1
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Zhao H, Syed AM, Khalid MM, Nguyen A, Ciling A, Wu D, Yau WM, Srinivasan S, Esposito D, Doudna J, Piszczek G, Ott M, Schuck P. Assembly of SARS-CoV-2 nucleocapsid protein with nucleic acid. Nucleic Acids Res 2024; 52:6647-6661. [PMID: 38587193 PMCID: PMC11194069 DOI: 10.1093/nar/gkae256] [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: 11/22/2023] [Revised: 03/18/2024] [Accepted: 03/27/2024] [Indexed: 04/09/2024] Open
Abstract
The viral genome of SARS-CoV-2 is packaged by the nucleocapsid (N-)protein into ribonucleoprotein particles (RNPs), 38 ± 10 of which are contained in each virion. Their architecture has remained unclear due to the pleomorphism of RNPs, the high flexibility of N-protein intrinsically disordered regions, and highly multivalent interactions between viral RNA and N-protein binding sites in both N-terminal (NTD) and C-terminal domain (CTD). Here we explore critical interaction motifs of RNPs by applying a combination of biophysical techniques to ancestral and mutant proteins binding different nucleic acids in an in vitro assay for RNP formation, and by examining nucleocapsid protein variants in a viral assembly assay. We find that nucleic acid-bound N-protein dimers oligomerize via a recently described protein-protein interface presented by a transient helix in its long disordered linker region between NTD and CTD. The resulting hexameric complexes are stabilized by multivalent protein-nucleic acid interactions that establish crosslinks between dimeric subunits. Assemblies are stabilized by the dimeric CTD of N-protein offering more than one binding site for stem-loop RNA. Our study suggests a model for RNP assembly where N-protein scaffolding at high density on viral RNA is followed by cooperative multimerization through protein-protein interactions in the disordered linker.
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Affiliation(s)
- Huaying Zhao
- Laboratory of Dynamics of Macromolecular Assembly, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892, USA
| | - Abdullah M Syed
- Gladstone Institutes, San Francisco, CA 94158, USA
- Innovative Genomics Institute, University of California, Berkeley, CA 94720, USA
| | - Mir M Khalid
- Gladstone Institutes, San Francisco, CA 94158, USA
| | - Ai Nguyen
- Laboratory of Dynamics of Macromolecular Assembly, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892, USA
| | - Alison Ciling
- Gladstone Institutes, San Francisco, CA 94158, USA
- Innovative Genomics Institute, University of California, Berkeley, CA 94720, USA
| | - Di Wu
- Biophysics Core Facility, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Wai-Ming Yau
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Sanjana Srinivasan
- Laboratory of Dynamics of Macromolecular Assembly, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892, USA
| | - Dominic Esposito
- Protein Expression Laboratory, Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA
| | - Jennifer A Doudna
- Gladstone Institutes, San Francisco, CA 94158, USA
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
- HHMI, University of California, Berkeley, CA 94720, USA
- Department of Chemistry, University of California, Berkeley, CA 94720, USA
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA 94720, USA
| | - Grzegorz Piszczek
- Biophysics Core Facility, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Melanie Ott
- Gladstone Institutes, San Francisco, CA 94158, USA
- Department of Medicine, University of California, San Francisco, CA 94143, USA
- Chan Zuckerberg Biohub, San Francisco, CA 94158, USA
| | - Peter Schuck
- Laboratory of Dynamics of Macromolecular Assembly, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892, USA
- Center for Biomedical Engineering Technology Acceleration, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892, USA
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2
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Brudenell EL, Pohare MB, Zafred D, Phipps J, Hornsby HR, Darby JF, Dai J, Liggett E, Cain KM, Barran PE, de Silva TI, Sayers JR. Efficient overexpression and purification of severe acute respiratory syndrome coronavirus 2 nucleocapsid proteins in Escherichia coli. Biochem J 2024; 481:669-682. [PMID: 38713013 DOI: 10.1042/bcj20240019] [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: 01/22/2024] [Revised: 04/30/2024] [Accepted: 05/07/2024] [Indexed: 05/08/2024]
Abstract
The fundamental biology of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleocapsid protein (Ncap), its use in diagnostic assays and its potential application as a vaccine component have received considerable attention since the outbreak of the Covid19 pandemic in late 2019. Here we report the scalable expression and purification of soluble, immunologically active, SARS-CoV-2 Ncap in Escherichia coli. Codon-optimised synthetic genes encoding the original Ncap sequence and four common variants with an N-terminal 6His affinity tag (sequence MHHHHHHG) were cloned into an inducible expression vector carrying a regulated bacteriophage T5 synthetic promoter controlled by lac operator binding sites. The constructs were used to express Ncap proteins and protocols developed which allow efficient production of purified Ncap with yields of over 200 mg per litre of culture media. These proteins were deployed in ELISA assays to allow comparison of their responses to human sera. Our results suggest that there was no detectable difference between the 6His-tagged and untagged original Ncap proteins but there may be a slight loss of sensitivity of sera to other Ncap isolates.
