical Drude polarizable force field. J Comput Chem 2021; 43:359-375. [PMID: 34874077 DOI: 10.1002/jcc.26795] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 11/10/2021] [Accepted: 11/25/2021] [Indexed: 12/18/2022]
Abstract
Explicit treatment of electronic polarizability in empirical force fields (FFs) represents an extension over a traditional additive or pairwise FF and provides a more realistic model of the variations in electronic structure in condensed phase, macromolecular simulations. To facilitate utilization of the polarizable FF based on the classical Drude oscillator model, Drude Prepper has been developed in CHARMM-GUI. Drude Prepper ingests additive CHARMM protein structures file (PSF) and pre-equilibrated coordinates in CHARMM, PDB, or NAMD format, from which the molecular components of the system are identified. These include all residues and patches connecting those residues along with water, ions, and other solute molecules. This information is then used to construct the Drude FF-based PSF using molecular generation capabilities in CHARMM, followed by minimization and equilibration. In addition, inputs are generated for molecular dynamics (MD) simulations using CHARMM, GROMACS, NAMD, and OpenMM. Validation of the Drude Prepper protocol and inputs is performed through conversion and MD simulations of various heterogeneous systems that include proteins, nucleic acids, lipids, polysaccharides, and atomic ions using the aforementioned simulation packages. Stable simulations are obtained in all studied systems, including 5 μs simulation of ubiquitin, verifying the integrity of the generated Drude PSFs. In addition, the ability of the Drude FF to model variations in electronic structure is shown through dipole moment analysis in selected systems. The capabilities and availability of Drude Prepper in CHARMM-GUI is anticipated to greatly facilitate the application of the Drude FF to a range of condensed phase, macromolecular systems.
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Affiliation(s)
- Abhishek A Kognole
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, Maryland, USA
| | - Jumin Lee
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania, USA
| | - Sang-Jun Park
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania, USA
| | - Sunhwan Jo
- Leadership Computing Facility, Argonne National Laboratory, Argonne, Illinois, USA
| | - Payal Chatterjee
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, Maryland, USA
| | - Justin A Lemkul
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, USA
| | - Jing Huang
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Zhejiang, Hangzhou, China
| | - Alexander D MacKerell
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, Maryland, USA
| | - Wonpil Im
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania, USA
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31
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Chavali SS, Mali SM, Bonn R, Saseendran A, Bennett RP, Smith HC, Fasan R, Wedekind JE. Cyclic peptides with a distinct arginine-fork motif recognize the HIV trans-activation response RNA in vitro and in cells. J Biol Chem 2021; 297:101390. [PMID: 34767799 DOI: 10.1016/j.jbc.2021.101390] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 11/02/2021] [Accepted: 11/04/2021] [Indexed: 12/21/2022] Open
Abstract
RNA represents a potential target for new antiviral therapies, which are urgently needed to address public health threats such as the human immunodeficiency virus (HIV). We showed previously that the interaction between the viral Tat protein and the HIV-1 trans-activation response (TAR) RNA was blocked by the cyclic peptide TB-CP-6.9a. This peptide was derived from a TAR-binding loop that emerged during lab-evolution of a TAR-binding protein (TBP) family. Here we synthesized and characterized a next-generation, cyclic-peptide library based on the TBP scaffold. We sought to identify conserved RNA-binding interactions, and the influence of cyclization linkers on RNA binding and antiviral activity. A diverse group of cyclization linkers, encompassing disulfide bonds to bicyclic aromatic staples, was used to restrain the cyclic peptide geometry. Thermodynamic profiling revealed specific arginine-rich sequences with low to sub-micromolar affinity driven by enthalpic and entropic contributions. The best compounds exhibited no appreciable off-target binding to related molecules, such as BIV TAR and human 7SK RNAs. A specific arginine-to-lysine change in the highest affinity cyclic peptide reduced TAR binding by 10-fold, suggesting that TBP-derived cyclic peptides use an arginine-fork motif to recognize the TAR major-groove while differentiating the mode of binding from other TAR-targeting molecules. Finally, we showed that HIV infectivity in cell culture was reduced in the presence of cyclic peptides constrained by methylene or naphthalene-based linkers. Our findings provide insight into the molecular determinants required for HIV-1 TAR recognition and antiviral activity. These findings are broadly relevant to the development of antivirals that target RNA molecules.
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Affiliation(s)
- Sai Shashank Chavali
- Department of Biochemistry & Biophysics and Center for RNA Biology, University of Rochester School of Medicine & Dentistry, Rochester NY 14642, USA
| | - Sachitanand M Mali
- Department of Chemistry, University of Rochester, Rochester NY 14627, USA
| | - Rachel Bonn
- Department of Biochemistry & Biophysics and Center for RNA Biology, University of Rochester School of Medicine & Dentistry, Rochester NY 14642, USA
| | | | | | - Harold C Smith
- Department of Biochemistry & Biophysics and Center for RNA Biology, University of Rochester School of Medicine & Dentistry, Rochester NY 14642, USA; OyaGen, Inc., Rochester NY 14623, USA
| | - Rudi Fasan
- Department of Chemistry, University of Rochester, Rochester NY 14627, USA
| | - Joseph E Wedekind
- Department of Biochemistry & Biophysics and Center for RNA Biology, University of Rochester School of Medicine & Dentistry, Rochester NY 14642, USA.
