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Walia K, Sharma A, Paul S, Chouhan P, Kumar G, Ringe R, Sharma M, Tuli A. SARS-CoV-2 virulence factor ORF3a blocks lysosome function by modulating TBC1D5-dependent Rab7 GTPase cycle. Nat Commun 2024; 15:2053. [PMID: 38448435 PMCID: PMC10918171 DOI: 10.1038/s41467-024-46417-2] [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: 06/12/2023] [Accepted: 02/26/2024] [Indexed: 03/08/2024] Open
Abstract
SARS-CoV-2, the causative agent of COVID-19, uses the host endolysosomal system for entry, replication, and egress. Previous studies have shown that the SARS-CoV-2 virulence factor ORF3a interacts with the lysosomal tethering factor HOPS complex and blocks HOPS-mediated late endosome and autophagosome fusion with lysosomes. Here, we report that SARS-CoV-2 infection leads to hyperactivation of the late endosomal and lysosomal small GTP-binding protein Rab7, which is dependent on ORF3a expression. We also observed Rab7 hyperactivation in naturally occurring ORF3a variants encoded by distinct SARS-CoV-2 variants. We found that ORF3a, in complex with Vps39, sequesters the Rab7 GAP TBC1D5 and displaces Rab7 from this complex. Thus, ORF3a disrupts the GTP hydrolysis cycle of Rab7, which is beneficial for viral production, whereas the Rab7 GDP-locked mutant strongly reduces viral replication. Hyperactivation of Rab7 in ORF3a-expressing cells impaired CI-M6PR retrieval from late endosomes to the trans-Golgi network, disrupting the biosynthetic transport of newly synthesized hydrolases to lysosomes. Furthermore, the tethering of the Rab7- and Arl8b-positive compartments was strikingly reduced upon ORF3a expression. As SARS-CoV-2 egress requires Arl8b, these findings suggest that ORF3a-mediated hyperactivation of Rab7 serves a multitude of functions, including blocking endolysosome formation, interrupting the transport of lysosomal hydrolases, and promoting viral egress.
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Affiliation(s)
- Kshitiz Walia
- Division of Cell Biology and Immunology, CSIR-Institute of Microbial Technology (IMTECH), Chandigarh, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, Uttar Pradesh, India
| | - Abhishek Sharma
- Division of Cell Biology and Immunology, CSIR-Institute of Microbial Technology (IMTECH), Chandigarh, India
| | - Sankalita Paul
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Mohali, Punjab, India
| | - Priya Chouhan
- Division of Cell Biology and Immunology, CSIR-Institute of Microbial Technology (IMTECH), Chandigarh, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, Uttar Pradesh, India
| | - Gaurav Kumar
- Division of Cell Biology and Immunology, CSIR-Institute of Microbial Technology (IMTECH), Chandigarh, India
| | - Rajesh Ringe
- Division of Cell Biology and Immunology, CSIR-Institute of Microbial Technology (IMTECH), Chandigarh, India
| | - Mahak Sharma
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Mohali, Punjab, India
| | - Amit Tuli
- Division of Cell Biology and Immunology, CSIR-Institute of Microbial Technology (IMTECH), Chandigarh, India.
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, Uttar Pradesh, India.
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2
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Chatterjee S, Zaia J. Proteomics-based mass spectrometry profiling of SARS-CoV-2 infection from human nasopharyngeal samples. MASS SPECTROMETRY REVIEWS 2024; 43:193-229. [PMID: 36177493 PMCID: PMC9538640 DOI: 10.1002/mas.21813] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 09/07/2022] [Accepted: 09/09/2022] [Indexed: 05/12/2023]
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the cause of the on-going global pandemic of coronavirus disease 2019 (COVID-19) that continues to pose a significant threat to public health worldwide. SARS-CoV-2 encodes four structural proteins namely membrane, nucleocapsid, spike, and envelope proteins that play essential roles in viral entry, fusion, and attachment to the host cell. Extensively glycosylated spike protein efficiently binds to the host angiotensin-converting enzyme 2 initiating viral entry and pathogenesis. Reverse transcriptase polymerase chain reaction on nasopharyngeal swab is the preferred method of sample collection and viral detection because it is a rapid, specific, and high-throughput technique. Alternate strategies such as proteomics and glycoproteomics-based mass spectrometry enable a more detailed and holistic view of the viral proteins and host-pathogen interactions and help in detection of potential disease markers. In this review, we highlight the use of mass spectrometry methods to profile the SARS-CoV-2 proteome from clinical nasopharyngeal swab samples. We also highlight the necessity for a comprehensive glycoproteomics mapping of SARS-CoV-2 from biological complex matrices to identify potential COVID-19 markers.
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Affiliation(s)
- Sayantani Chatterjee
- Department of Biochemistry, Center for Biomedical Mass SpectrometryBoston University School of MedicineBostonMassachusettsUSA
| | - Joseph Zaia
- Department of Biochemistry, Center for Biomedical Mass SpectrometryBoston University School of MedicineBostonMassachusettsUSA
- Bioinformatics ProgramBoston University School of MedicineBostonMassachusettsUSA
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3
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Rout M, Mishra S, Panda S, Dehury B, Pati S. Lipid and cholesterols modulate the dynamics of SARS-CoV-2 viral ion channel ORF3a and its pathogenic variants. Int J Biol Macromol 2024; 254:127986. [PMID: 37944718 DOI: 10.1016/j.ijbiomac.2023.127986] [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: 08/24/2023] [Revised: 11/06/2023] [Accepted: 11/07/2023] [Indexed: 11/12/2023]
Abstract
SARS-CoV-2 accessory protein, ORF3a is a putative ion channel which immensely contributes to viral pathogenicity by modulating host immune responses and virus-host interactions. Relatively high expression of ORF3a in diseased individuals and implication with inflammasome activation, apoptosis and autophagy inhibition, ratifies as an effective target for developing vaccines and therapeutics. Herein, we present the elusive dynamics of ORF3a-dimeric state using all-atoms molecular dynamics (MD) simulations at μ-seconds scale in a heterogeneous lipid-mimetic system in multiple replicates. Additionally, we also explore the effect of non-synonymous pathogenic mutations on ORF3a ion channel activity and viral pathogenicity in different SARS-CoV-2 variants using various structure-based protein stability (ΔΔG) tools and computational saturation mutagenesis. Our study ascertains the role of phosphatidylcholines and cholesterol in modulating the structure of ORF3a, which perturbs the size and flexibility of the polar cavity that allows permeation of large cations. Discrete trend in ion channel pore radius and area per lipid arises the premise that presence of lipids might also affect the overall conformation of ORF3a. MD structural-ensembles, in some replicates rationalize the crucial role of TM2 in maintaining the native structure of ORF3a. We also infer that loss of structural stability primarily grounds for pathogenicity in more than half of the pathogenic variants of ORF3a. Overall, the effect of mutation on alteration of ion permeability of ORF3a, proposed in this study brings mechanistic insights into variant consequences on viral membrane proteins of SARS-CoV-2, which can be utilized for the development of novel therapeutics to treat COVID-19 and other coronavirus diseases.
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Affiliation(s)
- Madhusmita Rout
- Bioinformatics Division, ICMR-Regional Medical Research Centre, Chandrasekharpur, Bhubaneswar 751023, Odisha, India
| | - Sarbani Mishra
- Bioinformatics Division, ICMR-Regional Medical Research Centre, Chandrasekharpur, Bhubaneswar 751023, Odisha, India
| | - Sunita Panda
- Mycology Division, ICMR-Regional Medical Research Centre, Chandrasekharpur, Bhubaneswar 751023, Odisha, India
| | - Budheswar Dehury
- Bioinformatics Division, ICMR-Regional Medical Research Centre, Chandrasekharpur, Bhubaneswar 751023, Odisha, India.
| | - Sanghamitra Pati
- Bioinformatics Division, ICMR-Regional Medical Research Centre, Chandrasekharpur, Bhubaneswar 751023, Odisha, India.
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4
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Cheng J, Zeng H, Chen H, Fan L, Xu C, Huang H, Tang T, Li M. Current knowledge of thrombocytopenia in sepsis and COVID-19. Front Immunol 2023; 14:1213510. [PMID: 37841241 PMCID: PMC10568455 DOI: 10.3389/fimmu.2023.1213510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 09/12/2023] [Indexed: 10/17/2023] Open
Abstract
Thrombocytopenia, characterized by a decrease in platelet count, is commonly observed in sepsis and COVID-19. In sepsis, thrombocytopenia can result from various mechanisms, including impaired platelet production in the bone marrow, accelerated platelet destruction due to increased inflammation, sequestration of platelets in the spleen, immune-mediated platelet destruction, or dysregulated host responses. Similarly, thrombocytopenia has been reported in COVID-19 patients, but the immune-related mechanisms underlying this association remain unclear. Notably, interventions targeting thrombocytopenia have shown potential for improving outcomes in both sepsis and COVID-19 patients. Understanding these mechanisms is crucial for developing effective treatments.
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Affiliation(s)
- Junjie Cheng
- Intensive Care Unit, The Fourth Affiliated Hospital, School of Medicine, Zhejiang University, Yiwu, China
| | - Hanhai Zeng
- Department of Neurosurgery, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Huaijun Chen
- Department of Neurosurgery, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Linfeng Fan
- Department of Neurosurgery, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Chaoran Xu
- Department of Neurosurgery, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Huaping Huang
- Department of Neurosurgery, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Tianchi Tang
- Department of Neurosurgery, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Min Li
- Intensive Care Unit, The Fourth Affiliated Hospital, School of Medicine, Zhejiang University, Yiwu, China
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5
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Miller AN, Houlihan PR, Matamala E, Cabezas-Bratesco D, Lee GY, Cristofori-Armstrong B, Dilan TL, Sanchez-Martinez S, Matthies D, Yan R, Yu Z, Ren D, Brauchi SE, Clapham DE. The SARS-CoV-2 accessory protein Orf3a is not an ion channel, but does interact with trafficking proteins. eLife 2023; 12:e84477. [PMID: 36695574 PMCID: PMC9910834 DOI: 10.7554/elife.84477] [Citation(s) in RCA: 19] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 01/25/2023] [Indexed: 01/26/2023] Open
Abstract
The severe acute respiratory syndrome associated coronavirus 2 (SARS-CoV-2) and SARS-CoV-1 accessory protein Orf3a colocalizes with markers of the plasma membrane, endocytic pathway, and Golgi apparatus. Some reports have led to annotation of both Orf3a proteins as viroporins. Here, we show that neither SARS-CoV-2 nor SARS-CoV-1 Orf3a form functional ion conducting pores and that the conductances measured are common contaminants in overexpression and with high levels of protein in reconstitution studies. Cryo-EM structures of both SARS-CoV-2 and SARS-CoV-1 Orf3a display a narrow constriction and the presence of a positively charged aqueous vestibule, which would not favor cation permeation. We observe enrichment of the late endosomal marker Rab7 upon SARS-CoV-2 Orf3a overexpression, and co-immunoprecipitation with VPS39. Interestingly, SARS-CoV-1 Orf3a does not cause the same cellular phenotype as SARS-CoV-2 Orf3a and does not interact with VPS39. To explain this difference, we find that a divergent, unstructured loop of SARS-CoV-2 Orf3a facilitates its binding with VPS39, a HOPS complex tethering protein involved in late endosome and autophagosome fusion with lysosomes. We suggest that the added loop enhances SARS-CoV-2 Orf3a's ability to co-opt host cellular trafficking mechanisms for viral exit or host immune evasion.