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Affiliation(s)
- Emma L Brudenell
- Sheffield Institute for Nucleic Acids and Florey Institute, Section of Infection and Immunity, Division of Clinical Medicine, School of Medicine and Population Health, The University of Sheffield, Beech Hill Road, Sheffield S10 2RX, U.K
| | - Manoj B Pohare
- Sheffield Institute for Nucleic Acids and Florey Institute, Section of Infection and Immunity, Division of Clinical Medicine, School of Medicine and Population Health, The University of Sheffield, Beech Hill Road, Sheffield S10 2RX, U.K
| | - Domen Zafred
- Sheffield Institute for Nucleic Acids and Florey Institute, Section of Infection and Immunity, Division of Clinical Medicine, School of Medicine and Population Health, The University of Sheffield, Beech Hill Road, Sheffield S10 2RX, U.K
| | - Janine Phipps
- Sheffield Institute for Nucleic Acids and Florey Institute, Section of Infection and Immunity, Division of Clinical Medicine, School of Medicine and Population Health, The University of Sheffield, Beech Hill Road, Sheffield S10 2RX, U.K
| | - Hailey R Hornsby
- Sheffield Institute for Nucleic Acids and Florey Institute, Section of Infection and Immunity, Division of Clinical Medicine, School of Medicine and Population Health, The University of Sheffield, Beech Hill Road, Sheffield S10 2RX, U.K
| | - John F Darby
- Sheffield Institute for Nucleic Acids and Florey Institute, Section of Infection and Immunity, Division of Clinical Medicine, School of Medicine and Population Health, The University of Sheffield, Beech Hill Road, Sheffield S10 2RX, U.K
| | - Junxiao Dai
- Michael Barber Centre for Collaborative Mass Spectrometry, Department of Chemistry, Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, UK
| | - Ellen Liggett
- Michael Barber Centre for Collaborative Mass Spectrometry, Department of Chemistry, Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, UK
| | - Kathleen M Cain
- Michael Barber Centre for Collaborative Mass Spectrometry, Department of Chemistry, Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, UK
| | - Perdita E Barran
- Michael Barber Centre for Collaborative Mass Spectrometry, Department of Chemistry, Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, UK
| | - Thushan I de Silva
- Sheffield Institute for Nucleic Acids and Florey Institute, Section of Infection and Immunity, Division of Clinical Medicine, School of Medicine and Population Health, The University of Sheffield, Beech Hill Road, Sheffield S10 2RX, U.K
| | - Jon R Sayers
- Sheffield Institute for Nucleic Acids and Florey Institute, Section of Infection and Immunity, Division of Clinical Medicine, School of Medicine and Population Health, The University of Sheffield, Beech Hill Road, Sheffield S10 2RX, U.K
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3
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Stuwe H, Reardon PN, Yu Z, Shah S, Hughes K, Barbar EJ. Phosphorylation in the Ser/Arg-rich region of the nucleocapsid of SARS-CoV-2 regulates phase separation by inhibiting self-association of a distant helix. J Biol Chem 2024; 300:107354. [PMID: 38718862 PMCID: PMC11180338 DOI: 10.1016/j.jbc.2024.107354] [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: 04/01/2024] [Revised: 04/24/2024] [Accepted: 04/30/2024] [Indexed: 06/06/2024] Open
Abstract
The nucleocapsid protein (N) of SARS-CoV-2 is essential for virus replication, genome packaging, evading host immunity, and virus maturation. N is a multidomain protein composed of an independently folded monomeric N-terminal domain that is the primary site for RNA binding and a dimeric C-terminal domain that is essential for efficient phase separation and condensate formation with RNA. The domains are separated by a disordered Ser/Arg-rich region preceding a self-associating Leu-rich helix. Phosphorylation in the Ser/Arg region in infected cells decreases the viscosity of N:RNA condensates promoting viral replication and host immune evasion. The molecular level effect of phosphorylation, however, is missing from our current understanding. Using NMR spectroscopy and analytical ultracentrifugation, we show that phosphorylation destabilizes the self-associating Leu-rich helix 30 amino-acids distant from the phosphorylation site. NMR and gel shift assays demonstrate that RNA binding by the linker is dampened by phosphorylation, whereas RNA binding to the full-length protein is not significantly affected presumably due to retained strong interactions with the primary RNA-binding domain. Introducing a switchable self-associating domain to replace the Leu-rich helix confirms the importance of linker self-association to droplet formation and suggests that phosphorylation not only increases solubility of the positively charged elongated Ser/Arg region as observed in other RNA-binding proteins but can also inhibit self-association of the Leu-rich helix. These data highlight the effect of phosphorylation both at local sites and at a distant self-associating hydrophobic helix in regulating liquid-liquid phase separation of the entire protein.