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32
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Covelo-Molares H, Obrdlik A, Poštulková I, Dohnálková M, Gregorová P, Ganji R, Potěšil D, Gawriyski L, Varjosalo M, Vaňáčová Š. The comprehensive interactomes of human adenosine RNA methyltransferases and demethylases reveal distinct functional and regulatory features. Nucleic Acids Res 2021; 49:10895-10910. [PMID: 34634806 PMCID: PMC8565353 DOI: 10.1093/nar/gkab900] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 09/18/2021] [Accepted: 09/22/2021] [Indexed: 12/26/2022] Open
Abstract
N6-methyladenosine (m6A) and N6,2′-O-dimethyladenosine (m6Am) are two abundant modifications found in mRNAs and ncRNAs that can regulate multiple aspects of RNA biology. They function mainly by regulating interactions with specific RNA-binding proteins. Both modifications are linked to development, disease and stress response. To date, three methyltransferases and two demethylases have been identified that modify adenosines in mammalian mRNAs. Here, we present a comprehensive analysis of the interactomes of these enzymes. PCIF1 protein network comprises mostly factors involved in nascent RNA synthesis by RNA polymerase II, whereas ALKBH5 is closely linked with most aspects of pre-mRNA processing and mRNA export to the cytoplasm. METTL16 resides in subcellular compartments co-inhabited by several other RNA modifiers and processing factors. FTO interactome positions this demethylase at a crossroad between RNA transcription, RNA processing and DNA replication and repair. Altogether, these enzymes share limited spatial interactomes, pointing to specific molecular mechanisms of their regulation.
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Affiliation(s)
- Helena Covelo-Molares
- Central European Institute of Technology (CEITEC), Masaryk University, Brno 62500, Czech Republic
| | - Ales Obrdlik
- Central European Institute of Technology (CEITEC), Masaryk University, Brno 62500, Czech Republic
| | - Ivana Poštulková
- Central European Institute of Technology (CEITEC), Masaryk University, Brno 62500, Czech Republic
| | - Michaela Dohnálková
- Central European Institute of Technology (CEITEC), Masaryk University, Brno 62500, Czech Republic
| | - Pavlína Gregorová
- Central European Institute of Technology (CEITEC), Masaryk University, Brno 62500, Czech Republic
| | - Ranjani Ganji
- Central European Institute of Technology (CEITEC), Masaryk University, Brno 62500, Czech Republic
| | - David Potěšil
- Central European Institute of Technology (CEITEC), Masaryk University, Brno 62500, Czech Republic
| | - Lisa Gawriyski
- Institute of Biotechnology & HiLIFE - Helsinki Institute of Life Science, University of Helsinki, Helsinki 00014, Finland
| | - Markku Varjosalo
- Institute of Biotechnology & HiLIFE - Helsinki Institute of Life Science, University of Helsinki, Helsinki 00014, Finland
| | - Štěpánka Vaňáčová
- Central European Institute of Technology (CEITEC), Masaryk University, Brno 62500, Czech Republic
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33
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Molecular coevolution of nuclear and nucleolar localization signals inside basic domain of HIV-1 Tat. J Virol 2021; 96:e0150521. [PMID: 34613791 DOI: 10.1128/jvi.01505-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
During evolution, viruses had to adapt to an increasingly complex environment of eukaryotic cells. Viral proteins that need to enter the cell nucleus or associate with nucleoli possess nuclear localization signals (NLSs) and nucleolar localization signals (NoLSs) for nuclear and nucleolar accumulation, respectively. As viral proteins are relatively small, acquisition of novel sequences seems to be a more complicated task for viruses than for eukaryotes. Here, we carried out a comprehensive analysis of the basic domain (BD) of HIV-1 Tat to show how viral proteins might evolve with NLSs and NoLSs without an increase in protein size. The HIV-1 Tat BD is involved in several functions, the most important being the transactivation of viral transcription. The BD also functions as an NLS, although it is substantially longer than a typical NLS. It seems that different regions in the BD could function as NLSs due to its enrichment with positively charged amino acids. Additionally, the high positive net charge inevitably causes the BD to function as an NoLS through a charge-specific mechanism. The integration of NLSs and NoLSs into functional domains enriched with positively charged amino acids might be a mechanism that allows the condensation of different functional sequences in small protein regions and, as a result, to reduce protein size, influencing the origin and evolution of NLSs and NoLSs in viruses. IMPORTANCE Here, we investigated the molecular mechanism of NLS and NoLS integration into the basic domain of HIV-1 Tat (49RKKRRQRRR57), and found that these two supplementary functions (i.e., function of NLS and NoLS) are embedded in the basic domain amino acid sequence. The integration of NLSs and NoLSs into functional domains of viral proteins enriched with positively charged amino acids is a mechanism that allows the concentration of different functions within small protein regions. Integration of NLS and NoLS into functional protein domains might have influenced the viral evolution, as this could prevent an increase in the protein size.
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34
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Liu Y, Kotar A, Hodges TL, Abdallah K, Taleb MH, Bitterman BA, Jaime S, Schaubroeck KJ, Mathew E, Morgenstern NW, Lohmeier A, Page JL, Ratanapanichkich M, Arhin G, Johnson BL, Cherepanov S, Moss SC, Zuniga G, Tilson NJ, Yeoh ZC, Johnson BA, Keane SC. NMR chemical shift assignments of RNA oligonucleotides to expand the RNA chemical shift database. BIOMOLECULAR NMR ASSIGNMENTS 2021; 15:479-490. [PMID: 34449019 DOI: 10.1007/s12104-021-10049-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 08/22/2021] [Indexed: 06/13/2023]
Abstract
RNAs play myriad functional and regulatory roles in the cell. Despite their significance, three-dimensional structure elucidation of RNA molecules lags significantly behind that of proteins. NMR-based studies are often rate-limited by the assignment of chemical shifts. Automation of the chemical shift assignment process can greatly facilitate structural studies, however, accurate chemical shift predictions rely on a robust and complete chemical shift database for training. We searched the Biological Magnetic Resonance Data Bank (BMRB) to identify sequences that had no (or limited) chemical shift information. Here, we report the chemical shift assignments for 12 RNA hairpins designed specifically to help populate the BMRB.