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Affiliation(s)
| | | | - Ella Matamala
- Physiology Institute and Millennium Nucleus of Ion Channel-Associated Diseases, Universidad Austral de ChileValdiviaChile
| | - Deny Cabezas-Bratesco
- Physiology Institute and Millennium Nucleus of Ion Channel-Associated Diseases, Universidad Austral de ChileValdiviaChile
| | - Gi Young Lee
- Department of Biology, University of PennsylvaniaPhiladelphiaUnited States
| | | | | | | | | | - Rui Yan
- Janelia Research CampusAshburnUnited States
| | - Zhiheng Yu
- Janelia Research CampusAshburnUnited States
| | - Dejian Ren
- Department of Biology, University of PennsylvaniaPhiladelphiaUnited States
| | - Sebastian E Brauchi
- Janelia Research CampusAshburnUnited States
- Physiology Institute and Millennium Nucleus of Ion Channel-Associated Diseases, Universidad Austral de ChileValdiviaChile
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6
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Jahirul Islam M, Nawal Islam N, Siddik Alom M, Kabir M, Halim MA. A review on structural, non-structural, and accessory proteins of SARS-CoV-2: Highlighting drug target sites. Immunobiology 2023; 228:152302. [PMID: 36434912 PMCID: PMC9663145 DOI: 10.1016/j.imbio.2022.152302] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Revised: 10/30/2022] [Accepted: 11/10/2022] [Indexed: 11/16/2022]
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of COVID-19, is a highly transmittable and pathogenic human coronavirus that first emerged in China in December 2019. The unprecedented outbreak of SARS-CoV-2 devastated human health within a short time leading to a global public health emergency. A detailed understanding of the viral proteins including their structural characteristics and virulence mechanism on human health is very crucial for developing vaccines and therapeutics. To date, over 1800 structures of non-structural, structural, and accessory proteins of SARS-CoV-2 are determined by cryo-electron microscopy, X-ray crystallography, and NMR spectroscopy. Designing therapeutics to target the viral proteins has several benefits since they could be highly specific against the virus while maintaining minimal detrimental effects on humans. However, for ongoing and future research on SARS-CoV-2, summarizing all the viral proteins and their detailed structural information is crucial. In this review, we compile comprehensive information on viral structural, non-structural, and accessory proteins structures with their binding and catalytic sites, different domain and motifs, and potential drug target sites to assist chemists, biologists, and clinicians finding necessary details for fundamental and therapeutic research.
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Affiliation(s)
- Md. Jahirul Islam
- Division of Infectious Diseases and Division of Computer Aided Drug Design, The Red-Green Research Centre, BICCB, 16 Tejkunipara, Tejgaon, Dhaka 1215, Bangladesh
| | - Nafisa Nawal Islam
- Department of Biotechnology and Genetic Engineering, Jahangirnagar University, Savar, Dhaka 1342, Bangladesh
| | - Md. Siddik Alom
- Ohio State Biochemistry Program, The Ohio State University, Columbus, OH 43210, USA
| | - Mahmuda Kabir
- Department of Genetic Engineering and Biotechnology, University of Dhaka, Dhaka 1000, Bangladesh
| | - Mohammad A. Halim
- Department of Chemistry and Biochemistry, Kennesaw State University, 370 Paulding Avenue NW, Kennesaw, GA 30144, USA,Corresponding author
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7
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Miller AN, Houlihan PR, Matamala E, Cabezas-Bratesco D, Lee GY, Cristofori-Armstrong B, Dilan TL, Sanchez-Martinez S, Matthies D, Yan R, Yu Z, Ren D, Brauchi SE, Clapham DE. The SARS-CoV-2 accessory protein Orf3a is not an ion channel, but does interact with trafficking proteins. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2022:2022.09.02.506428. [PMID: 36263072 PMCID: PMC9580380 DOI: 10.1101/2022.09.02.506428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The severe acute respiratory syndrome associated coronavirus 2 (SARS-CoV-2) and SARS-CoV-1 accessory protein Orf3a colocalizes with markers of the plasma membrane, endocytic pathway, and Golgi apparatus. Some reports have led to annotation of both Orf3a proteins as a viroporin. Here we show that neither SARS-CoV-2 nor SARS-CoV-1 form functional ion conducting pores and that the conductances measured are common contaminants in overexpression and with high levels of protein in reconstitution studies. Cryo-EM structures of both SARS-CoV-2 and SARS-CoV-1 Orf3a display a narrow constriction and the presence of a basic aqueous vestibule, which would not favor cation permeation. We observe enrichment of the late endosomal marker Rab7 upon SARS-CoV-2 Orf3a overexpression, and co-immunoprecipitation with VPS39. Interestingly, SARS-CoV-1 Orf3a does not cause the same cellular phenotype as SARS-CoV-2 Orf3a and does not interact with VPS39. To explain this difference, we find that a divergent, unstructured loop of SARS-CoV-2 Orf3a facilitates its binding with VPS39, a HOPS complex tethering protein involved in late endosome and autophagosome fusion with lysosomes. We suggest that the added loop enhances SARS-CoV-2 Orf3a ability to co-opt host cellular trafficking mechanisms for viral exit or host immune evasion.
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8
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Zhang J, Ejikemeuwa A, Gerzanich V, Nasr M, Tang Q, Simard JM, Zhao RY. Understanding the Role of SARS-CoV-2 ORF3a in Viral Pathogenesis and COVID-19. Front Microbiol 2022; 13:854567. [PMID: 35356515 PMCID: PMC8959714 DOI: 10.3389/fmicb.2022.854567] [Citation(s) in RCA: 43] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 02/09/2022] [Indexed: 12/11/2022] Open
Abstract
The ongoing SARS-CoV-2 pandemic has shocked the world due to its persistence, COVID-19-related morbidity and mortality, and the high mutability of the virus. One of the major concerns is the emergence of new viral variants that may increase viral transmission and disease severity. In addition to mutations of spike protein, mutations of viral proteins that affect virulence, such as ORF3a, also must be considered. The purpose of this article is to review the current literature on ORF3a, to summarize the molecular actions of SARS-CoV-2 ORF3a, and its role in viral pathogenesis and COVID-19. ORF3a is a polymorphic, multifunctional viral protein that is specific to SARS-CoV/SARS-CoV-2. It was acquired from β-CoV lineage and likely originated from bats through viral evolution. SARS-CoV-2 ORF3a is a viroporin that interferes with ion channel activities in host plasma and endomembranes. It is likely a virion-associated protein that exerts its effect on the viral life cycle during viral entry through endocytosis, endomembrane-associated viral transcription and replication, and viral release through exocytosis. ORF3a induces cellular innate and pro-inflammatory immune responses that can trigger a cytokine storm, especially under hypoxic conditions, by activating NLRP3 inflammasomes, HMGB1, and HIF-1α to promote the production of pro-inflammatory cytokines and chemokines. ORF3a induces cell death through apoptosis, necrosis, and pyroptosis, which leads to tissue damage that affects the severity of COVID-19. ORF3a continues to evolve along with spike and other viral proteins to adapt in the human cellular environment. How the emerging ORF3a mutations alter the function of SARS-CoV-2 ORF3a and its role in viral pathogenesis and COVID-19 is largely unknown. This review provides an in-depth analysis of ORF3a protein's structure, origin, evolution, and mutant variants, and how these characteristics affect its functional role in viral pathogenesis and COVID-19.
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Affiliation(s)
- Jiantao Zhang
- Department of Pathology, University of Maryland School of Medicine, Baltimore, MD, United States
- Research and Development Service, VA Maryland Health Care System, Baltimore, MD, United States
| | - Amara Ejikemeuwa
- Department of Pathology, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Volodymyr Gerzanich
- Research and Development Service, VA Maryland Health Care System, Baltimore, MD, United States
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Mohamed Nasr
- Drug Development and Clinical Sciences Branch, Division of AIDS, NIAID, NIH, Bethesda, MD, United States
| | - Qiyi Tang
- Department of Microbiology, Howard University College of Medicine, Washington, DC, United States
| | - J. Marc Simard
- Department of Pathology, University of Maryland School of Medicine, Baltimore, MD, United States
- Research and Development Service, VA Maryland Health Care System, Baltimore, MD, United States
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Richard Y. Zhao
- Department of Pathology, University of Maryland School of Medicine, Baltimore, MD, United States
- Research and Development Service, VA Maryland Health Care System, Baltimore, MD, United States
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, United States
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, MD, United States
- Institute of Global Health, University of Maryland School of Medicine, Baltimore, MD, United States
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9
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Wade H, Duan Q, Su Q. Interaction between Sars-CoV-2 structural proteins and host cellular receptors: From basic mechanisms to clinical perspectives. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2022; 132:243-277. [PMID: 36088078 PMCID: PMC9182089 DOI: 10.1016/bs.apcsb.2022.05.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Severe acute respiratory syndrome coronavirus 2 (Sars-CoV-2) has caused a global pandemic that has affected the lives of billions of individuals. Sars-CoV-2 primarily infects human cells by binding of the viral spike protein to angiotensin-converting enzyme 2 (ACE2). In addition, novel means of viral entry are currently being investigated, including Neuropillin 1, toll-like receptors (TLRs), cluster of differentiation 147 (CD147), and integrin α5β1. Enriched expression of these proteins across metabolic regulatory organs/tissues, including the circulatory system, liver, pancreas, and intestine contributes to major clinical complications among COVID-19 patients, particularly the development of hypertension, myocardial injury, arrhythmia, acute coronary syndrome and increased coagulation in the circulatory system during and post-infection. Pre-existing metabolic disease, such as cardiovascular disease, obesity, diabetes, and non-alcoholic fatty liver disease, is associated with increased risk of hospitalization, persistent post-infection complications and worse outcomes in patients with COVID-19. This review overviews the biological features of Sars-CoV-2, highlights recent findings that delineate the pathological mechanisms of COVID-19 and the consequent clinical diseases.
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Tan TH, Patton E, Munro CA, Corzo-Leon DE, Porter AJ, Palliyil S. Monoclonal Human Antibodies That Recognise the Exposed N and C Terminal Regions of the Often-Overlooked SARS-CoV-2 ORF3a Transmembrane Protein. Viruses 2021; 13:2201. [PMID: 34835009 PMCID: PMC8624585 DOI: 10.3390/v13112201] [Citation(s) in RCA: 3] [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: 09/24/2021] [Revised: 10/15/2021] [Accepted: 10/29/2021] [Indexed: 11/23/2022] Open
Abstract
ORF3a has been identified as a viroporin of SARS-CoV-2 and is known to be involved in various pathophysiological activities including disturbance of cellular calcium homeostasis, inflammasome activation, apoptosis induction and disruption of autophagy. ORF3a-targeting antibodies may specifically and favorably modulate these viroporin-dependent pathological activities. However, suitable viroporin-targeting antibodies are difficult to generate because of the well-recognized technical challenge associated with isolating antibodies to complex transmembrane proteins. Here we exploited a naïve human single chain antibody phage display library, to isolate binders against carefully chosen ORF3a recombinant epitopes located towards the extracellular N terminal and cytosolic C terminal domains of the protein using peptide antigens. These binders were subjected to further characterization using enzyme-linked immunosorbent assays and surface plasmon resonance analysis to assess their binding affinities to the target epitopes. Binding to full-length ORF3a protein was evaluated by western blot and fluorescent microscopy using ORF3a transfected cells and SARS-CoV-2 infected cells. Co-localization analysis was also performed to evaluate the "pairing potential" of the selected binders as possible alternative diagnostic or prognostic biomarkers for COVID-19 infections. Both ORF3a N and C termini, epitope-specific monoclonal antibodies were identified in our study. Whilst the linear nature of peptides might not always represent their native conformations in the context of full protein, with carefully designed selection protocols, we have been successful in isolating anti-ORF3a binders capable of recognising regions of the transmembrane protein that are exposed either on the "inside" or "outside" of the infected cell. Their therapeutic potential will be discussed.
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Affiliation(s)
- Tyng Hwey Tan
- Scottish Biologics Facility, Institute of Medical Sciences, School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZP, UK; (T.H.T.); (E.P.)
- Aberdeen Fungal Group, Institute of Medical Sciences, School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK; (C.A.M.); (D.E.C.-L.)
| | - Elizabeth Patton
- Scottish Biologics Facility, Institute of Medical Sciences, School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZP, UK; (T.H.T.); (E.P.)
| | - Carol A. Munro
- Aberdeen Fungal Group, Institute of Medical Sciences, School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK; (C.A.M.); (D.E.C.-L.)
| | - Dora E. Corzo-Leon
- Aberdeen Fungal Group, Institute of Medical Sciences, School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK; (C.A.M.); (D.E.C.-L.)
| | - Andrew J. Porter
- Scottish Biologics Facility, Institute of Medical Sciences, School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZP, UK; (T.H.T.); (E.P.)
| | - Soumya Palliyil
- Scottish Biologics Facility, Institute of Medical Sciences, School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZP, UK; (T.H.T.); (E.P.)