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Affiliation(s)
- Hannah Stuwe
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon, USA
| | | | - Zhen Yu
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon, USA
| | - Sahana Shah
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon, USA
| | - Kaitlyn Hughes
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon, USA
| | - Elisar J Barbar
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon, USA.
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4
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Gien H, Morse M, McCauley MJ, Rouzina I, Gorelick RJ, Williams MC. Cationic Residues of the HIV-1 Nucleocapsid Protein Enable DNA Condensation to Maintain Viral Core Particle Stability during Reverse Transcription. Viruses 2024; 16:872. [PMID: 38932164 PMCID: PMC11209390 DOI: 10.3390/v16060872] [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: 03/29/2024] [Revised: 04/30/2024] [Accepted: 05/23/2024] [Indexed: 06/28/2024] Open
Abstract
The HIV-1 nucleocapsid protein (NC) is a multifunctional viral protein necessary for HIV-1 replication. Recent studies have demonstrated that reverse transcription (RT) completes in the intact viral capsid, and the timing of RT and uncoating are correlated. How the small viral core stably contains the ~10 kbp double stranded (ds) DNA product of RT, and the role of NC in this process, are not well understood. We showed previously that NC binds and saturates dsDNA in a non-specific electrostatic binding mode that triggers uniform DNA self-attraction, condensing dsDNA into a tight globule against extending forces up to 10 pN. In this study, we use optical tweezers and atomic force microscopy to characterize the role of NC's basic residues in dsDNA condensation. Basic residue mutations of NC lead to defective interaction with the dsDNA substrate, with the constant force plateau condensation observed with wild-type (WT) NC missing or diminished. These results suggest that NC's high positive charge is essential to its dsDNA condensing activity, and electrostatic interactions involving NC's basic residues are responsible in large part for the conformation, size, and stability of the dsDNA-protein complex inside the viral core. We observe DNA re-solubilization and charge reversal in the presence of excess NC, consistent with the electrostatic nature of NC-induced DNA condensation. Previous studies of HIV-1 replication in the presence of the same cationic residue mutations in NC showed significant defects in both single- and multiple-round viral infectivity. Although NC participates in many stages of viral replication, our results are consistent with the hypothesis that cationic residue mutations inhibit genomic DNA condensation, resulting in increased premature capsid uncoating and contributing to viral replication defects.
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Affiliation(s)
- Helena Gien
- Department of Physics, Northeastern University, Boston, MA 02115, USA; (H.G.); (M.M.); (M.J.M.)
| | - Michael Morse
- Department of Physics, Northeastern University, Boston, MA 02115, USA; (H.G.); (M.M.); (M.J.M.)
| | - Micah J. McCauley
- Department of Physics, Northeastern University, Boston, MA 02115, USA; (H.G.); (M.M.); (M.J.M.)
| | - Ioulia Rouzina
- Department of Chemistry and Biochemistry, Center for Retroviral Research and Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA;
| | - Robert J. Gorelick
- AIDS and Cancer Virus Program, Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA;
| | - Mark C. Williams
- Department of Physics, Northeastern University, Boston, MA 02115, USA; (H.G.); (M.M.); (M.J.M.)
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5
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Cashen BA, Morse M, Rouzina I, Karpel RL, Williams MC. C-terminal Domain of T4 gene 32 Protein Enables Rapid Filament Reorganization and Dissociation. J Mol Biol 2024; 436:168544. [PMID: 38508303 DOI: 10.1016/j.jmb.2024.168544] [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: 01/19/2024] [Revised: 02/27/2024] [Accepted: 03/14/2024] [Indexed: 03/22/2024]
Abstract
Bacteriophage T4 gene 32 protein (gp32) is a single-stranded DNA (ssDNA) binding protein essential for DNA replication. gp32 forms stable protein filaments on ssDNA through cooperative interactions between its core and N-terminal domain. gp32's C-terminal domain (CTD) is believed to primarily help coordinate DNA replication via direct interactions with constituents of the replisome. However, the exact mechanisms of these interactions are not known, and it is unclear how tightly-bound gp32 filaments are readily displaced from ssDNA as required for genomic processing. Here, we utilized truncated gp32 variants to demonstrate a key role of the CTD in regulating gp32 dissociation. Using optical tweezers, we probed the binding and dissociation dynamics of CTD-truncated gp32, *I, to an 8.1 knt ssDNA molecule and compared these measurements with those for full-length gp32. The *I-ssDNA helical filament becomes progressively unwound with increased protein concentration but remains significantly more stable than that of full-length, wild-type gp32. Protein oversaturation, concomitant with filament unwinding, facilitates rapid dissociation of full-length gp32 from across the entire ssDNA segment. In contrast, *I primarily unbinds slowly from only the ends of the cooperative clusters, regardless of the protein density and degree of DNA unwinding. Our results suggest that the CTD may constrain the relative twist angle of proteins within the ssDNA filament such that upon critical unwinding the cooperative interprotein interactions largely vanish, facilitating prompt removal of gp32. We propose a model of CTD-mediated gp32 displacement via internal restructuring of its filament, providing a mechanism for rapid ssDNA clearing during genomic processing.