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Affiliation(s)
- Yaping Liu
- Biophysics Program, University of Michigan, 930 N. University Avenue, Ann Arbor, MI, 48109, USA
| | - Anita Kotar
- Biophysics Program, University of Michigan, 930 N. University Avenue, Ann Arbor, MI, 48109, USA
- Current Address: Slovenian NMR Centre, National Institute of Chemistry, Hajdrihova 19, 1000, Ljubljana, Slovenia
| | - Tracy L Hodges
- Biophysics Program, University of Michigan, 930 N. University Avenue, Ann Arbor, MI, 48109, USA
| | - Kyrillos Abdallah
- Biophysics Program, University of Michigan, 930 N. University Avenue, Ann Arbor, MI, 48109, USA
| | - Mallak H Taleb
- Biophysics Program, University of Michigan, 930 N. University Avenue, Ann Arbor, MI, 48109, USA
| | - Brayden A Bitterman
- Biophysics Program, University of Michigan, 930 N. University Avenue, Ann Arbor, MI, 48109, USA
| | - Sara Jaime
- Biophysics Program, University of Michigan, 930 N. University Avenue, Ann Arbor, MI, 48109, USA
| | - Kyle J Schaubroeck
- Biophysics Program, University of Michigan, 930 N. University Avenue, Ann Arbor, MI, 48109, USA
| | - Ethan Mathew
- Biophysics Program, University of Michigan, 930 N. University Avenue, Ann Arbor, MI, 48109, USA
| | - Nicholas W Morgenstern
- Biophysics Program, University of Michigan, 930 N. University Avenue, Ann Arbor, MI, 48109, USA
| | - Anthony Lohmeier
- Biophysics Program, University of Michigan, 930 N. University Avenue, Ann Arbor, MI, 48109, USA
| | - Jordan L Page
- Biophysics Program, University of Michigan, 930 N. University Avenue, Ann Arbor, MI, 48109, USA
| | - Matt Ratanapanichkich
- Biophysics Program, University of Michigan, 930 N. University Avenue, Ann Arbor, MI, 48109, USA
| | - Grace Arhin
- Biophysics Program, University of Michigan, 930 N. University Avenue, Ann Arbor, MI, 48109, USA
| | - Breanna L Johnson
- Biophysics Program, University of Michigan, 930 N. University Avenue, Ann Arbor, MI, 48109, USA
| | - Stanislav Cherepanov
- Biophysics Program, University of Michigan, 930 N. University Avenue, Ann Arbor, MI, 48109, USA
| | - Stephen C Moss
- Biophysics Program, University of Michigan, 930 N. University Avenue, Ann Arbor, MI, 48109, USA
| | - Gisselle Zuniga
- Biophysics Program, University of Michigan, 930 N. University Avenue, Ann Arbor, MI, 48109, USA
| | - Nicholas J Tilson
- Biophysics Program, University of Michigan, 930 N. University Avenue, Ann Arbor, MI, 48109, USA
| | - Zoe C Yeoh
- Department of Biological Chemistry, University of Michigan, 1150 W. Medical Center Drive, Ann Arbor, MI, 48109, USA
| | - Bruce A Johnson
- Structural Biology Initiative, CUNY Advanced Science Research Center, 85 St. Nicholas Terrace, New York, NY, 10031, USA
| | - Sarah C Keane
- Biophysics Program, University of Michigan, 930 N. University Avenue, Ann Arbor, MI, 48109, USA.
- Department of Chemistry, University of Michigan, 930 N. University Avenue, Ann Arbor, MI, 48109, USA.
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TAR RNA Mediated Folding of a Single-Arginine-Mutant HIV-1 Tat Protein within HeLa Cells Experiencing Intracellular Crowding. Int J Mol Sci 2021; 22:ijms22189998. [PMID: 34576162 PMCID: PMC8468913 DOI: 10.3390/ijms22189998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2021] [Revised: 09/03/2021] [Accepted: 09/11/2021] [Indexed: 11/17/2022] Open
Abstract
The various effects of native protein folding on the stability and folding rate of intrinsically disordered proteins (IDPs) in crowded intracellular environments are important in biomedicine. Although most studies on protein folding have been conducted in vitro, providing valuable insights, studies on protein folding in crowded intracellular environments are scarce. This study aimed to explore the effects of intracellular molecular crowding on the folding of mutant transactivator HIV-1 Tat based on intracellular interactions, including TAR RNA, as proof of the previously reported chaperna-RNA concept. Considering that the Tat-TAR RNA motif binds RNA, we assessed the po tential function of TAR RNA as a chaperna for the refolding of R52Tat, a mutant in which the argi nine (R) residues at R52 have been replaced with alanine (A) by site-directed mutagenesis. We mon itored Tat-EGFP and Tat folding in HeLa cells via time-lapse fluorescence microscopy and biolayer interferometry using EGFP fusion as an indicator for folding status. These results show that the refolding of R52A Tat was stimulated well at a 0.3 μM TAR RNA concentration; wild-type Tat refolding was essentially abolished because of a reduction in the affinity for TAR RNA at that con centration. The folding and refolding of R52Tat were mainly promoted upon stimulation with TAR RNA. Our findings provide novel insights into the therapeutic potential of chaperna-mediated fold ing through the examination of as-yet-unexplored RNA-mediated protein folding as well as viral genetic variants that modulate viral evolutionary linkages for viral diseases inside a crowded intra cellular environment.
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Interplay between Host tRNAs and HIV-1: A Structural Perspective. Viruses 2021; 13:v13091819. [PMID: 34578400 PMCID: PMC8473020 DOI: 10.3390/v13091819] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 09/06/2021] [Accepted: 09/09/2021] [Indexed: 12/23/2022] Open
Abstract
The cellular metabolism of host tRNAs and life cycle of HIV-1 cross paths at several key virus-host interfaces. Emerging data suggest a multi-faceted interplay between host tRNAs and HIV-1 that plays essential roles, both structural and regulatory, in viral genome replication, genome packaging, and virion biogenesis. HIV-1 not only hijacks host tRNAs and transforms them into obligatory reverse transcription primers but further commandeers tRNAs to regulate the localization of its major structural protein, Gag, via a specific interface. This review highlights recent advances in understanding tRNA-HIV-1 interactions, primarily from a structural perspective, which start to elucidate their underlying molecular mechanisms, intrinsic specificities, and biological significances. Such understanding may provide new avenues toward developing HIV/AIDS treatments and therapeutics including small molecules and RNA biologics that target these host-virus interfaces.