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11
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Gargan S, Stevenson NJ. Unravelling the Immunomodulatory Effects of Viral Ion Channels, towards the Treatment of Disease. Viruses 2021; 13:2165. [PMID: 34834972 PMCID: PMC8618147 DOI: 10.3390/v13112165] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 09/07/2021] [Accepted: 10/10/2021] [Indexed: 02/07/2023] Open
Abstract
The current COVID-19 pandemic has highlighted the need for the research community to develop a better understanding of viruses, in particular their modes of infection and replicative lifecycles, to aid in the development of novel vaccines and much needed anti-viral therapeutics. Several viruses express proteins capable of forming pores in host cellular membranes, termed "Viroporins". They are a family of small hydrophobic proteins, with at least one amphipathic domain, which characteristically form oligomeric structures with central hydrophilic domains. Consequently, they can facilitate the transport of ions through the hydrophilic core. Viroporins localise to host membranes such as the endoplasmic reticulum and regulate ion homeostasis creating a favourable environment for viral infection. Viroporins also contribute to viral immune evasion via several mechanisms. Given that viroporins are often essential for virion assembly and egress, and as their structural features tend to be evolutionarily conserved, they are attractive targets for anti-viral therapeutics. This review discusses the current knowledge of several viroporins, namely Influenza A virus (IAV) M2, Human Immunodeficiency Virus (HIV)-1 Viral protein U (Vpu), Hepatitis C Virus (HCV) p7, Human Papillomavirus (HPV)-16 E5, Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) Open Reading Frame (ORF)3a and Polyomavirus agnoprotein. We highlight the intricate but broad immunomodulatory effects of these viroporins and discuss the current antiviral therapies that target them; continually highlighting the need for future investigations to focus on novel therapeutics in the treatment of existing and future emergent viruses.
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Affiliation(s)
- Siobhan Gargan
- Viral Immunology Group, School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, D02 R590 Dublin, Ireland;
| | - Nigel J. Stevenson
- Viral Immunology Group, School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, D02 R590 Dublin, Ireland;
- Viral Immunology Group, Royal College of Surgeons in Ireland-Medical University of Bahrain, Manama 15503, Bahrain
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12
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Chakraborty S, Mallajosyula V, Tato CM, Tan GS, Wang TT. SARS-CoV-2 vaccines in advanced clinical trials: Where do we stand? Adv Drug Deliv Rev 2021; 172:314-338. [PMID: 33482248 PMCID: PMC7816567 DOI: 10.1016/j.addr.2021.01.014] [Citation(s) in RCA: 58] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 01/11/2021] [Accepted: 01/14/2021] [Indexed: 02/07/2023]
Abstract
The ongoing SARS-CoV-2 pandemic has led to the focused application of resources and scientific expertise toward the goal of developing investigational vaccines to prevent COVID-19. The highly collaborative global efforts by private industry, governments and non-governmental organizations have resulted in a number of SARS-CoV-2 vaccine candidates moving to Phase III trials in a period of only months since the start of the pandemic. In this review, we provide an overview of the preclinical and clinical data on SARS-CoV-2 vaccines that are currently in Phase III clinical trials and in few cases authorized for emergency use. We further discuss relevant vaccine platforms and provide a discussion of SARS-CoV-2 antigens that may be targeted to increase the breadth and durability of vaccine responses.
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Affiliation(s)
- Saborni Chakraborty
- Department of Medicine, Division of Infectious Diseases, Stanford University, Stanford, CA, USA
| | - Vamsee Mallajosyula
- Institute for Immunity, Transplantation, and Infection, Stanford University, Stanford, CA, USA
| | - Cristina M Tato
- Infectious Disease Initiative, Chan Zuckerberg Biohub, San Francisco, CA, USA
| | - Gene S Tan
- J. Craig Venter Institute, 4120 Capricorn Lane, La Jolla, CA 92037, USA; Department of Infectious Diseases, University of California San Diego, La Jolla, CA 92037, USA
| | - Taia T Wang
- Department of Medicine, Division of Infectious Diseases, Stanford University, Stanford, CA, USA; Department of Microbiology and Immunology, Stanford University, Stanford, CA, USA; Chan Zuckerberg Biohub, San Francisco, CA, USA.
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13
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Harnish JM, Link N, Yamamoto S. Drosophila as a Model for Infectious Diseases. Int J Mol Sci 2021; 22:2724. [PMID: 33800390 PMCID: PMC7962867 DOI: 10.3390/ijms22052724] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 02/11/2021] [Accepted: 02/14/2021] [Indexed: 12/19/2022] Open
Abstract
The fruit fly, Drosophila melanogaster, has been used to understand fundamental principles of genetics and biology for over a century. Drosophila is now also considered an essential tool to study mechanisms underlying numerous human genetic diseases. In this review, we will discuss how flies can be used to deepen our knowledge of infectious disease mechanisms in vivo. Flies make effective and applicable models for studying host-pathogen interactions thanks to their highly conserved innate immune systems and cellular processes commonly hijacked by pathogens. Drosophila researchers also possess the most powerful, rapid, and versatile tools for genetic manipulation in multicellular organisms. This allows for robust experiments in which specific pathogenic proteins can be expressed either one at a time or in conjunction with each other to dissect the molecular functions of each virulent factor in a cell-type-specific manner. Well documented phenotypes allow large genetic and pharmacological screens to be performed with relative ease using huge collections of mutant and transgenic strains that are publicly available. These factors combine to make Drosophila a powerful tool for dissecting out host-pathogen interactions as well as a tool to better understand how we can treat infectious diseases that pose risks to public health, including COVID-19, caused by SARS-CoV-2.
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Affiliation(s)
- J. Michael Harnish
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; (J.M.H.); (N.L.)
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, TX 77030, USA
| | - Nichole Link
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; (J.M.H.); (N.L.)
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, TX 77030, USA
- Howard Hughes Medical Institute, Houston, TX 77030, USA
| | - Shinya Yamamoto
- Department of Molecular and Human Genetics, Baylor College of Medicine (BCM), Houston, TX 77030, USA; (J.M.H.); (N.L.)
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, TX 77030, USA
- Department of Neuroscience, BCM, Houston, TX 77030, USA
- Development, Disease Models and Therapeutics Graduate Program, BCM, Houston, TX 77030, USA
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14
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Mohammed MEA. SARS-CoV-2 proteins: Are they useful as targets for COVID-19 drugs and vaccines? Curr Mol Med 2021; 22:50-66. [PMID: 33622224 DOI: 10.2174/1566524021666210223143243] [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: 10/01/2020] [Revised: 01/28/2021] [Accepted: 02/02/2021] [Indexed: 11/22/2022]
Abstract
The proteins of coronavirus are classified to nonstructural, structural, and accessory. There are 16 nonstructural viral proteins beside their precursors (1a and 1ab polyproteins). The nonstructural proteins are named as nsp1 to nsp16 and they act as enzymes, coenzymes, and binding proteins to facilitate the replication, transcription, and translation of the virus. The structural proteins are bound to the RNA in the nucleocapsid (N- protein) or to the lipid bilayer membrane of the viral envelope. The lipid bilayer proteins include the membrane protein (M), envelope protein (E), and spike protein (S). Beside their role as structural proteins, they are essential for the host cells binding and invasion. The SARS-CoV-2 contains six accessory proteins which participates in the viral replication, assembly and virus- host interactions. The SARS-CoV-2 accessory proteins are orf3a, orf6, orf7a, orf7b, orf8, and orf10. The functions of the SARS-CoV-2 are not well known, while the functions of their corresponding proteins in SARS-CoV are either well known or poorly studied. Recently, the Oxford University and Pfizer and BioNTech made SARS-CoV-2 vaccines through targeting the spike protein gene. The US Food and Drug Administration (FDA) and the health authorities of the United Kingdom approved and started vaccination using the Pfizer and BioNTech mRNA vaccine. Also, The FDA of USA approved the treatment of COVID-19 using two monoclonal antibodies produced by Regeneron pharmaceuticals to target the spike protein. The SARS-CoV-2 proteins can be used for the diagnosis, as drug targets and in vaccination trials for COVID-19. For future COVID-19 research, more efforts should be done to elaborate the functions and structure of the SARS-CoV-2 proteins so as to use them as targets for COVID-19 drug and vaccines. Special attention should be drawn to extensive research on the SARS-CoV-2 nsp3, orf8, and orf10.
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15
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Giri R, Bhardwaj T, Shegane M, Gehi BR, Kumar P, Gadhave K, Oldfield CJ, Uversky VN. Understanding COVID-19 via comparative analysis of dark proteomes of SARS-CoV-2, human SARS and bat SARS-like coronaviruses. Cell Mol Life Sci 2021; 78:1655-1688. [PMID: 32712910 DOI: 10.1101/2020.03.13.990598] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 07/03/2020] [Accepted: 07/17/2020] [Indexed: 05/18/2023]
Abstract
The recently emerged coronavirus designated as SARS-CoV-2 (also known as 2019 novel coronavirus (2019-nCoV) or Wuhan coronavirus) is a causative agent of coronavirus disease 2019 (COVID-19), which is rapidly spreading throughout the world now. More than 1.21 million cases of SARS-CoV-2 infection and more than 67,000 COVID-19-associated mortalities have been reported worldwide till the writing of this article, and these numbers are increasing every passing hour. The World Health Organization (WHO) has declared the SARS-CoV-2 spread as a global public health emergency and admitted COVID-19 as a pandemic now. Multiple sequence alignment data correlated with the already published reports on SARS-CoV-2 evolution indicated that this virus is closely related to the bat severe acute respiratory syndrome-like coronavirus (bat SARS-like CoV) and the well-studied human SARS coronavirus (SARS-CoV). The disordered regions in viral proteins are associated with the viral infectivity and pathogenicity. Therefore, in this study, we have exploited a set of complementary computational approaches to examine the dark proteomes of SARS-CoV-2, bat SARS-like, and human SARS CoVs by analysing the prevalence of intrinsic disorder in their proteins. According to our findings, SARS-CoV-2 proteome contains very significant levels of structural order. In fact, except for nucleocapsid, Nsp8, and ORF6, the vast majority of SARS-CoV-2 proteins are mostly ordered proteins containing less intrinsically disordered protein regions (IDPRs). However, IDPRs found in SARS-CoV-2 proteins are functionally important. For example, cleavage sites in its replicase 1ab polyprotein are found to be highly disordered, and almost all SARS-CoV-2 proteins contains molecular recognition features (MoRFs), which are intrinsic disorder-based protein-protein interaction sites that are commonly utilized by proteins for interaction with specific partners. The results of our extensive investigation of the dark side of SARS-CoV-2 proteome will have important implications in understanding the structural and non-structural biology of SARS or SARS-like coronaviruses.