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Affiliation(s)
- Ben A Cashen
- Department of Physics, Northeastern University, 360 Huntington Avenue, Boston, MA 02115, USA
| | - Michael Morse
- Department of Physics, Northeastern University, 360 Huntington Avenue, Boston, MA 02115, USA
| | - Ioulia Rouzina
- Department of Chemistry and Biochemistry, Center for Retroviral Research and Center for RNA Biology, Ohio State University, 281 W Lane Avenue, Columbus, OH 43210, USA
| | - Richard L Karpel
- Department of Chemistry and Biochemistry, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA
| | - Mark C Williams
- Department of Physics, Northeastern University, 360 Huntington Avenue, Boston, MA 02115, USA.
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6
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Laughlin PM, Young K, Gonzalez-Gutierrez G, Wang JC, Zlotnick A. A narrow ratio of nucleic acid to SARS-CoV-2 N-protein enables phase separation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.10.588883. [PMID: 38645044 PMCID: PMC11030382 DOI: 10.1101/2024.04.10.588883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/23/2024]
Abstract
SARS-CoV-2 Nucleocapsid protein (N) is a viral structural protein that packages the 30kb genomic RNA inside virions and forms condensates within infected cells through liquid-liquid phase separation (LLPS). N, in both soluble and condensed forms, has accessory roles in the viral life cycle including genome replication and immunosuppression. The ability to perform these tasks depends on phase separation and its reversibility. The conditions that stabilize and destabilize N condensates and the role of N-N interactions are poorly understood. We have investigated LLPS formation and dissolution in a minimalist system comprised of N protein and an ssDNA oligomer just long enough to support assembly. The short oligo allows us to focus on the role of N-N interaction. We have developed a sensitive FRET assay to interrogate LLPS assembly reactions from the perspective of the oligonucleotide. We find that N alone can form oligomers but that oligonucleotide enables their assembly into a three-dimensional phase. At a ~1:1 ratio of N to oligonucleotide LLPS formation is maximal. We find that a modest excess of N or of nucleic acid causes the LLPS to break down catastrophically. Under the conditions examined here assembly has a critical concentration of about 1 μM. The responsiveness of N condensates to their environment may have biological consequences. A better understanding of how nucleic acid modulates N-N association will shed light on condensate activity and could inform antiviral strategies targeting LLPS.
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Affiliation(s)
| | - Kimberly Young
- Department of Molecular and Cellular Biochemistry, Indiana University
| | | | - Joseph C.Y. Wang
- Department of Microbiology and Immunology, Pennsylvania State University College of Medicine
| | - Adam Zlotnick
- Department of Molecular and Cellular Biochemistry, Indiana University
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7
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Xu Z, Peng Q, Song J, Zhang H, Wei D, Demongeot J, Zeng Q. Bioinformatic analysis of defective viral genomes in SARS-CoV-2 and its impact on population infection characteristics. Front Immunol 2024; 15:1341906. [PMID: 38348041 PMCID: PMC10859446 DOI: 10.3389/fimmu.2024.1341906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 01/12/2024] [Indexed: 02/15/2024] Open
Abstract
DVGs (Defective Viral Genomes) are prevalent in RNA virus infections. In this investigation, we conducted an analysis of high-throughput sequencing data and observed widespread presence of DVGs in SARS-CoV-2. Comparative analysis between SARS-CoV-2 and diverse DNA viruses revealed heightened susceptibility to damage and increased sequencing sample heterogeneity within the SARS-CoV-2 genome. Whole-genome sequencing depth variability analysis exhibited a higher coefficient of variation for SARS-CoV-2, while DVG analysis indicated a significant proportion of recombination sites, signifying notable genome heterogeneity and suggesting that a large proportion of assembled virus particles contain incomplete RNA sequences. Moreover, our investigation explored the sequencing depth and DVG content differences among various strains. Our findings revealed that as the virus evolves, there is a notable increase in the proportion of intact genomes within virus particles, as evidenced by third-generation sequencing data. Specifically, the proportion of intact genome in the Omicron strain surpassed that of the Delta and Alpha strains. This observation effectively elucidates the heightened infectiousness of the Omicron strain compared to the Delta and Alpha strains. We also postulate that this improvement in completeness stems from enhanced virus assembly capacity, as the Omicron strain can promptly facilitate the binding of RNA and capsid protein, thereby reducing the exposure time of vulnerable virus RNA in the host environment and significantly mitigating its degradation. Finally, employing mathematical modeling, we simulated the impact of DVG effects under varying environmental factors on infection characteristics and population evolution. Our findings provide an explanation for the close association between symptom severity and the extent of virus invasion, as well as the substantial disparity in population infection characteristics caused by the same strain under distinct environmental conditions. This study presents a novel approach for future virus research and vaccine development.