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Chen R, Zhang Y, Chen P, Pang Y, Li H, Chen Z, Zhang X, Zhang H, Li W. [7SK truncation at 128-179 nt suppresses embryonic stem cell proliferation in vitro by downregulating CDC6]. NAN FANG YI KE DA XUE XUE BAO = JOURNAL OF SOUTHERN MEDICAL UNIVERSITY 2021; 41:1125-1130. [PMID: 34549701 DOI: 10.12122/j.issn.1673-4254.2021.08.01] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
OBJECTIVE To explore the role of small nuclear noncoding RNA 7SK in embryonic stem cell (ESCs) proliferation and the value of 7SK as a target for early diagnosis and treatment for primordial dwarfism (PD). METHODS ESC line R1 was transfected with the CRISPR/Cas9 system, and sequencing of the PCR product and glycerol gradient analysis were performed to identify novel 7SK deletion mutations. A lentivirus system was used to knock down cyclin-dependent kinase 9 (CDK9) in clones with 7SK deletion mutations, and the effect of CDK9 knockdown on the protein level of cell division cycle 6 (CDC6) was analyzed with Western blotting. RESULTS We identified a novel deletion mutation of 7SK at 128-179 nt in the ESCs, which resulted in deficiency of cell proliferation. 7SK truncation at 128-179 nt significantly reduced the protein expressions of La-related protein 7 (LARP7) and CDC6. CONCLUSIONS 7SK truncation at 128-179 nt can significantly impair proliferation of ESCs by downregulating CDC6. 7SK is a key regulator of proliferation and mediates the growth of ESCs through a mechanism dependent on CDK9 activity, suggesting the value of 7SK truncation at 128-179 nt as a potential target for early diagnosis and treatment of PD.
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Affiliation(s)
- Rui Chen
- First Affiliated Hospital of Xi'an Medical University, Xi'an 710077, China
| | - Yurong Zhang
- First Affiliated Hospital of Xi'an Medical University, Xi'an 710077, China
| | - Peng Chen
- Institute of Basic Medical Science, Xi'an Medical University, Xi'an 710021, China
| | - Yixin Pang
- Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710004, China
| | - Hongbao Li
- Department of Physiology and Pathophysiology, Xi'an Jiaotong University School of Basic Medical Sciences, Xi'an 710061, China
| | - Ziwei Chen
- School of Clinical Medicine, Xi'an MedicalUniversity, Xi'an710021, China
| | - Xiaoyong Zhang
- First Affiliated Hospital of Xi'an Medical University, Xi'an 710077, China
| | - Hongyi Zhang
- First Affiliated Hospital of Xi'an Medical University, Xi'an 710077, China
| | - Wujun Li
- First Affiliated Hospital of Xi'an Medical University, Xi'an 710077, China
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Levintov L, Vashisth H. Role of conformational heterogeneity in ligand recognition by viral RNA molecules. Phys Chem Chem Phys 2021; 23:11211-11223. [PMID: 34010381 DOI: 10.1039/d1cp00679g] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Ribonucleic acid (RNA) molecules are known to undergo conformational changes in response to various environmental stimuli including temperature, pH, and ligands. In particular, viral RNA molecules are a key example of conformationally adapting molecules that have evolved to switch between many functional conformations. The transactivation response element (TAR) RNA from the type-1 human immunodeficiency virus (HIV-1) is a viral RNA molecule that is being increasingly explored as a potential therapeutic target due to its role in the viral replication process. In this work, we have studied the dynamics in TAR RNA in apo and liganded states by performing explicit-solvent molecular dynamics (MD) simulations initiated with 27 distinct structures. We determined that the TAR RNA structure is significantly stabilized on ligand binding with especially decreased fluctuations in its two helices. This rigidity is further coupled with the decreased flipping of bulge nucleotides, which were observed to flip more frequently in the absence of ligands. We found that initially-distinct structures of TAR RNA converged to similar conformations on removing ligands. We also report that conformational dynamics in unliganded TAR structures leads to the formation of binding pockets capable of accommodating ligands of various sizes.
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Affiliation(s)
- Lev Levintov
- Department of Chemical Engineering, University of New Hampshire, Durham 03824, New Hampshire, USA.
| | - Harish Vashisth
- Department of Chemical Engineering, University of New Hampshire, Durham 03824, New Hampshire, USA.
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39
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The Peptide TAT-I24 with Antiviral Activity against DNA Viruses Binds Double-Stranded DNA with High Affinity. Biologics 2021. [DOI: 10.3390/biologics1010003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The peptide TAT-I24, composed of the 9-mer peptide I24 and the TAT (48-60) peptide, exerts broad-spectrum antiviral activity against several DNA viruses. The current model of the mode of action suggests a reduction of viral entry and also a possible interaction with the viral DNA upon virus entry. To further support this model, the present study investigates the DNA binding properties of TAT-I24. DNA binding was analysed by gel retardation of a peptide-complexed DNA, fluorescence reduction of DNA labelled with intercalating dyes and determination of binding kinetics by surface plasmon resonance. Molecular dynamics simulations of DNA-peptide complexes predict high-affinity binding and destabilization of the DNA by TAT-I24. The effect on viral DNA levels of infected cells were studied by real-time PCR and staining of viral DNA by bromodeoxyuridine. TAT-I24 binds double-stranded DNA with high affinity, leading to inhibition of polymerase binding and thereby blocking of de novo nucleic acid synthesis. Analysis of early steps of virus entry using a bromodeoxyuridine-labelled virus as well as quantification of viral genomes in the cells indicate direct binding of the peptide to the viral DNA. Saturation of the peptide with exogenous DNA can fully neutralize the inhibitory effect. The antiviral activity of TAT-I24 is linked to its ability to bind DNA with high affinity. This mechanism could be the basis for the development of novel antiviral agents.