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Affiliation(s)
- Rajanish Giri
- School of Basic Sciences, Indian Institute of Technology Mandi, VPO Kamand, Mandi, Himachal Pradesh, 175005, India.
| | - Taniya Bhardwaj
- School of Basic Sciences, Indian Institute of Technology Mandi, VPO Kamand, Mandi, Himachal Pradesh, 175005, India
| | - Meenakshi Shegane
- School of Basic Sciences, Indian Institute of Technology Mandi, VPO Kamand, Mandi, Himachal Pradesh, 175005, India
| | - Bhuvaneshwari R Gehi
- School of Basic Sciences, Indian Institute of Technology Mandi, VPO Kamand, Mandi, Himachal Pradesh, 175005, India
| | - Prateek Kumar
- School of Basic Sciences, Indian Institute of Technology Mandi, VPO Kamand, Mandi, Himachal Pradesh, 175005, India
| | - Kundlik Gadhave
- School of Basic Sciences, Indian Institute of Technology Mandi, VPO Kamand, Mandi, Himachal Pradesh, 175005, India
| | | | - Vladimir N Uversky
- Department of Molecular Medicine, Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL, USA
- Laboratory of New Methods in Biology, Institute for Biological Instrumentation of the Russian Academy of Sciences, Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", Moscow region, Pushchino, 142290, Russia
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16
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Prasansuklab A, Theerasri A, Rangsinth P, Sillapachaiyaporn C, Chuchawankul S, Tencomnao T. Anti-COVID-19 drug candidates: A review on potential biological activities of natural products in the management of new coronavirus infection. J Tradit Complement Med 2020; 11:144-157. [PMID: 33520683 PMCID: PMC7833040 DOI: 10.1016/j.jtcme.2020.12.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 12/24/2020] [Accepted: 12/25/2020] [Indexed: 12/15/2022] Open
Abstract
Background and aim The novel coronavirus disease (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is now become a worldwide pandemic bringing over 71 million confirmed cases, while the specific drugs and vaccines approved for this disease are still limited regarding their effectiveness and adverse events. Since virus incidences are still on rise, infectivity and mortality may also rise in the near future, natural products are highly considered to be valuable sources for the discovery of new antiviral drugs against SARS-CoV-2. This present review aims to comprehensively summarize the up-to-date scientific literatures on biological activities of plant- and mushroom-derived compounds relevant to mechanistic targets involved in SARS-CoV-2 infection and inflammatory-associated pathogenesis, including viral entry, replication and release, and the renin-angiotensin-aldosterone system (RAAS). Experimental procedure Data were retrieved from a literature search available on PubMed, Scopus and Google Scholar databases and collected until the end of May 2020. The findings from in vitro cell and non-cell based studies were considered, while the results of in silico studies were excluded. Results and conclusion Based on the previous findings in SARS-CoV studies, except in silico molecular docking analysis, herein, we provide a total of 150 natural compounds as potential candidates for development of new anti-COVID-19 drugs with higher efficacy and lower toxicity than the existing therapeutic agents. Several natural compounds have showed their promising actions on multiple therapeutic targets, which should be further explored. Among them, quercetin, one of the most abundant of plant flavonoids, is proposed as a lead candidate with its ability on the virus side to inhibit SARS-CoV spike protein-angiotensin-converting enzyme 2 (ACE2) interaction, viral protease and helicase activities, as well as on the host cell side to inhibit ACE activity and increase intracellular zinc level. Relevant and up-to-date publications in natural products with anti-COVID-19 potential. Emphasis on the potential of anti-COVID-19 plant/mushroom-based medicine. Twenty four proposed natural compounds for the anti-COVID-19 drug candidates. Quercetin emerged as the most promising compound acting on multiple therapeutic targets.
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Affiliation(s)
- Anchalee Prasansuklab
- College of Public Health Sciences, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Atsadang Theerasri
- Graduate Program in Clinical Biochemistry and Molecular Medicine, Department of Clinical Chemistry, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Panthakarn Rangsinth
- Immunomodulation of Natural Products Research Group, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Chanin Sillapachaiyaporn
- Graduate Program in Clinical Biochemistry and Molecular Medicine, Department of Clinical Chemistry, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Siriporn Chuchawankul
- Immunomodulation of Natural Products Research Group, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, 10330, Thailand.,Department of Transfusion Medicine and Clinical Microbiology, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Tewin Tencomnao
- Immunomodulation of Natural Products Research Group, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, 10330, Thailand.,Department of Clinical Chemistry, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, 10330, Thailand
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17
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McClenaghan C, Hanson A, Lee SJ, Nichols CG. Coronavirus Proteins as Ion Channels: Current and Potential Research. Front Immunol 2020; 11:573339. [PMID: 33154751 PMCID: PMC7586316 DOI: 10.3389/fimmu.2020.573339] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 09/22/2020] [Indexed: 01/22/2023] Open
Abstract
Coronavirus (CoV) outbreaks have recently emerged as a global public health threat due to their exceptional zoonotic potential — a feature arising from their ability to infect a diverse range of potential hosts combined with their high capacity for mutation and recombination. After Severe Acute Respiratory Syndrome (SARS) CoV-1 in 2003 and Middle East Respiratory Syndrome (MERS) CoV in 2012, with the current SARS-CoV-2 pandemic we are now in the midst of the third deadly international CoV outbreak in less than 20 years. Coronavirus outbreaks present a critical threat to global public health and an urgent necessity for therapeutic options. Here, we critically examine the current evidence for ion channel activity in CoV proteins and the potential for modulation as a therapeutic approach.
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Affiliation(s)
- Conor McClenaghan
- Center for Investigation of Membrane Excitability Diseases, and Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO, United States
| | - Alex Hanson
- Center for Investigation of Membrane Excitability Diseases, and Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO, United States
| | - Sun-Joo Lee
- Center for Investigation of Membrane Excitability Diseases, and Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO, United States
| | - Colin G Nichols
- Center for Investigation of Membrane Excitability Diseases, and Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO, United States
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18
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Giri R, Bhardwaj T, Shegane M, Gehi BR, Kumar P, Gadhave K, Oldfield CJ, Uversky VN. Understanding COVID-19 via comparative analysis of dark proteomes of SARS-CoV-2, human SARS and bat SARS-like coronaviruses. Cell Mol Life Sci 2020; 78:1655-1688. [PMID: 32712910 PMCID: PMC7382329 DOI: 10.1007/s00018-020-03603-x] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 07/03/2020] [Accepted: 07/17/2020] [Indexed: 01/08/2023]
Abstract
The recently emerged coronavirus designated as SARS-CoV-2 (also known as 2019 novel coronavirus (2019-nCoV) or Wuhan coronavirus) is a causative agent of coronavirus disease 2019 (COVID-19), which is rapidly spreading throughout the world now. More than 1.21 million cases of SARS-CoV-2 infection and more than 67,000 COVID-19-associated mortalities have been reported worldwide till the writing of this article, and these numbers are increasing every passing hour. The World Health Organization (WHO) has declared the SARS-CoV-2 spread as a global public health emergency and admitted COVID-19 as a pandemic now. Multiple sequence alignment data correlated with the already published reports on SARS-CoV-2 evolution indicated that this virus is closely related to the bat severe acute respiratory syndrome-like coronavirus (bat SARS-like CoV) and the well-studied human SARS coronavirus (SARS-CoV). The disordered regions in viral proteins are associated with the viral infectivity and pathogenicity. Therefore, in this study, we have exploited a set of complementary computational approaches to examine the dark proteomes of SARS-CoV-2, bat SARS-like, and human SARS CoVs by analysing the prevalence of intrinsic disorder in their proteins. According to our findings, SARS-CoV-2 proteome contains very significant levels of structural order. In fact, except for nucleocapsid, Nsp8, and ORF6, the vast majority of SARS-CoV-2 proteins are mostly ordered proteins containing less intrinsically disordered protein regions (IDPRs). However, IDPRs found in SARS-CoV-2 proteins are functionally important. For example, cleavage sites in its replicase 1ab polyprotein are found to be highly disordered, and almost all SARS-CoV-2 proteins contains molecular recognition features (MoRFs), which are intrinsic disorder-based protein–protein interaction sites that are commonly utilized by proteins for interaction with specific partners. The results of our extensive investigation of the dark side of SARS-CoV-2 proteome will have important implications in understanding the structural and non-structural biology of SARS or SARS-like coronaviruses.
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Affiliation(s)
- Rajanish Giri
- School of Basic Sciences, Indian Institute of Technology Mandi, VPO Kamand, Mandi, Himachal Pradesh, 175005, India.
| | - Taniya Bhardwaj
- School of Basic Sciences, Indian Institute of Technology Mandi, VPO Kamand, Mandi, Himachal Pradesh, 175005, India
| | - Meenakshi Shegane
- School of Basic Sciences, Indian Institute of Technology Mandi, VPO Kamand, Mandi, Himachal Pradesh, 175005, India
| | - Bhuvaneshwari R Gehi
- School of Basic Sciences, Indian Institute of Technology Mandi, VPO Kamand, Mandi, Himachal Pradesh, 175005, India
| | - Prateek Kumar
- School of Basic Sciences, Indian Institute of Technology Mandi, VPO Kamand, Mandi, Himachal Pradesh, 175005, India
| | - Kundlik Gadhave
- School of Basic Sciences, Indian Institute of Technology Mandi, VPO Kamand, Mandi, Himachal Pradesh, 175005, India
| | | | - Vladimir N Uversky
- Department of Molecular Medicine, Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL, USA.,Laboratory of New Methods in Biology, Institute for Biological Instrumentation of the Russian Academy of Sciences, Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", Moscow region, Pushchino, 142290, Russia
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19
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Zhang Y, Zeng X, Jiao Y, Li Z, Liu Q, Ye J, Yang M. Mechanisms involved in the development of thrombocytopenia in patients with COVID-19. Thromb Res 2020; 193:110-115. [PMID: 32535232 PMCID: PMC7274097 DOI: 10.1016/j.thromres.2020.06.008] [Citation(s) in RCA: 80] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 05/29/2020] [Accepted: 06/02/2020] [Indexed: 01/08/2023]
Abstract
Corona Virus Disease 2019 (COVID-19) is caused by the novel coronavirus SARS-CoV-2. Emerging genetic and clinical evidence suggests similarities between COVID-19 patients and those with severe acute respiratory syndrome and Middle East respiratory syndrome. Hematological changes such as lymphopenia and thrombocytopenia are not rare in COVID-19 patients, and a smaller population of these patients had leukopenia. Thrombocytopenia was detected in 5–41.7% of the patients with COVID-19. Analyzing the dynamic decrease in platelet counts may be useful in the prognosis of patients with COVID-19. However, the mechanisms underlying the development of thrombocytopenia remain to be elucidated. This review summarizes the hematological changes in patients infected with SARS-CoV-2 and possible underlying mechanisms of thrombocytopenia development. Early diagnosis and treatment of COVID-19 patients can reduce mortality. There is no laboratory test index to predict disease progression and prognosis. Progressive decline in platelets may be a prognostic factor for COVID-19 patients. Monitoring platelet count may be an effective index for COVID-19 progression.
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Affiliation(s)
- Yujiao Zhang
- Department of Hematology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Xiaoyuan Zeng
- Department of Hematology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Yingying Jiao
- Department of Hematology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Zongpeng Li
- Department of Hematology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Qifa Liu
- Department of Hematology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Jieyu Ye
- Department of Hematology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China.
| | - Mo Yang
- The Seventh Affiliated Hospital, Sun Yat-sen University, Shenzhen, Guangdong 518107, China.
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20
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Chen IY, Moriyama M, Chang MF, Ichinohe T. Severe Acute Respiratory Syndrome Coronavirus Viroporin 3a Activates the NLRP3 Inflammasome. Front Microbiol 2019; 10:50. [PMID: 30761102 PMCID: PMC6361828 DOI: 10.3389/fmicb.2019.00050] [Citation(s) in RCA: 401] [Impact Index Per Article: 80.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Accepted: 01/14/2019] [Indexed: 12/14/2022] Open
Abstract
Nod-like receptor family, pyrin domain-containing 3 (NLRP3) regulates the secretion of proinflammatory cytokines interleukin 1 beta (IL-1β) and IL-18. We previously showed that influenza virus M2 or encephalomyocarditis virus (EMCV) 2B proteins stimulate IL-1β secretion following activation of the NLRP3 inflammasome. However, the mechanism by which severe acute respiratory syndrome coronavirus (SARS-CoV) activates the NLRP3 inflammasome remains unknown. Here, we provide direct evidence that SARS-CoV 3a protein activates the NLRP3 inflammasome in lipopolysaccharide-primed macrophages. SARS-CoV 3a was sufficient to cause the NLRP3 inflammasome activation. The ion channel activity of the 3a protein was essential for 3a-mediated IL-1β secretion. While cells uninfected or infected with a lentivirus expressing a 3a protein defective in ion channel activity expressed NLRP3 uniformly throughout the cytoplasm, NLRP3 was redistributed to the perinuclear space in cells infected with a lentivirus expressing the 3a protein. K+ efflux and mitochondrial reactive oxygen species were important for SARS-CoV 3a-induced NLRP3 inflammasome activation. These results highlight the importance of viroporins, transmembrane pore-forming viral proteins, in virus-induced NLRP3 inflammasome activation.