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Affiliation(s)
- Zhaobin Xu
- Department of Life Science, Dezhou University, Dezhou, China
| | - Qingzhi Peng
- Department of Life Science, Dezhou University, Dezhou, China
| | - Jian Song
- Department of Life Science, Dezhou University, Dezhou, China
| | - Hongmei Zhang
- Department of Life Science, Dezhou University, Dezhou, China
| | - Dongqing Wei
- State Key Laboratory of Microbial Metabolism, Shanghai-Islamabad-Belgrade Joint Innovation Center on Antibacterial Resistances, Shanghai Jiao Tong University, Shanghai, China
- Joint International Research Laboratory of Metabolic & Developmental Sciences and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
- Zhongjing Research and Industrialization Institute of Chinese Medicine, Zhongguancun Scientific Park, Meixi, Nanyang, Henan, China
- Peng Cheng National Laboratory, Shenzhen, Guangdong, China
| | - Jacques Demongeot
- Laboratory AGEIS EA 7407, Team Tools for e-Gnosis Medical, Faculty of Medicine, University Grenoble Alpes (UGA), F-38700 La Tronche, France
| | - Qiangcheng Zeng
- Department of Life Science, Dezhou University, Dezhou, China
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8
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Zhang S, Wang J, Liu X, Kan Z, Zhang Y, Niu Z, Hu X, Zhang L, Zhang X, Song Z. Pemetrexed alleviates piglet diarrhea by blocking the interaction between porcine epidemic diarrhea virus nucleocapsid protein and Ezrin. J Virol 2024; 98:e0162523. [PMID: 38084960 PMCID: PMC10804979 DOI: 10.1128/jvi.01625-23] [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: 11/15/2023] [Accepted: 11/27/2023] [Indexed: 01/24/2024] Open
Abstract
Porcine epidemic diarrhea virus (PEDV) is an enteric coronavirus that causes high mortality in piglets, thus posing a serious threat to the world pig industry. Porcine epidemic diarrhea (PED) is related to the imbalance of sodium absorption by small intestinal epithelial cells; however, the etiology of sodium imbalanced diarrhea caused by PEDV remains unclear. Herein, we first proved that PEDV can cause a significant decrease in Na+/H+ exchanger 3 (NHE3) expression on the cell membrane, in a viral dose-dependent manner. Further study showed that the PEDV nucleocapsid (N) protein participates in the regulation of NHE3 activity through interacting with Ezrin. Flame atomic absorption spectroscopy results indicated a serious imbalance in Na+ concentration inside and outside cells following overexpression of PEDV N. Meanwhile, molecular docking technology identified that the small molecule drug Pemetrexed acts on the PEDV N-Ezrin interaction region. It was confirmed that Pemetrexed can alleviate the imbalanced Na+ concentration in IPEC-J2 cells and the diarrhea symptoms of Rongchang pigs caused by PEDV infection. Overall, our data suggest that the interaction between PEDV N and Ezrin reduces the level of phosphorylated Ezrin, resulting in a decrease in the amount of NHE3 protein on the cell membrane. This leads to an imbalance of intracellular and extracellular Na+, which causes diarrhea symptoms in piglets. Pemetrexed is effective in relieving diarrhea caused by PEDV. Our results provide a reference to screen for anti-PEDV targets and to develop drugs to prevent PED.IMPORTANCEPorcine epidemic diarrhea (PED) has caused significant economic losses to the pig industry since its initial outbreak, and the pathogenic mechanism of porcine epidemic diarrhea virus (PEDV) is still under investigation. Herein, we found that the PEDV nucleocapsid protein interacts with Ezrin to regulate Na+/H+ exchanger 3 activity. In addition, we screened out Pemetrexed, a small molecule drug, which can effectively alleviate pig diarrhea caused by PEDV. These results provide support for further exploration of the pathogenesis of PEDV and the development of drugs to prevent PED.