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40
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Dixit U, Bhutoria S, Wu X, Qiu L, Spira M, Mathew S, Harris R, Adams LJ, Cahill S, Pathak R, Rajesh Kumar P, Nguyen M, Acharya SA, Brenowitz M, Almo SC, Zou X, Steven AC, Cowburn D, Girvin M, Kalpana GV. INI1/SMARCB1 Rpt1 domain mimics TAR RNA in binding to integrase to facilitate HIV-1 replication. Nat Commun 2021; 12:2743. [PMID: 33980829 PMCID: PMC8115288 DOI: 10.1038/s41467-021-22733-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Accepted: 03/24/2021] [Indexed: 11/09/2022] Open
Abstract
INI1/SMARCB1 binds to HIV-1 integrase (IN) through its Rpt1 domain and exhibits multifaceted role in HIV-1 replication. Determining the NMR structure of INI1-Rpt1 and modeling its interaction with the IN-C-terminal domain (IN-CTD) reveal that INI1-Rpt1/IN-CTD interface residues overlap with those required for IN/RNA interaction. Mutational analyses validate our model and indicate that the same IN residues are involved in both INI1 and RNA binding. INI1-Rpt1 and TAR RNA compete with each other for IN binding with similar IC50 values. INI1-interaction-defective IN mutant viruses are impaired for incorporation of INI1 into virions and for particle morphogenesis. Computational modeling of IN-CTD/TAR complex indicates that the TAR interface phosphates overlap with negatively charged surface residues of INI1-Rpt1 in three-dimensional space, suggesting that INI1-Rpt1 domain structurally mimics TAR. This possible mimicry between INI1-Rpt1 and TAR explains the mechanism by which INI1/SMARCB1 influences HIV-1 late events and suggests additional strategies to inhibit HIV-1 replication.
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Affiliation(s)
- Updesh Dixit
- Department of Genetics, Albert Einstein College of Medicine, New York City, NY, USA
| | - Savita Bhutoria
- Department of Genetics, Albert Einstein College of Medicine, New York City, NY, USA
| | - Xuhong Wu
- Department of Genetics, Albert Einstein College of Medicine, New York City, NY, USA
| | - Liming Qiu
- Dalton Cardiovascular Research Center, Department of Physics and Astronomy, Department of Biochemistry, and Institute for Data Science and Informatics, University of Missouri, Columbia, MO, USA
| | - Menachem Spira
- Department of Genetics, Albert Einstein College of Medicine, New York City, NY, USA
| | - Sheeba Mathew
- Department of Genetics, Albert Einstein College of Medicine, New York City, NY, USA
| | - Richard Harris
- Department of Biochemistry, Albert Einstein College of Medicine, New York City, NY, USA
| | - Lucas J Adams
- Laboratory of Structural Biology Research, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Sean Cahill
- Department of Biochemistry, Albert Einstein College of Medicine, New York City, NY, USA
| | - Rajiv Pathak
- Department of Genetics, Albert Einstein College of Medicine, New York City, NY, USA
| | - P Rajesh Kumar
- Department of Biochemistry, Albert Einstein College of Medicine, New York City, NY, USA
| | - Minh Nguyen
- Department of Genetics, Albert Einstein College of Medicine, New York City, NY, USA
| | - Seetharama A Acharya
- Department of Anatomy & Structural Biology, Albert Einstein College of Medicine, New York, NY, USA
| | - Michael Brenowitz
- Department of Biochemistry, Albert Einstein College of Medicine, New York City, NY, USA
| | - Steven C Almo
- Department of Biochemistry, Albert Einstein College of Medicine, New York City, NY, USA
| | - Xiaoqin Zou
- Dalton Cardiovascular Research Center, Department of Physics and Astronomy, Department of Biochemistry, and Institute for Data Science and Informatics, University of Missouri, Columbia, MO, USA
| | - Alasdair C Steven
- Laboratory of Structural Biology Research, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD, USA
| | - David Cowburn
- Department of Biochemistry, Albert Einstein College of Medicine, New York City, NY, USA
| | - Mark Girvin
- Department of Biochemistry, Albert Einstein College of Medicine, New York City, NY, USA
| | - Ganjam V Kalpana
- Department of Genetics, Albert Einstein College of Medicine, New York City, NY, USA.
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41
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Ganser LR, Chu CC, Bogerd HP, Kelly ML, Cullen BR, Al-Hashimi HM. Probing RNA Conformational Equilibria within the Functional Cellular Context. Cell Rep 2021; 30:2472-2480.e4. [PMID: 32101729 DOI: 10.1016/j.celrep.2020.02.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 12/24/2019] [Accepted: 01/31/2020] [Indexed: 12/17/2022] Open
Abstract
Low-abundance short-lived non-native conformations referred to as excited states (ESs) are increasingly observed in vitro and implicated in the folding and biological activities of regulatory RNAs. We developed an approach for assessing the relative abundance of RNA ESs within the functional cellular context. Nuclear magnetic resonance (NMR) spectroscopy was used to estimate the degree to which substitution mutations bias conformational equilibria toward the inactive ES in vitro. The cellular activity of the ES-stabilizing mutants was used as an indirect measure of the conformational equilibria within the functional cellular context. Compensatory mutations that restore the ground-state conformation were used to control for changes in sequence. Using this approach, we show that the ESs of two regulatory RNAs from HIV-1, the transactivation response element (TAR) and the Rev response element (RRE), likely form in cells with abundances comparable to those measured in vitro, and their targeted stabilization may provide an avenue for developing anti-HIV therapeutics.
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Affiliation(s)
- Laura R Ganser
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
| | - Chia-Chieh Chu
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
| | - Hal P Bogerd
- Department of Molecular Genetics and Microbiology, Center for Virology, Duke University Medical Center, Durham, NC 27710, USA
| | - Megan L Kelly
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
| | - Bryan R Cullen
- Department of Molecular Genetics and Microbiology, Center for Virology, Duke University Medical Center, Durham, NC 27710, USA.
| | - Hashim M Al-Hashimi
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA.