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Affiliation(s)
- I-Yin Chen
- Division of Viral Infection, Department of Infectious Disease Control, International Research Center for Infectious Diseases, Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Miyu Moriyama
- Division of Viral Infection, Department of Infectious Disease Control, International Research Center for Infectious Diseases, Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Ming-Fu Chang
- Institute of Biochemistry and Molecular Biology, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Takeshi Ichinohe
- Division of Viral Infection, Department of Infectious Disease Control, International Research Center for Infectious Diseases, Institute of Medical Science, The University of Tokyo, Tokyo, Japan
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21
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Teeravechyan S, Frantz PN, Wongthida P, Chailangkarn T, Jaru-Ampornpan P, Koonpaew S, Jongkaewwattana A. Deciphering the biology of porcine epidemic diarrhea virus in the era of reverse genetics. Virus Res 2016; 226:152-171. [PMID: 27212685 PMCID: PMC7114553 DOI: 10.1016/j.virusres.2016.05.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 05/04/2016] [Accepted: 05/04/2016] [Indexed: 01/01/2023]
Abstract
Emergence of the porcine epidemic diarrhea virus (PEDV) as a global threat to the swine industry underlies the urgent need for deeper understanding of this virus. To date, we have yet to identify functions for all the major gene products, much less grasp their implications for the viral life cycle and pathogenic mechanisms. A major reason is the lack of genetic tools for studying PEDV. In this review, we discuss the reverse genetics approaches that have been successfully used to engineer infectious clones of PEDV as well as other potential and complementary methods that have yet to be applied to PEDV. The importance of proper cell culture for successful PEDV propagation and maintenance of disease phenotype are addressed in our survey of permissive cell lines. We also highlight areas of particular relevance to PEDV pathogenesis and disease that have benefited from reverse genetics studies and pressing questions that await resolution by such studies. In particular, we examine the spike protein as a determinant of viral tropism, entry and virulence, ORF3 and its association with cell culture adaptation, and the nucleocapsid protein and its potential role in modulating PEDV pathogenicity. Finally, we conclude with an exploration of how reverse genetics can help mitigate the global impact of PEDV by addressing the challenges of vaccine development.
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Affiliation(s)
- Samaporn Teeravechyan
- Virology and Cell Technology Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathumthani, 12120 Thailand
| | - Phanramphoei Namprachan Frantz
- Virology and Cell Technology Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathumthani, 12120 Thailand
| | - Phonphimon Wongthida
- Virology and Cell Technology Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathumthani, 12120 Thailand
| | - Thanathom Chailangkarn
- Virology and Cell Technology Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathumthani, 12120 Thailand
| | - Peera Jaru-Ampornpan
- Virology and Cell Technology Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathumthani, 12120 Thailand
| | - Surapong Koonpaew
- Virology and Cell Technology Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathumthani, 12120 Thailand
| | - Anan Jongkaewwattana
- Virology and Cell Technology Laboratory, National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathumthani, 12120 Thailand.
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22
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The Emerging Roles of Viroporins in ER Stress Response and Autophagy Induction during Virus Infection. Viruses 2015; 7:2834-57. [PMID: 26053926 PMCID: PMC4488716 DOI: 10.3390/v7062749] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 05/27/2015] [Accepted: 05/29/2015] [Indexed: 01/14/2023] Open
Abstract
Viroporins are small hydrophobic viral proteins that oligomerize to form aqueous pores on cellular membranes. Studies in recent years have demonstrated that viroporins serve important functions during virus replication and contribute to viral pathogenicity. A number of viroporins have also been shown to localize to the endoplasmic reticulum (ER) and/or its associated membranous organelles. In fact, replication of most RNA viruses is closely linked to the ER, and has been found to cause ER stress in the infected cells. On the other hand, autophagy is an evolutionarily conserved "self-eating" mechanism that is also observed in cells infected with RNA viruses. Both ER stress and autophagy are also known to modulate a wide variety of signaling pathways including pro-inflammatory and innate immune response, thereby constituting a major aspect of host-virus interactions. In this review, the potential involvement of viroporins in virus-induced ER stress and autophagy will be discussed.
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Liu DX, Fung TS, Chong KKL, Shukla A, Hilgenfeld R. Accessory proteins of SARS-CoV and other coronaviruses. Antiviral Res 2014; 109:97-109. [PMID: 24995382 PMCID: PMC7113789 DOI: 10.1016/j.antiviral.2014.06.013] [Citation(s) in RCA: 292] [Impact Index Per Article: 29.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Revised: 06/17/2014] [Accepted: 06/23/2014] [Indexed: 01/21/2023]
Abstract
The huge RNA genome of SARS coronavirus comprises a number of open reading frames that code for a total of eight accessory proteins. Although none of these are essential for virus replication, some appear to have a role in virus pathogenesis. Notably, some SARS-CoV accessory proteins have been shown to modulate the interferon signaling pathways and the production of pro-inflammatory cytokines. The structural information on these proteins is also limited, with only two (p7a and p9b) having their structures determined by X-ray crystallography. This review makes an attempt to summarize the published knowledge on SARS-CoV accessory proteins, with an emphasis on their involvement in virus-host interaction. The accessory proteins of other coronaviruses are also briefly discussed. This paper forms part of a series of invited articles in Antiviral Research on "From SARS to MERS: 10 years of research on highly pathogenic human coronaviruses" (see Introduction by Hilgenfeld and Peiris (2013)).
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Affiliation(s)
- Ding Xiang Liu
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore.
| | - To Sing Fung
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Kelvin Kian-Long Chong
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Aditi Shukla
- Institute of Biochemistry, Center for Structural and Cell Biology in Medicine, University of Lübeck, Ratzeburger Allee 160, 23538 Lübeck, Germany; German Center for Infection Research (DZIF), University of Lübeck, Germany
| | - Rolf Hilgenfeld
- Institute of Biochemistry, Center for Structural and Cell Biology in Medicine, University of Lübeck, Ratzeburger Allee 160, 23538 Lübeck, Germany; German Center for Infection Research (DZIF), University of Lübeck, Germany
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24
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Yu CJ, Ko CJ, Hsieh CH, Chien CT, Huang LH, Lee CW, Jiang CC. Proteomic analysis of osteoarthritic chondrocyte reveals the hyaluronic acid-regulated proteins involved in chondroprotective effect under oxidative stress. J Proteomics 2014; 99:40-53. [PMID: 24480285 DOI: 10.1016/j.jprot.2014.01.016] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Revised: 01/09/2014] [Accepted: 01/15/2014] [Indexed: 02/06/2023]
Abstract
UNLABELLED Osteoarthritis (OA), the most common type of arthritis, is a degenerative joint disease. Oxidative stress is well known to play important roles in cartilage degradation and pathogenesis of OA. The intra-articular injection of hyaluronic acid (IAHA) is accepted as an effective clinical therapy for OA, but we do not yet fully understand the mechanisms underlying the effects of HA on OA chondrocytes under oxidative stress. Here, we show for the first time that IAHA significantly reduces the synovial fluid levels of hydrogen peroxide (H2O2) and superoxide (O2(-)) in patients with knee OA. We also demonstrate that HA suppresses H2O2-induced cell death in human OA chondrocytes. Proteomic approaches (2-DE combined with mass spectrometry) allowed us to identify 13 protein spots corresponding to 12 non-redundant proteins as HA-regulated proteins in OA chondrocytes under oxidative stress. The expression levels of three putative HA-regulated proteins (TALDO, ANXA1 and EF2) in control, H2O2-, HA- and HA/H2O2-treated OA chondrocytes were verified by Western blotting and the results indeed support the notion that HA acts in anti-oxidation, anti-apoptosis, and the promotion of cell survival. Our results collectively demonstrate the utility of proteomic approaches and provide new insights into the chondroprotective effects of HA on OA. BIOLOGICAL SIGNIFICANCE In the present study, we show for the first time that IAHA reduces the levels of H2O2 and O2(-) in synovial fluids from OA patients. We used primary cultured human OA chondrocytes as a model, treated cells with H2O2 to partly mimic their physiological conditions under oxidative stress, and examined the protection effects of HA. The proteomic approach allowed us to identify candidate proteins regulated by H2O2 and/or HA in OA chondrocytes. We found that proteins functioning in stress responses, apoptosis and protein synthesis were consistently regulated by HA in chondrocytes under oxidative stress. These novel results contribute to our understanding of the molecular mechanisms underlying HA-mediated chondroprotection.
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Affiliation(s)
- Chia-Jung Yu
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan; Department of Cell and Molecular Biology, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan; Molecular Medicine Research Center, Chang Gung University, Tao-Yuan, Taiwan.
| | - Chun-Jung Ko
- Graduate Institute of Biochemistry and Molecular Biology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Chang-Hsun Hsieh
- Department of Orthopaedic Surgery, National Taiwan University Hospital, National Taiwan University, Taipei, Taiwan
| | - Chiang-Ting Chien
- Department of Life Science, National Taiwan Normal University, Taipei, Taiwan
| | - Lien-Hung Huang
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan
| | - Chien-Wei Lee
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan
| | - Ching-Chuan Jiang
- Department of Orthopaedic Surgery, National Taiwan University Hospital, National Taiwan University, Taipei, Taiwan
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25
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Zhang R, Wang K, Lv W, Yu W, Xie S, Xu K, Schwarz W, Xiong S, Sun B. The ORF4a protein of human coronavirus 229E functions as a viroporin that regulates viral production. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1838:1088-95. [PMID: 23906728 PMCID: PMC7094429 DOI: 10.1016/j.bbamem.2013.07.025] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Revised: 07/12/2013] [Accepted: 07/18/2013] [Indexed: 12/29/2022]
Abstract
In addition to a set of canonical genes, coronaviruses encode additional accessory proteins. A locus located between the spike and envelope genes is conserved in all coronaviruses and contains a complete or truncated open reading frame (ORF). Previously, we demonstrated that this locus, which contains the gene for accessory protein 3a from severe acute respiratory syndrome coronavirus (SARS-CoV), encodes a protein that forms ion channels and regulates virus release. In the current study, we explored whether the ORF4a protein of HCoV-229E has similar functions. Our findings revealed that the ORF4a proteins were expressed in infected cells and localized at the endoplasmic reticulum/Golgi intermediate compartment (ERGIC). The ORF4a proteins formed homo-oligomers through disulfide bridges and possessed ion channel activity in both Xenopus oocytes and yeast. Based on the measurement of conductance to different monovalent cations, the ORF4a was suggested to form a non-selective channel for monovalent cations, although Li(+) partially reduced the inward current. Furthermore, viral production decreased when the ORF4a protein expression was suppressed by siRNA in infected cells. Collectively, this evidence indicates that the HCoV-229E ORF4a protein is functionally analogous to the SARS-CoV 3a protein, which also acts as a viroporin that regulates virus production. This article is part of a Special Issue entitled: Viral Membrane Proteins - Channels for Cellular Networking.
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Affiliation(s)
- Ronghua Zhang
- Jiangsu Key Laboratory of Infection and Immunity, Institutes of Biology and Medical Sciences, Soochow University, Suzhou 215123, China; Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200025, China
| | - Kai Wang
- Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200025, China
| | - Wei Lv
- Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200025, China
| | - Wenjing Yu
- Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200025, China
| | - Shiqi Xie
- Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200025, China
| | - Ke Xu
- Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200025, China
| | - Wolfgang Schwarz
- Goethe-University Frankfurt, Institute for Biophysics, Max-von-Laue-Str. 1, D-60438 Frankfurt am Main, Germany; Shanghai Research Center for Acupuncture and Meridian, 199 Guoshoujing Road, Shanghai 201023, China
| | - Sidong Xiong
- Jiangsu Key Laboratory of Infection and Immunity, Institutes of Biology and Medical Sciences, Soochow University, Suzhou 215123, China.
| | - Bing Sun
- Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200025, China; State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.