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Affiliation(s)
- Shujuan Zhang
- College of Veterinary Medicine, Southwest University, Chongqing, China
| | - Jing Wang
- College of Veterinary Medicine, Southwest University, Chongqing, China
| | - Xiangyang Liu
- College of Veterinary Medicine, Southwest University, Chongqing, China
- College of Veterinary Medicine, Xinjiang Agricultural University, Ürümqi, China
| | - Zifei Kan
- College of Veterinary Medicine, Southwest University, Chongqing, China
- School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Yiling Zhang
- College of Veterinary Medicine, Southwest University, Chongqing, China
- College of Animal Science and Technology, Chongqing Three Gorges Vocational College, Chongqing, China
| | - Zheng Niu
- College of Veterinary Medicine, Southwest University, Chongqing, China
- College of Veterinary Medicine, Northwest A and F University, Shanxi, China
| | - Xia Hu
- College of Veterinary Medicine, Southwest University, Chongqing, China
| | - Li Zhang
- College of Veterinary Medicine, Southwest University, Chongqing, China
| | - Xingcui Zhang
- College of Veterinary Medicine, Southwest University, Chongqing, China
- Immunology Research Center, Medical Research Institute, Southwest University, Chongqing, China
| | - Zhenhui Song
- College of Veterinary Medicine, Southwest University, Chongqing, China
- Immunology Research Center, Medical Research Institute, Southwest University, Chongqing, China
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9
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Sundar Rajan V, Wypijewska Del Nogal A, Levin S, Wilhelmsson LM, Westerlund F. Exploring the conformational dynamics of the SARS-CoV-2 SL4 hairpin by combining optical tweezers and base analogues. NANOSCALE 2024; 16:752-764. [PMID: 38087988 PMCID: PMC10763987 DOI: 10.1039/d3nr04110g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 12/06/2023] [Indexed: 01/04/2024]
Abstract
The parasitic nature of the SARS-CoV-2 virus demands selective packaging of its RNA genome (gRNA) from the abundance of other nucleic acids present in infected cells. Despite increasing evidence that stem-loop 4 (SL4) of the gRNA 5' UTR is involved in the initiation of this process by binding the nucleocapsid (N) protein, little is known about its conformational dynamics. Here, we unravel the stability, dynamics and (un)folding pathways of SL4 using optical tweezers and a base analogue, tCO, that provides a local and subtle increase in base stacking without perturbing hydrogen bonding. We find that SL4 (un)folds mainly in a single step or through an intermediate, encompassing nucleotides from the central U bulge to the hairpin loop. Due to an upper-stem CU mismatch, SL4 is prone to misfold, the extent of which can be tuned by incorporating tCO at different positions. Our study contributes to a better understanding of SARS-CoV-2 packaging and the design of drugs targeting SL4. We also highlight the generalizability of using base analogues in optical tweezers experiments for probing intramolecular states and conformational transitions of various nucleic acids at the level of single molecules and with base-pair resolution.
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Affiliation(s)
- Vinoth Sundar Rajan
- Division of Chemical Biology, Department of Life Sciences, Chalmers University of Technology, Gothenburg, SE-412 96, Sweden.
- Division of Chemistry and Biochemistry, Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Gothenburg, SE-412 96, Sweden.
| | - Anna Wypijewska Del Nogal
- Division of Chemistry and Biochemistry, Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Gothenburg, SE-412 96, Sweden.
| | - Sune Levin
- Division of Chemical Biology, Department of Life Sciences, Chalmers University of Technology, Gothenburg, SE-412 96, Sweden.
| | - L Marcus Wilhelmsson
- Division of Chemistry and Biochemistry, Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Gothenburg, SE-412 96, Sweden.
| | - Fredrik Westerlund
- Division of Chemical Biology, Department of Life Sciences, Chalmers University of Technology, Gothenburg, SE-412 96, Sweden.