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42
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Luo L, Chiu LY, Sugarman A, Gupta P, Rouskin S, Tolbert BS. HnRNP A1/A2 Proteins Assemble onto 7SK snRNA via Context Dependent Interactions. J Mol Biol 2021; 433:166885. [PMID: 33684393 DOI: 10.1016/j.jmb.2021.166885] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 02/13/2021] [Accepted: 02/15/2021] [Indexed: 02/08/2023]
Abstract
7SK small nuclear RNA (snRNA) is an abundant and ubiquitously expressed noncoding RNA that functions to modulate the activity of RNA Polymerase II (RNAPII) in part by stabilizing distinct pools of 7SK-protein complexes. Prevailing models suggest that the secondary structure of 7SK is dynamically remodeled within its alternative RNA-protein pools such that its architecture differentially regulates the exchange of cognate binding partners. The nuclear hnRNP A1/A2 proteins influence the biology of 7SK snRNA via processes that require an intact stem loop (SL) 3 domain; however, the molecular details by which hnRNPs assemble onto 7SK snRNA are yet to be described. Here, we have taken an integrated approach to present a detailed description of the 7SK-hnRNP A1 complex. We show that unbound 7SK snRNA adopts at least two major conformations in solution, with significant structural differences localizing to the SL2-3 linker and the base of SL3. Phylogenetic analysis indicates that this same region is the least genetically conserved feature of 7SK snRNA. By performing DMS modifications with the presence of excess protein, we reveal that hnRNP A1 binds with selectivity to SL3 through mechanisms that increase the flexibility of the RNA adjacent to putative binding sites. Calorimetric titrations further validate that hnRNP A1-SL3 assembly is complex with the affinity of discrete binding events modulated by the surrounding RNA structure. To interpret this context-dependent binding phenomenon, we determined a 3D model of SL3 to show that it folds to position minimal hnRNP A1/A2 binding sites (5'-Y/RAG-3') within different local environments. SL3-protein complexes resolved by SEC-MALS-SAXS confirm that up to four hnRNP A1 proteins bind along the entire surface of SL3 via interactions that preserve the overall structural integrity of this domain. In sum, the collective results presented here reveal a specific role for a folded SL3 domain to scaffold hnRNP A1/A2-7SK assembly via mechanisms modulated by the surrounding RNA structure.
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Affiliation(s)
- Le Luo
- Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106, United States
| | - Liang-Yuan Chiu
- Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106, United States
| | - Andrew Sugarman
- Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106, United States
| | - Paromita Gupta
- Whitehead Institute for Biomedical Research, Cambridge, MA, United States
| | - Silvi Rouskin
- Whitehead Institute for Biomedical Research, Cambridge, MA, United States
| | - Blanton S Tolbert
- Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106, United States.
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43
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Chavali SS, Mali SM, Jenkins JL, Fasan R, Wedekind JE. Co-crystal structures of HIV TAR RNA bound to lab-evolved proteins show key roles for arginine relevant to the design of cyclic peptide TAR inhibitors. J Biol Chem 2020; 295:16470-16486. [PMID: 33051202 PMCID: PMC7864049 DOI: 10.1074/jbc.ra120.015444] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 09/24/2020] [Indexed: 01/28/2023] Open
Abstract
RNA-protein interfaces control key replication events during the HIV-1 life cycle. The viral trans-activator of transcription (Tat) protein uses an archetypal arginine-rich motif (ARM) to recruit the host positive transcription elongation factor b (pTEFb) complex onto the viral trans-activation response (TAR) RNA, leading to activation of HIV transcription. Efforts to block this interaction have stimulated production of biologics designed to disrupt this essential RNA-protein interface. Here, we present four co-crystal structures of lab-evolved TAR-binding proteins (TBPs) in complex with HIV-1 TAR. Our results reveal that high-affinity binding requires a distinct sequence and spacing of arginines within a specific β2-β3 hairpin loop that arose during selection. Although loops with as many as five arginines were analyzed, only three arginines could bind simultaneously with major-groove guanines. Amino acids that promote backbone interactions within the β2-β3 loop were also observed to be important for high-affinity interactions. Based on structural and affinity analyses, we designed two cyclic peptide mimics of the TAR-binding β2-β3 loop sequences present in two high-affinity TBPs (KD values of 4.2 ± 0.3 and 3.0 ± 0.3 nm). Our efforts yielded low-molecular weight compounds that bind TAR with low micromolar affinity (KD values ranging from 3.6 to 22 μm). Significantly, one cyclic compound within this series blocked binding of the Tat-ARM peptide to TAR in solution assays, whereas its linear counterpart did not. Overall, this work provides insight into protein-mediated TAR recognition and lays the ground for the development of cyclic peptide inhibitors of a vital HIV-1 RNA-protein interaction.
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Affiliation(s)
- Sai Shashank Chavali
- Department of Biochemistry and Biophysics and Center for RNA Biology, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA
| | - Sachitanand M Mali
- Department of Chemistry, University of Rochester, Rochester, New York, USA
| | - Jermaine L Jenkins
- Department of Biochemistry and Biophysics and Center for RNA Biology, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA
| | - Rudi Fasan
- Department of Chemistry, University of Rochester, Rochester, New York, USA
| | - Joseph E Wedekind
- Department of Biochemistry and Biophysics and Center for RNA Biology, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA.
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44
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Depicting HIV-1 Transcriptional Mechanisms: A Summary of What We Know. Viruses 2020; 12:v12121385. [PMID: 33287435 PMCID: PMC7761857 DOI: 10.3390/v12121385] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 11/26/2020] [Accepted: 12/01/2020] [Indexed: 12/19/2022] Open
Abstract
Despite the introduction of combinatory antiretroviral therapy (cART), HIV-1 infection cannot be cured and is still one of the major health issues worldwide. Indeed, as soon as cART is interrupted, a rapid rebound of viremia is observed. The establishment of viral latency and the persistence of the virus in cellular reservoirs constitute the main barrier to HIV eradication. For this reason, new therapeutic approaches have emerged to purge or restrain the HIV-1 reservoirs in order to cure infected patients. However, the viral latency is a multifactorial process that depends on various cellular mechanisms. Since these new therapies mainly target viral transcription, their development requires a detailed and precise understanding of the regulatory mechanism underlying HIV-1 transcription. In this review, we discuss the complex molecular transcriptional network regulating HIV-1 gene expression by focusing on the involvement of host cell factors that could be used as potential drug targets to design new therapeutic strategies and, to a larger extent, to reach an HIV-1 functional cure.