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26
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McBride R, Fielding BC. The role of severe acute respiratory syndrome (SARS)-coronavirus accessory proteins in virus pathogenesis. Viruses 2012. [PMID: 23202509 PMCID: PMC3509677 DOI: 10.3390/v4112902] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
A respiratory disease caused by a novel coronavirus, termed the severe acute respiratory syndrome coronavirus (SARS-CoV), was first reported in China in late 2002. The subsequent efficient human-to-human transmission of this virus eventually affected more than 30 countries worldwide, resulting in a mortality rate of ~10% of infected individuals. The spread of the virus was ultimately controlled by isolation of infected individuals and there has been no infections reported since April 2004. However, the natural reservoir of the virus was never identified and it is not known if this virus will re-emerge and, therefore, research on this virus continues. The SARS-CoV genome is about 30 kb in length and is predicted to contain 14 functional open reading frames (ORFs). The genome encodes for proteins that are homologous to known coronavirus proteins, such as the replicase proteins (ORFs 1a and 1b) and the four major structural proteins: nucleocapsid (N), spike (S), membrane (M) and envelope (E). SARS-CoV also encodes for eight unique proteins, called accessory proteins, with no known homologues. This review will summarize the current knowledge on SARS-CoV accessory proteins and will include: (i) expression and processing; (ii) the effects on cellular processes; and (iii) functional studies.
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Affiliation(s)
- Ruth McBride
- Anatomy Cluster, Department of Medical Biosciences, Faculty of Natural Sciences, University of the Western Cape, Private Bag X17, Modderdam Road, Bellville, Western Cape, 7535, South Africa;
| | - Burtram C. Fielding
- Molecular Biology and Virology Laboratory, Department of Medical Biosciences, Faculty of Natural Sciences, University of the Western Cape, Private Bag X17, Modderdam Road, Bellville, Western Cape, 7535, South Africa
- Author to whom correspondence should be addressed; ; Tel.: +27-21-959-3620; Fax: +27-21-959-3125
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27
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Fischer WB, Wang YT, Schindler C, Chen CP. Mechanism of function of viral channel proteins and implications for drug development. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2012; 294:259-321. [PMID: 22364876 PMCID: PMC7149447 DOI: 10.1016/b978-0-12-394305-7.00006-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Viral channel-forming proteins comprise a class of viral proteins which, similar to their host companions, are made to alter electrochemical or substrate gradients across lipid membranes. These proteins are active during all stages of the cellular life cycle of viruses. An increasing number of proteins are identified as channel proteins, but the precise role in the viral life cycle is yet unknown for the majority of them. This review presents an overview about these proteins with an emphasis on those with available structural information. A concept is introduced which aligns the transmembrane domains of viral channel proteins with those of host channels and toxins to give insights into the mechanism of function of the viral proteins from potential sequence identities. A summary of to date investigations on drugs targeting these proteins is given and discussed in respect of their mode of action in vivo.
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Affiliation(s)
- Wolfgang B. Fischer
- Institute of Biophotonics, School of Biomedical Science and Engineering, National Yang-Ming University, Taipei 112, Taiwan
| | - Yi-Ting Wang
- Institute of Biophotonics, School of Biomedical Science and Engineering, National Yang-Ming University, Taipei 112, Taiwan
| | - Christina Schindler
- Institute of Biophotonics, School of Biomedical Science and Engineering, National Yang-Ming University, Taipei 112, Taiwan
| | - Chin-Pei Chen
- Institute of Biophotonics, School of Biomedical Science and Engineering, National Yang-Ming University, Taipei 112, Taiwan
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28
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Müller MA, van der Hoek L, Voss D, Bader O, Lehmann D, Schulz AR, Kallies S, Suliman T, Fielding BC, Drosten C, Niedrig M. Human coronavirus NL63 open reading frame 3 encodes a virion-incorporated N-glycosylated membrane protein. Virol J 2010; 7:6. [PMID: 20078868 PMCID: PMC2819038 DOI: 10.1186/1743-422x-7-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2009] [Accepted: 01/15/2010] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Human pathogenic coronavirus NL63 (hCoV-NL63) is a group 1 (alpha) coronavirus commonly associated with respiratory tract infections. In addition to known non-structural and structural proteins all coronaviruses have one or more accessory proteins whose functions are mostly unknown. Our study focuses on hCoV-NL63 open reading frame 3 (ORF 3) which is a highly conserved accessory protein among coronaviruses. RESULTS In-silico analysis of the 225 amino acid sequence of hCoV-NL63 ORF 3 predicted a triple membrane-spanning protein. Expression in infected CaCo-2 and LLC-MK2 cells was confirmed by immunofluorescence and Western blot analysis. The protein was detected within the endoplasmatic reticulum/Golgi intermediate compartment (ERGIC) where coronavirus assembly and budding takes place. Subcellular localization studies using recombinant ORF 3 protein transfected in Huh-7 cells revealed occurrence in ERGIC, Golgi- and lysosomal compartments. By fluorescence microscopy of differently tagged envelope (E), membrane (M) and nucleocapsid (N) proteins it was shown that ORF 3 protein colocalizes extensively with E and M within the ERGIC. Using N-terminally FLAG-tagged ORF 3 protein and an antiserum specific to the C-terminus we verified the proposed topology of an extracellular N-terminus and a cytosolic C-terminus. By in-vitro translation analysis and subsequent endoglycosidase H digestion we showed that ORF 3 protein is N-glycosylated at the N-terminus. Analysis of purified viral particles revealed that ORF 3 protein is incorporated into virions and is therefore an additional structural protein. CONCLUSIONS This study is the first extensive expression analysis of a group 1 hCoV-ORF 3 protein. We give evidence that ORF 3 protein is a structural N-glycosylated and virion-incorporated protein.
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29
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Modulation of Host Cell Death by SARS Coronavirus Proteins. MOLECULAR BIOLOGY OF THE SARS-CORONAVIRUS 2010. [PMCID: PMC7176189 DOI: 10.1007/978-3-642-03683-5_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Both types of cell death, namely necrosis and apoptosis, are found in organs of SARS coronavirus (CoV) infected patients. The gastrointestinal tract, however, although also a target for SARS-CoV replication, is obviously not affected by cell death mechanisms. Such differences in cell death induction are paralleled by in-vitro studies. In a colon-derived cell line (Caco-2), proapoptotic proteins were down- and antiapoptotic proteins were upregulated during SARS-CoV infection. By contrast, in SARS-CoV infected Vero E6 cells, apoptosis was induced via the p38 MAPK and caspase dependent pathways. Both apoptotic pathways, although mostly the intrinsic signal transduction, can be targeted by structural as well as accessory proteins of SARS-CoV. The fact that all structural and most of the accessory proteins of SARS-CoV are implicated in apoptotic scenarios indicates the fundamental role of apoptosis in the SARS-CoV life cycle. Interestingly, at least for the nucleocapsid protein of SARS-CoV, a cell-type specific manipulation of apoptosis was confirmed.
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30
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The open reading frame 3a protein of severe acute respiratory syndrome-associated coronavirus promotes membrane rearrangement and cell death. J Virol 2009; 84:1097-109. [PMID: 19889773 DOI: 10.1128/jvi.01662-09] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The genome of the severe acute respiratory syndrome-associated coronavirus (SARS-CoV) contains eight open reading frames (ORFs) that encode novel proteins. These accessory proteins are dispensable for in vitro and in vivo replication and thus may be important for other aspects of virus-host interactions. We investigated the functions of the largest of the accessory proteins, the ORF 3a protein, using a 3a-deficient strain of SARS-CoV. Cell death of Vero cells after infection with SARS-CoV was reduced upon deletion of ORF 3a. Electron microscopy of infected cells revealed a role for ORF 3a in SARS-CoV induced vesicle formation, a prominent feature of cells from SARS patients. In addition, we report that ORF 3a is both necessary and sufficient for SARS-CoV-induced Golgi fragmentation and that the 3a protein accumulates and localizes to vesicles containing markers for late endosomes. Finally, overexpression of ADP-ribosylation factor 1 (Arf1), a small GTPase essential for the maintenance of the Golgi apparatus, restored Golgi morphology during infection. These results establish an important role for ORF 3a in SARS-CoV-induced cell death, Golgi fragmentation, and the accumulation of intracellular vesicles.
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31
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Lal SK, Xu K, Sun B. SARS Accessory Proteins ORF3a and 9b and Their Functional Analysis. MOLECULAR BIOLOGY OF THE SARS-CORONAVIRUS 2009. [PMCID: PMC7123986 DOI: 10.1007/978-3-642-03683-5_11] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The SARS coronavirus (CoV) positive-stranded RNA viral genome encodes 14 open reading frames (ORFs), eight of which encode proteins termed as “accessory proteins.” These proteins help the virus infect the host and promote virulence. In this chapter we describe some of our latest investigations into the structure and function of two such accessory proteins: ORF3a and 9b. The ORF3a accessory protein is the largest accessory protein in SARS-CoV and is a unique membrane protein consisting of three transmembrane domains. It colocalizes on the cell membrane and host Golgi networks and may be involved in ion channel formation during infection. Similarly the ORF9b accessory protein is 98 amino acids, associates with the spike and nucleocapsid proteins and has unusual membrane binding properties. In this chapter we have suggested possible new roles for these two accessory proteins which may in the long run contain answers to many unanswered questions and also give us new ideas for drugs and vaccine design.
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Affiliation(s)
- Sunil K. Lal
- Engineering & Biotechnology, International Centre for Genetic, Aruna Asaf Ali Marg, New Delhi, 110067 India
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32
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Abstract
Coronavirus genomes are single-stranded positive-sense RNA that are transcribed into a nested set of 3′ coterminal subgenomic RNAs for gene expression. Members of the Coronaviridae express canonical polymerase genes, as well as structural genes, including S, E, M, and N, but also express a highly divergent set of accessory genes whose open reading frames are interspersed among the structural genes within the 3′ one-third of the viral genome. The accessory genes are thought to contain “luxury” functions that are often not required for in-vitro virus replication. The severe acute respiratory syndrome coronavirus (SARS-CoV) expresses eight such accessory genes (ORF3a, -3b, -6, -7a, -7b, -8a, -8b, and -9b), the most of any known coronavirus. This chapter will review our current knowledge of expression, structure, and function of each of the SARS-CoV accessory genes.
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Affiliation(s)
- Sunil K. Lal
- Engineering & Biotechnology, International Centre for Genetic, Aruna Asaf Ali Marg, New Delhi, 110067 India
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33
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Chan CM, Tsoi H, Chan WM, Zhai S, Wong CO, Yao X, Chan WY, Tsui SKW, Chan HYE. The ion channel activity of the SARS-coronavirus 3a protein is linked to its pro-apoptotic function. Int J Biochem Cell Biol 2009; 41:2232-9. [PMID: 19398035 PMCID: PMC7108357 DOI: 10.1016/j.biocel.2009.04.019] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2008] [Revised: 03/12/2009] [Accepted: 04/20/2009] [Indexed: 01/15/2023]
Abstract
The severe acute respiratory syndrome-coronavirus (SARS-CoV) caused an outbreak of atypical pneumonia in 2003. The SARS-CoV viral genome encodes several proteins which have no homology to proteins in any other coronaviruses, and a number of these proteins have been implicated in viral cytopathies. One such protein is 3a, which is also known as X1, ORF3 and U274. 3a expression is detected in both SARS-CoV infected cultured cells and patients. Among the different functions identified, 3a is a capable of inducing apoptosis. We previously showed that caspase pathways are involved in 3a-induced apoptosis. In this study, we attempted to find out protein domains on 3a that are essential for its pro-apoptotic function. Protein sequence analysis reveals that 3a possesses three major protein signatures, the cysteine-rich, Yxx phi and diacidic domains. We showed that 3a proteins carrying respective mutations in these protein domains exhibit reduced pro-apoptotic activities, indicating the importance of these domains on 3a's pro-apoptotic function. It was previously reported that 3a possesses potassium ion channel activity. We further demonstrated that the blockade of 3a's potassium channel activity abolished caspase-dependent apoptosis. This report provides the first evidence that ion channel activity of 3a is required for its pro-apoptotic function. As ion channel activity has been reported to regulate apoptosis in different pathologic conditions, finding ways to modulate the ion channel activity may offer a new direction toward the inhibition of apoptosis triggered by SARS-CoV.