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10
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Zhao H, Syed AM, Khalid MM, Nguyen A, Ciling A, Wu D, Yau WM, Srinivasan S, Esposito D, Doudna JA, Piszczek G, Ott M, Schuck P. Assembly reactions of SARS-CoV-2 nucleocapsid protein with nucleic acid. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.22.568361. [PMID: 38045338 PMCID: PMC10690241 DOI: 10.1101/2023.11.22.568361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
The viral genome of SARS-CoV-2 is packaged by the nucleocapsid (N-) protein into ribonucleoprotein particles (RNPs), 38±10 of which are contained in each virion. Their architecture has remained unclear due to the pleomorphism of RNPs, the high flexibility of N-protein intrinsically disordered regions, and highly multivalent interactions between viral RNA and N-protein binding sites in both N-terminal (NTD) and C-terminal domain (CTD). Here we explore critical interaction motifs of RNPs by applying a combination of biophysical techniques to mutant proteins binding different nucleic acids in an in vitro assay for RNP formation, and by examining mutant proteins in a viral assembly assay. We find that nucleic acid-bound N-protein dimers oligomerize via a recently described protein-protein interface presented by a transient helix in its long disordered linker region between NTD and CTD. The resulting hexameric complexes are stabilized by multi-valent protein-nucleic acid interactions that establish crosslinks between dimeric subunits. Assemblies are stabilized by the dimeric CTD of N-protein offering more than one binding site for stem-loop RNA. Our study suggests a model for RNP assembly where N-protein scaffolding at high density on viral RNA is followed by cooperative multimerization through protein-protein interactions in the disordered linker.
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Affiliation(s)
- Huaying Zhao
- Laboratory of Dynamics of Macromolecular Assembly, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892
| | - Abdullah M. Syed
- Gladstone Institutes, San Francisco, CA 94158
- Innovative Genomics Institute, University of California, Berkeley, CA 94720
| | | | - Ai Nguyen
- Laboratory of Dynamics of Macromolecular Assembly, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892
| | - Alison Ciling
- Gladstone Institutes, San Francisco, CA 94158
- Innovative Genomics Institute, University of California, Berkeley, CA 94720
| | - Di Wu
- Biophysics Core Facility, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Wai-Ming Yau
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Sanjana Srinivasan
- Laboratory of Dynamics of Macromolecular Assembly, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892
| | - Dominic Esposito
- Protein Expression Laboratory, Frederick National Laboratory for Cancer Research, Frederick, MD 21702
| | - Jennifer A. Doudna
- Gladstone Institutes, San Francisco, CA 94158
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
- HHMI, University of California, Berkeley, CA 94720
- Department of Chemistry, University of California, Berkeley, CA 94720
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA 94720
| | - Grzegorz Piszczek
- Biophysics Core Facility, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Melanie Ott
- Gladstone Institutes, San Francisco, CA 94158
- Department of Medicine, University of California, San Francisco, CA 94143
- Chan Zuckerberg Biohub, San Francisco, CA 94158
| | - Peter Schuck
- Laboratory of Dynamics of Macromolecular Assembly, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892
- Center for Biomedical Engineering Technology Acceleration, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892
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11
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Cunningham CL, Frye CJ, Makowski JA, Kensinger AH, Shine M, Milback EJ, Lackey PE, Evanseck JD, Mihailescu MR. Effect of the SARS-CoV-2 Delta-associated G15U mutation on the s2m element dimerization and its interactions with miR-1307-3p. RNA (NEW YORK, N.Y.) 2023; 29:1754-1771. [PMID: 37604684 PMCID: PMC10578481 DOI: 10.1261/rna.079627.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 07/30/2023] [Indexed: 08/23/2023]
Abstract
The s2m, a highly conserved 41-nt hairpin structure in the SARS-CoV-2 genome, serves as an attractive therapeutic target that may have important roles in the virus life cycle or interactions with the host. However, the conserved s2m in Delta SARS-CoV-2, a previously dominant variant characterized by high infectivity and disease severity, has received relatively less attention than that of the original SARS-CoV-2 virus. The focus of this work is to identify and define the s2m changes between Delta and SARS-CoV-2 and the subsequent impact of those changes upon the s2m dimerization and interactions with the host microRNA miR-1307-3p. Bioinformatics analysis of the GISAID database targeting the s2m element reveals a >99% correlation of a single nucleotide mutation at the 15th position (G15U) in Delta SARS-CoV-2. Based on 1H NMR spectroscopy assignments comparing the imino proton resonance region of s2m and the s2m G15U at 19°C, we show that the U15-A29 base pair closes, resulting in a stabilization of the upper stem without overall secondary structure deviation. Increased stability of the upper stem did not affect the chaperone activity of the viral N protein, as it was still able to convert the kissing dimers formed by s2m G15U into a stable duplex conformation, consistent with the s2m reference. However, we show that the s2m G15U mutation drastically impacts the binding of host miR-1307-3p. These findings demonstrate that the observed G15U mutation alters the secondary structure of s2m with subsequent impact on viral binding of host miR-1307-3p, with potential consequences on immune responses.