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45
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Chavali SS, Cavender CE, Mathews DH, Wedekind JE. Arginine Forks Are a Widespread Motif to Recognize Phosphate Backbones and Guanine Nucleobases in the RNA Major Groove. J Am Chem Soc 2020; 142:19835-19839. [PMID: 33170672 DOI: 10.1021/jacs.0c09689] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
RNA recognition by proteins is central to biology. Here we demonstrate the existence of a recurrent structural motif, the "arginine fork", that codifies arginine readout of cognate backbone and guanine nucleobase interactions in a variety of protein-RNA complexes derived from viruses, metabolic enzymes, and ribosomes. Nearly 30 years ago, a theoretical arginine fork model was posited to account for the specificity between the HIV-1 Tat protein and TAR RNA. This model predicted that a single arginine should form four complementary contacts with nearby phosphates, yielding a two-pronged backbone readout. Recent high-resolution structures of TAR-protein complexes have unveiled new details, including (i) arginine interactions with the phosphate backbone and the major-groove edge of guanine and (ii) simultaneous cation-π contacts between the guanidinium group and flanking nucleobases. These findings prompted us to search for arginine forks within experimental protein-RNA structures retrieved from the Protein Data Bank. The results revealed four distinct classes of arginine forks that we have defined using a rigorous but flexible nomenclature. Examples are presented in the context of ribosomal and nonribosomal interfaces with analysis of arginine dihedral angles and structural (suite) classification of RNA targets. When arginine fork chemical recognition principles were applied to existing structures with unusual arginine-guanine recognition, we found that the arginine fork geometry was more consistent with the experimental data, suggesting the utility of fork classifications to improve structural models. Software to analyze arginine-RNA interactions has been made available to the community.
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Affiliation(s)
- Sai Shashank Chavali
- Department of Biochemistry & Biophysics and Center for RNA Biology, University of Rochester School of Medicine & Dentistry, 601 Elmwood Avenue, Rochester, New York 14642, United States
| | - Chapin E Cavender
- Department of Biochemistry & Biophysics and Center for RNA Biology, University of Rochester School of Medicine & Dentistry, 601 Elmwood Avenue, Rochester, New York 14642, United States
| | - David H Mathews
- Department of Biochemistry & Biophysics and Center for RNA Biology, University of Rochester School of Medicine & Dentistry, 601 Elmwood Avenue, Rochester, New York 14642, United States
| | - Joseph E Wedekind
- Department of Biochemistry & Biophysics and Center for RNA Biology, University of Rochester School of Medicine & Dentistry, 601 Elmwood Avenue, Rochester, New York 14642, United States
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46
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Advanced approaches for elucidating structures of large RNAs using NMR spectroscopy and complementary methods. Methods 2020; 183:93-107. [DOI: 10.1016/j.ymeth.2020.01.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 11/11/2019] [Accepted: 01/16/2020] [Indexed: 11/23/2022] Open
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47
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Boyd PS, Brown JB, Brown JD, Catazaro J, Chaudry I, Ding P, Dong X, Marchant J, O’Hern CT, Singh K, Swanson C, Summers MF, Yasin S. NMR Studies of Retroviral Genome Packaging. Viruses 2020; 12:v12101115. [PMID: 33008123 PMCID: PMC7599994 DOI: 10.3390/v12101115] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 09/18/2020] [Accepted: 09/26/2020] [Indexed: 12/03/2022] Open
Abstract
Nearly all retroviruses selectively package two copies of their unspliced RNA genomes from a cellular milieu that contains a substantial excess of non-viral and spliced viral RNAs. Over the past four decades, combinations of genetic experiments, phylogenetic analyses, nucleotide accessibility mapping, in silico RNA structure predictions, and biophysical experiments were employed to understand how retroviral genomes are selected for packaging. Genetic studies provided early clues regarding the protein and RNA elements required for packaging, and nucleotide accessibility mapping experiments provided insights into the secondary structures of functionally important elements in the genome. Three-dimensional structural determinants of packaging were primarily derived by nuclear magnetic resonance (NMR) spectroscopy. A key advantage of NMR, relative to other methods for determining biomolecular structure (such as X-ray crystallography), is that it is well suited for studies of conformationally dynamic and heterogeneous systems—a hallmark of the retrovirus packaging machinery. Here, we review advances in understanding of the structures, dynamics, and interactions of the proteins and RNA elements involved in retroviral genome selection and packaging that are facilitated by NMR.
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48
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Osmer PS, Singh G, Boris-Lawrie K. A New Approach to 3D Modeling of Inhomogeneous Populations of Viral Regulatory RNA. Viruses 2020; 12:v12101108. [PMID: 33003639 PMCID: PMC7650772 DOI: 10.3390/v12101108] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 09/24/2020] [Accepted: 09/27/2020] [Indexed: 12/17/2022] Open
Abstract
Tertiary structure (3D) is the physical context of RNA regulatory activity. Retroviruses are RNA viruses that replicate through the proviral DNA intermediate transcribed by hosts. Proviral transcripts form inhomogeneous populations due to variable structural ensembles of overlapping regulatory RNA motifs in the 5′-untranslated region (UTR), which drive RNAs to be spliced or translated, and/or dimerized and packaged into virions. Genetic studies and structural techniques have provided fundamental input constraints to begin predicting HIV 3D conformations in silico. Using SimRNA and sets of experimentally-determined input constraints of HIVNL4-3 trans-activation responsive sequence (TAR) and pairings of unique-5′ (U5) with dimerization (DIS) or AUG motifs, we calculated a series of 3D models that differ in proximity of 5′-Cap and the junction of TAR and PolyA helices; configuration of primer binding site (PBS)-segment; and two host cofactors binding sites. Input constraints on U5-AUG pairings were most compatible with intramolecular folding of 5′-UTR motifs in energetic minima. Introducing theoretical constraints predicted metastable PolyA region drives orientation of 5′-Cap with TAR, U5 and PBS-segment helices. SimRNA and the workflow developed herein provides viable options to predict 3D conformations of inhomogeneous populations of large RNAs that have been intractable to conventional ensemble methods.