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Affiliation(s)
- Chak-Ming Chan
- Laboratory of Drosophila Research, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR, China
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34
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Severe acute respiratory syndrome coronavirus protein 6 accelerates murine hepatitis virus infections by more than one mechanism. J Virol 2008; 82:7212-22. [PMID: 18448520 DOI: 10.1128/jvi.02406-07] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The severe acute respiratory syndrome coronavirus (SARS-CoV) encodes numerous accessory proteins whose importance in the natural infection process is currently unclear. One of these accessory proteins is set apart by its function in the context of a related murine hepatitis virus (MHV) infection. SARS-CoV protein 6 increases MHV neurovirulence and accelerates MHV infection kinetics in tissue culture. Protein 6 also blocks nuclear import of macromolecules from the cytoplasm, a process known to involve its C-terminal residues interacting with cellular importins. In this study, protein 6 was expressed from plasmid DNAs and accumulated in cells prior to infection by wild-type MHV. Output of MHV progeny was significantly increased by preexisting protein 6. Protein 6 with C-terminal deletion mutations no longer interfered with nuclear import processes but still retained much of the capacity to augment MHV infections. However, some virus growth-enhancing activity could be ascribed to the C-terminal end of protein 6. To determine whether this augmentation provided by the C terminus was derived from interference with nuclear import, we evaluated the virus-modulating effects of small interfering RNAs (siRNAs) directed against importin-beta mRNAs, which down-regulated classical nuclear import pathways. The siRNAs did indeed prime cells for enhanced MHV infection. Our findings indicated that protein 6-mediated nuclear import blocks augmented MHV infections but is clearly not the only way that this accessory protein operates to create a milieu conducive to robust virus growth. Thus, the SARS-CoV protein 6 accelerates MHV infections by more than one mechanism.
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35
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Padhan K, Tanwar C, Hussain A, Hui PY, Lee MY, Cheung CY, Peiris JSM, Jameel S. Severe acute respiratory syndrome coronavirus Orf3a protein interacts with caveolin. J Gen Virol 2007; 88:3067-3077. [PMID: 17947532 DOI: 10.1099/vir.0.82856-0] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The orf3a (also called X1 or U274) gene is the largest unique open reading frame in the severe acute respiratory syndrome coronavirus genome and has been proposed to encode a protein with three transmembrane domains and a large cytoplasmic domain. Recent work has suggested that the 3a protein may play a structural role in the viral life cycle, although the mechanisms for this remain uncharacterized. Here, the expression of the 3a protein in various in vitro systems is shown, it has been localized to the Golgi region and its membrane topology in transfected cells has been confirmed. Three potential caveolin-1-binding sites were reported to be present in the 3a protein. By using various biochemical, biophysical and genetic techniques, interaction of the 3a protein with caveolin-1 is demonstrated. Any one of the potential sites in the 3a protein was sufficient for this interaction. These results are discussed with respect to the possible roles of the 3a protein in the viral life cycle.
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Affiliation(s)
- Kartika Padhan
- Virology Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi 110 067, India
| | - Charu Tanwar
- Virology Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi 110 067, India
| | - Amjad Hussain
- Virology Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi 110 067, India
| | - Pui Yan Hui
- Department of Microbiology, Queen Mary Hospital, University of Hong Kong, Hong Kong SAR
| | - Man Yan Lee
- Department of Microbiology, Queen Mary Hospital, University of Hong Kong, Hong Kong SAR
| | - Chung Yan Cheung
- Department of Microbiology, Queen Mary Hospital, University of Hong Kong, Hong Kong SAR
| | | | - Shahid Jameel
- Virology Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi 110 067, India
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36
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Le TM, Wong HH, Tay FPL, Fang S, Keng CT, Tan YJ, Liu DX. Expression, post-translational modification and biochemical characterization of proteins encoded by subgenomic mRNA8 of the severe acute respiratory syndrome coronavirus. FEBS J 2007; 274:4211-22. [PMID: 17645546 PMCID: PMC7164070 DOI: 10.1111/j.1742-4658.2007.05947.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The most striking difference between the subgenomic mRNA8 of severe acute respiratory syndrome coronavirus isolated from human and some animal species is the deletion of 29 nucleotides, resulting in splitting of a single ORF (ORF8) into two ORFs (ORF8a and ORF8b). ORF8a and ORF8b are predicted to encode two small proteins, 8a and 8b, and ORF8 a single protein, 8ab (a fusion form of 8a and 8b). To understand the functions of these proteins, we cloned cDNA fragments covering these ORFs into expression plasmids, and expressed the constructs in both in vitro and in vivo systems. Expression of a construct containing ORF8a and ORF8b generated only a single protein, 8a; no 8b protein expression was obtained. Expression of a construct containing ORF8 generated the 8ab fusion protein. Site‐directed mutagenesis and enzymatic treatment revealed that protein 8ab is modified by N‐linked glycosylation on the N81 residue and by ubiquitination. In the absence of the 8a region, protein 8b undergoes rapid degradation by proteasomes, and addition of proteasome inhibitors inhibits the degradation of protein 8b as well as the protein 8b‐induced rapid degradation of the severe acute respiratory syndrome coronavirus E protein. Glycosylation could also stabilize protein 8ab. More interestingly, the two proteins could bind to monoubiquitin and polyubiquitin, suggesting the potential involvement of these proteins in the pathogenesis of severe acute respiratory syndrome coronavirus.
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Affiliation(s)
- Tra M Le
- Department of Biological Sciences, National University of Singapore, Singapore
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37
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Kumar P, Gunalan V, Liu B, Chow VT, Druce J, Birch C, Catton M, Fielding BC, Tan YJ, Lal SK. The nonstructural protein 8 (nsp8) of the SARS coronavirus interacts with its ORF6 accessory protein. Virology 2007; 366:293-303. [PMID: 17532020 PMCID: PMC7103355 DOI: 10.1016/j.virol.2007.04.029] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2007] [Revised: 03/14/2007] [Accepted: 04/21/2007] [Indexed: 12/14/2022]
Abstract
Severe acute respiratory syndrome (SARS) coronavirus (SARS-CoV) caused a severe outbreak in several regions of the world in 2003. The SARS-CoV genome is predicted to contain 14 functional open reading frames (ORFs). The first ORF (1a and 1b) encodes a large polyprotein that is cleaved into nonstructural proteins (nsp). The other ORFs encode for four structural proteins (spike, membrane, nucleocapsid and envelope) as well as eight SARS-CoV-specific accessory proteins (3a, 3b, 6, 7a, 7b, 8a, 8b and 9b). In this report we have cloned the predicted nsp8 gene and the ORF6 gene of the SARS-CoV and studied their abilities to interact with each other. We expressed the two proteins as fusion proteins in the yeast two-hybrid system to demonstrate protein-protein interactions and tested the same using a yeast genetic cross. Further the strength of the interaction was measured by challenging growth of the positive interaction clones on increasing gradients of 2-amino trizole. The interaction was then verified by expressing both proteins separately in-vitro in a coupled-transcription translation system and by coimmunoprecipitation in mammalian cells. Finally, colocalization experiments were performed in SARS-CoV infected Vero E6 mammalian cells to confirm the nsp8-ORF6 interaction. To the best of our knowledge, this is the first report of the interaction between a SARS-CoV accessory protein and nsp8 and our findings suggest that ORF6 protein may play a role in virus replication.
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Affiliation(s)
- Purnima Kumar
- Virology Group, International Centre for Genetic Engineering and Biotechnology, P. O. Box: 10504, Aruna Asaf Ali Road, New Delhi 110067, India
| | - Vithiagaran Gunalan
- Collaborative Anti-Viral Research Group, Institute of Molecular and Cell Biology, 61 Biopolis Drive, Proteos, Singapore 138673, Singapore
| | - Boping Liu
- Microbiology Department, National University of Singapore, Kent Ridge, Singapore 117597, Singapore
| | - Vincent T.K. Chow
- Microbiology Department, National University of Singapore, Kent Ridge, Singapore 117597, Singapore
| | - Julian Druce
- Victorian Infectious Diseases Reference Laboratory, North Melbourne, Victoria, Australia
| | - Chris Birch
- Victorian Infectious Diseases Reference Laboratory, North Melbourne, Victoria, Australia
| | - Mike Catton
- Victorian Infectious Diseases Reference Laboratory, North Melbourne, Victoria, Australia
| | - Burtram C. Fielding
- Collaborative Anti-Viral Research Group, Institute of Molecular and Cell Biology, 61 Biopolis Drive, Proteos, Singapore 138673, Singapore
| | - Yee-Joo Tan
- Collaborative Anti-Viral Research Group, Institute of Molecular and Cell Biology, 61 Biopolis Drive, Proteos, Singapore 138673, Singapore
| | - Sunil K. Lal
- Virology Group, International Centre for Genetic Engineering and Biotechnology, P. O. Box: 10504, Aruna Asaf Ali Road, New Delhi 110067, India
- Corresponding author. Fax: +91 11 26162316.
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Yuan X, Yao Z, Wu J, Zhou Y, Shan Y, Dong B, Zhao Z, Hua P, Chen J, Cong Y. G1 phase cell cycle arrest induced by SARS-CoV 3a protein via the cyclin D3/pRb pathway. Am J Respir Cell Mol Biol 2007; 37:9-19. [PMID: 17413032 DOI: 10.1165/rcmb.2005-0345rc] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
SARS-CoV 3a is a structural protein, mainly localizing to Golgi apparatus and co-localizing with SARS-CoV M in co-transfected cells. Here we observed that transient expression of 3a inhibited cell growth and prevented 5-bromodeoxyuridine incorporation, suggesting that 3a deregulated cell cycle progression. Cell cycle analysis demonstrated that 3a expression was associated with blockage of cell cycle progression at G1 phase in HEK 293, COS-7, and Vero cells 24-60 h after transfection. Mutation analysis of 3a revealed that C-terminal region (176 aa approximately 274 aa), including a potential calcium ATPase motif, was essential for induction of cell cycle arrest. Topological analysis showed that 3a predominantly located in Golgi apparatus, with its N-terminus residing in the lumen (Nlum) and C-terminus in the cytosol (Ccyt). Analyzing the cellular proteins involving in regulation of cell cycle progression, we demonstrated that 3a expression was correlated with a significant reduction of cyclin D3 level and phosphorylation of retinoblastoma (Rb) protein at Ser-795 and Ser-809/811, not with the expression of cyclin D1, D2, cdk4, and cdk6 in 293 cells. Increases in p53 phosphorylation on Ser-15 were observed in both SARS-CoV M and 3a transfected cells, suggesting that it might not correlate with the 3a-induced G0/G1 phase arrest. The reduction of cyclin D3 level and phosphorylation of Rb were further confirmed in SARS-CoV infected Vero cells. These results indicate that SARS-CoV 3a protein, through limiting the expression of cyclin D3, may inhibit Rb phosphorylation, which in turn leads to a block in the G1 phase of the cell cycle and an inhibition of cell proliferation.
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Affiliation(s)
- Xiaoling Yuan
- Department of Pathophysiology, Beijing Institute of Radiation Medicine, No. 27 Taiping Road, Beijing 100850, China
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39
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Huang C, Narayanan K, Ito N, Peters CJ, Makino S. Severe acute respiratory syndrome coronavirus 3a protein is released in membranous structures from 3a protein-expressing cells and infected cells. J Virol 2007; 80:210-7. [PMID: 16352545 PMCID: PMC1317539 DOI: 10.1128/jvi.80.1.210-217.2006] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Severe acute respiratory syndrome coronavirus (SCoV) accessory protein 3a is a virus structural protein. We demonstrate here that 3a protein was released efficiently in membranous structures from various cell lines expressing 3a protein. A subpopulation of the released 3a protein is associated with detergent-resistant membranes. The presence of the YxxPhi and diacidic motifs, located within the cytoplasmic tail of the 3a protein, was not required for its efficient release. Analysis of supernatant from SCoV-infected cells with sucrose gradient sedimentation and virus capture assay indicated that the 3a protein was released from infected cells in two distinct populations, as a component of SCoV particles, and in membrane structures with a lower buoyant density. These data provide new insights into the biological properties of SCoV 3a protein.