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Affiliation(s)
- Caylee L Cunningham
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282, USA
| | - Caleb J Frye
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282, USA
| | - Joseph A Makowski
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282, USA
| | - Adam H Kensinger
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282, USA
| | - Morgan Shine
- Department of Biochemistry and Chemistry, Westminster College, New Wilmington, Pennsylvania 16172, USA
| | - Ella J Milback
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282, USA
| | - Patrick E Lackey
- Department of Biochemistry and Chemistry, Westminster College, New Wilmington, Pennsylvania 16172, USA
| | - Jeffrey D Evanseck
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282, USA
| | - Mihaela-Rita Mihailescu
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282, USA
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12
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Estelle AB, Forsythe HM, Yu Z, Hughes K, Lasher B, Allen P, Reardon PN, Hendrix DA, Barbar EJ. RNA structure and multiple weak interactions balance the interplay between RNA binding and phase separation of SARS-CoV-2 nucleocapsid. PNAS NEXUS 2023; 2:pgad333. [PMID: 37901441 PMCID: PMC10605006 DOI: 10.1093/pnasnexus/pgad333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/02/2023] [Accepted: 10/02/2023] [Indexed: 10/31/2023]
Abstract
The nucleocapsid (N) protein of SARS-CoV-2 binds viral RNA, condensing it inside the virion, and phase separating with RNA to form liquid-liquid condensates. There is little consensus on what differentiates sequence-independent N-RNA interactions in the virion or in liquid droplets from those with specific genomic RNA (gRNA) motifs necessary for viral function inside infected cells. To identify the RNA structures and the N domains responsible for specific interactions and phase separation, we use the first 1,000 nt of viral RNA and short RNA segments designed as models for single-stranded and paired RNA. Binding affinities estimated from fluorescence anisotropy of these RNAs to the two-folded domains of N (the NTD and CTD) and comparison to full-length N demonstrate that the NTD binds preferentially to single-stranded RNA, and while it is the primary RNA-binding site, it is not essential to phase separation. Nuclear magnetic resonance spectroscopy identifies two RNA-binding sites on the NTD: a previously characterized site and an additional although weaker RNA-binding face that becomes prominent when binding to the primary site is weak, such as with dsRNA or a binding-impaired mutant. Phase separation assays of nucleocapsid domains with double-stranded and single-stranded RNA structures support a model where multiple weak interactions, such as with the CTD or the NTD's secondary face promote phase separation, while strong, specific interactions do not. These studies indicate that both strong and multivalent weak N-RNA interactions underlie the multifunctional abilities of N.
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Affiliation(s)
- Aidan B Estelle
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331, USA
| | - Heather M Forsythe
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331, USA
| | - Zhen Yu
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331, USA
| | - Kaitlyn Hughes
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331, USA
| | - Brittany Lasher
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331, USA
| | - Patrick Allen
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331, USA
| | - Patrick N Reardon
- Oregon State University NMR Facility, Oregon State University, Corvallis, OR 97331, USA
| | - David A Hendrix
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331, USA
- School of Electrical Engineering and Computer Science, Oregon State University, Corvallis, OR 97331, USA
| | - Elisar J Barbar
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331, USA
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13
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Cunningham CL, Frye CJ, Makowski JA, Kensinger AH, Shine M, Milback EJ, Lackey PE, Evanseck JD, Mihailescu MR. Effect of the SARS-CoV-2 Delta-associated G15U mutation on the s2m element dimerization and its interactions with miR-1307-3p. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.10.528014. [PMID: 36798421 PMCID: PMC9934655 DOI: 10.1101/2023.02.10.528014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
The stem loop 2 motif (s2m), a highly conserved 41-nucleotide hairpin structure in the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genome, serves as an attractive therapeutic target that may have important roles in the virus life cycle or interactions with the host. However, the conserved s2m in Delta SARS-CoV-2, a previously dominant variant characterized by high infectivity and disease severity, has received relatively less attention than that of the original SARS-CoV-2 virus. The focus of this work is to identify and define the s2m changes between Delta and SARS-CoV-2 and subsequent impact of those changes upon the s2m dimerization and interactions with the host microRNA miR-1307-3p. Bioinformatics analysis of the GISAID database targeting the s2m element reveals a greater than 99% correlation of a single nucleotide mutation at the 15 th position (G15U) in Delta SARS-CoV-2. Based on 1 H NMR assignments comparing the imino proton resonance region of s2m and the G15U at 19°C, we find that the U15-A29 base pair closes resulting in a stabilization of the upper stem without overall secondary structure deviation. Increased stability of the upper stem did not affect the chaperone activity of the viral N protein, as it was still able to convert the kissing dimers formed by s2m G15U into a stable duplex conformation, consistent with the s2m reference. However, we find that the s2m G15U mutation drastically reduces the binding affinity of the host miR-1307-3p. These findings demonstrate that the observed G15U mutation alters the secondary structure of s2m with subsequent impact on viral binding of host miR-1307-3p, with potential consequences on the immune response.
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