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Affiliation(s)
- Patrick S. Osmer
- Department of Astronomy, The Ohio State University, Columbus, OH 43210, USA;
| | - Gatikrushna Singh
- Department of Veterinary and Biomedical Sciences, University of Minnesota, Saint Paul, MN 55108, USA;
| | - Kathleen Boris-Lawrie
- Department of Veterinary and Biomedical Sciences, University of Minnesota, Saint Paul, MN 55108, USA;
- Correspondence: ; Tel.: +1-612-625-2100
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Brillet K, Martinez-Zapien D, Bec G, Ennifar E, Dock-Bregeon AC, Lebars I. Different views of the dynamic landscape covered by the 5'-hairpin of the 7SK small nuclear RNA. RNA (NEW YORK, N.Y.) 2020; 26:1184-1197. [PMID: 32430362 PMCID: PMC7430674 DOI: 10.1261/rna.074955.120] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 05/13/2020] [Indexed: 06/11/2023]
Abstract
The 7SK small nuclear RNA (7SKsnRNA) plays a key role in the regulation of RNA polymerase II by sequestrating and inhibiting the positive transcription elongation factor b (P-TEFb) in the 7SK ribonucleoprotein complex (7SKsnRNP), a process mediated by interaction with the protein HEXIM. P-TEFb is also an essential cellular factor recruited by the viral protein Tat to ensure the replication of the viral RNA in the infection cycle of the human immunodeficiency virus (HIV-1). Tat promotes the release of P-TEFb from the 7SKsnRNP and subsequent activation of transcription, by displacing HEXIM from the 5'-hairpin of the 7SKsnRNA. This hairpin (HP1), comprising the signature sequence of the 7SKsnRNA, has been the subject of three independent structural studies aimed at identifying the structural features that could drive the recognition by the two proteins, both depending on arginine-rich motifs (ARM). Interestingly, four distinct structures were determined. In an attempt to provide a comprehensive view of the structure-function relationship of this versatile RNA, we present here a structural analysis of the models, highlighting how HP1 is able to adopt distinct conformations with significant impact on the compactness of the molecule. Since these models are solved under different conditions by nuclear magnetic resonance (NMR) and crystallography, the impact of the buffer composition on the conformational variation was investigated by complementary biophysical approaches. Finally, using isothermal titration calorimetry, we determined the thermodynamic signatures of the Tat-ARM and HEXIM-ARM peptide interactions with the RNA, showing that they are associated with distinct binding mechanisms.
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Affiliation(s)
- Karl Brillet
- Université de Strasbourg, Architecture et Réactivité de l'ARN - CNRS UPR 9002, Institut de Biologie Moléculaire et Cellulaire, F-67084 Strasbourg, France
| | - Denise Martinez-Zapien
- Department of Integrated Structural Biology, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), CNRS UMR 7104, INSERM U964, Université de Strasbourg, 67404 Illkirch Cedex, France
| | - Guillaume Bec
- Université de Strasbourg, Architecture et Réactivité de l'ARN - CNRS UPR 9002, Institut de Biologie Moléculaire et Cellulaire, F-67084 Strasbourg, France
| | - Eric Ennifar
- Université de Strasbourg, Architecture et Réactivité de l'ARN - CNRS UPR 9002, Institut de Biologie Moléculaire et Cellulaire, F-67084 Strasbourg, France
| | - Anne-Catherine Dock-Bregeon
- Laboratory of Integrative Biology of Marine Models (LBI2M), Sorbonne University-CNRS UMR 8227, Station Biologique de Roscoff, 29680 Roscoff Cedex, France
| | - Isabelle Lebars
- Université de Strasbourg, Architecture et Réactivité de l'ARN - CNRS UPR 9002, Institut de Biologie Moléculaire et Cellulaire, F-67084 Strasbourg, France
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Brown JA. Unraveling the structure and biological functions of RNA triple helices. WILEY INTERDISCIPLINARY REVIEWS-RNA 2020; 11:e1598. [PMID: 32441456 PMCID: PMC7583470 DOI: 10.1002/wrna.1598] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Revised: 04/06/2020] [Accepted: 04/15/2020] [Indexed: 02/06/2023]
Abstract
It has been nearly 63 years since the first characterization of an RNA triple helix in vitro by Gary Felsenfeld, David Davies, and Alexander Rich. An RNA triple helix consists of three strands: A Watson–Crick RNA double helix whose major‐groove establishes hydrogen bonds with the so‐called “third strand”. In the past 15 years, it has been recognized that these major‐groove RNA triple helices, like single‐stranded and double‐stranded RNA, also mediate prominent biological roles inside cells. Thus far, these triple helices are known to mediate catalysis during telomere synthesis and RNA splicing, bind to ligands and ions so that metabolite‐sensing riboswitches can regulate gene expression, and provide a clever strategy to protect the 3′ end of RNA from degradation. Because RNA triple helices play important roles in biology, there is a renewed interest in better understanding the fundamental properties of RNA triple helices and developing methods for their high‐throughput discovery. This review provides an overview of the fundamental biochemical and structural properties of major‐groove RNA triple helices, summarizes the structure and function of naturally occurring RNA triple helices, and describes prospective strategies to isolate RNA triple helices as a means to establish the “triplexome”. This article is categorized under:RNA Structure and Dynamics > RNA Structure and Dynamics RNA Structure and Dynamics > RNA Structure, Dynamics and Chemistry RNA Structure and Dynamics > Influence of RNA Structure in Biological Systems
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Affiliation(s)
- Jessica A Brown
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
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