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Affiliation(s)
- Cheng Huang
- Department of Microbiology and Immunology, The University of Texas Medical Branch at Galveston, Galveston, TX 77555-1019, USA
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40
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Khan S, Ng ML, Tan YJ. Expression of the severe acute respiratory syndrome coronavirus 3a protein and the assembly of coronavirus-like particles in the baculovirus expression system. Methods Mol Biol 2007; 379:35-50. [PMID: 17502669 PMCID: PMC7120620 DOI: 10.1007/978-1-59745-393-6_3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The Bac-to-Bac Baculovirus expression system was used to generate a recombinant baculovirus capable of expressing the severe acute respiratory syndrome (SARS)-coronavirus (CoV) 3a protein. Using the same expression system, two structural proteins, membrane (M) and envelope (E), were co-expressed to form SARS-CoV virus-like particles (VLPs) within an insect cell. Expression of viral proteins was confirmed by Western blot analysis and the formation of VLPs was studied by transmission electron microscopy.
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Affiliation(s)
- Sehaam Khan
- Collaborative Antiviral Research Group, Institute of Molecular and Cell Biology, Proteos, Singapore
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41
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Abstract
Severe acute respiratory syndrome (SARS) is caused by a coronavirus (CoV), SARSCoV. SARS-CoV belongs to the family Coronaviridae, which are enveloped RNA viruses in the order Nidovirales. Global research efforts are continuing to increase the understanding of the virus, the pathogenesis of the disease it causes (SARS), and the “heterogeneity of individual infectiousness” as well as shedding light on how to prepare for other emerging viral diseases. Promising drugs and vaccines have been identified. The milestones achieved have resulted from a truly international effort. Molecular studies dissected the adaptation of this virus as it jumped from an intermediary animal, the civet, to humans, thus providing valuable insights into processes of molecular emergence.
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Affiliation(s)
- Tommy R Tong
- Department of Pathology, Princess Margaret Hospital, Laichikok, Kowloon, Hong Kong, China
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42
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Åkerström S, Mirazimi A, Tan YJ. Inhibition of SARS-CoV replication cycle by small interference RNAs silencing specific SARS proteins, 7a/7b, 3a/3b and S. Antiviral Res 2006; 73:219-27. [PMID: 17112601 PMCID: PMC7114101 DOI: 10.1016/j.antiviral.2006.10.008] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2006] [Revised: 10/09/2006] [Accepted: 10/17/2006] [Indexed: 01/15/2023]
Abstract
The severe acute respiratory syndrome coronavirus (SARS CoV) genome has 14 potential open reading frames (ORFs). The first ORF is translated from the full-length genomic mRNA while the remaining ORFs are translated from eight subgeomic RNAs (sgRNAs). In this study, we designed small interference RNAs (siRNAs) targeting sgRNA 2, 3 and 7 and tested their efficiency and specificity in silencing the protein translated from the targeted sgRNA. Our results demonstrated that siRNA 7 could inhibit sgRNA 7, which showed 19/19 nucleotides (nt) matching, and sgRNA 8, which showed 18/19 nt matching; but, it did not inhibit the full-length genomic mRNA which showed 17/19 nt matching. Overall, each of the siRNAs can inhibit the targeted sgRNA without affecting the full-length genomic mRNA or the other sgRNAs that showed mismatch of two or more nt. Thus, siRNA could be designed so as to knockdown the expression of viral protein(s) from a targeted sgRNA during viral infection, thereby allowing the contribution of individual viral proteins to viral infection to be delineated. When Vero E6 cells expressing siRNA 2, 3 or 7 were infected with SARS-CoV, a significant reduction in the yield of progeny virus was observed. Indirect immunofluorescence assays showed that in the infected cells expressing each of the siRNAs, there was aspecific silencing of S, 3a and 7a, respectively, but the expression of nucleocapsid protein was not affected. Thus, our data suggests that the accessory proteins, i.e. 3a and 7a, could play an important role during the replication cycle of the SARS-CoV.
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Affiliation(s)
- Sara Åkerström
- Center for Microbiological Preparedness, Swedish Institute for Infectious Disease Control, SE-171 82 Solna, Sweden
| | - Ali Mirazimi
- Center for Microbiological Preparedness, Swedish Institute for Infectious Disease Control, SE-171 82 Solna, Sweden
- Corresponding author. Tel.: +46 8 457 25 73; fax: +46 8 30 79 57.
| | - Yee-Joo Tan
- Institute of Molecular and Cell Biology, 61 Biopolis Drive, 138673 Singapore, Singapore
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43
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Khan S, Fielding BC, Tan TH, Chou CF, Shen S, Lim SG, Hong W, Tan YJ. Over-expression of severe acute respiratory syndrome coronavirus 3b protein induces both apoptosis and necrosis in Vero E6 cells. Virus Res 2006; 122:20-7. [PMID: 16965829 PMCID: PMC7114230 DOI: 10.1016/j.virusres.2006.06.005] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2006] [Revised: 05/24/2006] [Accepted: 06/07/2006] [Indexed: 12/21/2022]
Abstract
The genome of the severe acute respiratory syndrome coronavirus encodes for eight accessory viral proteins with no known homologues in other coronaviruses. One of these is the 3b protein, which is encoded by the second open reading frame in subgenomic RNA 3 and contains 154 amino acids. Here, a detailed time-course study was performed to compare the apoptosis and necrosis profiles induced by full-length 3b, a 3b mutant that was deleted by 30 amino acids from the C terminus (3bΔ124-154) and the classical apoptosis inducer, Bax. Our results showed that Vero E6 cells transfected with a construct for expressing 3b underwent necrosis as early as 6 h after transfection and underwent simultaneous necrosis and apoptosis at later time-points. At all the time-points analysed, the apoptosis induced by the expression of 3b was less than the level induced by Bax but the level of necrosis was comparable. The 3bΔ124-154 mutant behaves in a similar manner indicating that the localization of the 3b protein does not seems to be important for the cell-death pathways since full-length 3b is localized predominantly to the nucleolus, while the mutant is found to be concentrated in the peri-nuclear regions. To our knowledge, this is the first report of the induction of necrosis by a SARS-CoV protein.
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Affiliation(s)
| | | | | | | | | | | | | | - Yee-Joo Tan
- Corresponding author. Tel.: +65 65869625; fax: +65 67791117.
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44
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Huang C, Ito N, Tseng CTK, Makino S. Severe acute respiratory syndrome coronavirus 7a accessory protein is a viral structural protein. J Virol 2006; 80:7287-94. [PMID: 16840309 PMCID: PMC1563709 DOI: 10.1128/jvi.00414-06] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Severe acute respiratory syndrome coronavirus (SCoV) 7a protein is one of the viral accessory proteins. In expressing cells, 7a protein exhibits a variety of biological activities, including induction of apoptosis, activation of the mitogen-activated protein kinase signaling pathway, inhibition of host protein translation, and suppression of cell growth progression. Analysis of SCoV particles that were purified by either sucrose gradient equilibrium centrifugation or a virus capture assay, in which intact SCoV particles were specifically immunoprecipitated by anti-S protein monoclonal antibody, demonstrated that 7a protein was associated with purified SCoV particles. Coexpression of 7a protein with SCoV S, M, N, and E proteins resulted in production of virus-like particles (VLPs) carrying 7a protein, while 7a protein was not released from cells expressing 7a protein alone. Although interaction between 7a protein and another SCoV accessory protein, 3a, has been reported, 3a protein was dispensable for assembly of 7a protein into VLPs. S protein was not required for the 7a protein incorporation into VLPs, and yet 7a protein interacted with S protein in coexpressing cells. These data established that, in addition to 3a protein, 7a protein was a SCoV accessory protein identified as a SCoV structural protein.
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Affiliation(s)
- Cheng Huang
- Department of Microbiology and Immunology, The University of Texas Medical Branch at Galveston, Galveston, TX 77555-1019, USA
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45
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Lu W, Zheng BJ, Xu K, Schwarz W, Du L, Wong CKL, Chen J, Duan S, Deubel V, Sun B. Severe acute respiratory syndrome-associated coronavirus 3a protein forms an ion channel and modulates virus release. Proc Natl Acad Sci U S A 2006; 103:12540-5. [PMID: 16894145 PMCID: PMC1567914 DOI: 10.1073/pnas.0605402103] [Citation(s) in RCA: 221] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Fourteen ORFs have been identified in the severe acute respiratory syndrome-associated coronavirus (SARS-CoV) genome. ORF 3a of SARS-CoV codes for a recently identified transmembrane protein, but its function remains unknown. In this study we confirmed the 3a protein expression and investigated its localization at the surface of SARS-CoV-infected or 3a-cDNA-transfected cells. Our experiments showed that recombinant 3a protein can form a homotetramer complex through interprotein disulfide bridges in 3a-cDNA-transfected cells, providing a clue to ion channel function. The putative ion channel activity of this protein was assessed in 3a-complement RNA-injected Xenopus oocytes by two-electrode voltage clamp. The results suggest that 3a protein forms a potassium sensitive channel, which can be efficiently inhibited by barium. After FRhK-4 cells were transfected with an siRNA, which is known to suppress 3a expression, followed by infection with SARS-CoV, the released virus was significantly decreased, whereas the replication of the virus in the infected cells was not changed. Our observation suggests that SARS-CoV ORF 3a functions as an ion channel that may promote virus release. This finding will help to explain the highly pathogenic nature of SARS-CoV and to develop new strategies for treatment of SARS infection.
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Affiliation(s)
- Wei Lu
- *Laboratory of Molecular Virology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, 225 South Chongqing Road, Shanghai 200025, China
- Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology
- Max Planck Guest Laboratory, and
| | - Bo-Jian Zheng
- Department of Microbiology, University of Hong Kong and Queen Mary Hospital, Hong Kong, China; and
| | - Ke Xu
- *Laboratory of Molecular Virology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, 225 South Chongqing Road, Shanghai 200025, China
- Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology
| | - Wolfgang Schwarz
- Max Planck Guest Laboratory, and
- Max Planck Institute for Biophysics, Max-von-Laue-Strasse 3, 60438 Frankfurt/M, Germany
| | - Lanying Du
- Department of Microbiology, University of Hong Kong and Queen Mary Hospital, Hong Kong, China; and
| | - Charlotte K. L. Wong
- Department of Microbiology, University of Hong Kong and Queen Mary Hospital, Hong Kong, China; and
| | - Jiadong Chen
- **Shanghai Institute of Neuroscience, Shanghai Institute of Biological Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Shuming Duan
- **Shanghai Institute of Neuroscience, Shanghai Institute of Biological Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Vincent Deubel
- *Laboratory of Molecular Virology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, 225 South Chongqing Road, Shanghai 200025, China
| | - Bing Sun
- *Laboratory of Molecular Virology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, 225 South Chongqing Road, Shanghai 200025, China
- Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology
- To whom correspondence should be sent at the ∗ address. E-mail:
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46
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Åkerström S, Tan YJ, Mirazimi A. Amino acids 15-28 in the ectodomain of SARS coronavirus 3a protein induces neutralizing antibodies. FEBS Lett 2006; 580:3799-803. [PMID: 16781713 PMCID: PMC7094653 DOI: 10.1016/j.febslet.2006.06.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2006] [Revised: 05/29/2006] [Accepted: 06/01/2006] [Indexed: 12/13/2022]
Abstract
A synthetic peptide corresponding to amino acids (aa) 15–28 of the severe acute respiratory syndrome coronavirus (SARS‐CoV) 3a protein was used to raise polyclonal antibodies in rabbits. This anti‐3a N‐terminal antibody could detect 3a protein in infected cells, as did an anti‐3a C‐terminal antibody previously described. The latter targeted the C‐terminal cytoplasmic domain of 3a (aa 134–274). The anti‐3a N‐terminal antibody could detect intracellular 3a as well as 3a expressed on the cell surface. Interestingly, only the anti‐3a N‐terminal antibody can inhibit SARS‐CoV propagation in Vero E6 culture although the binding affinity of the anti‐3a N‐terminal antibody was lower than the anti‐3a C‐terminal antibody.
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Affiliation(s)
- Sara Åkerström
- Center for Microbiological Preparedness, Swedish Institute for Infectious Disease Control, SE-171 82 Solna, Sweden
| | - Yee-Joo Tan
- Institute of Molecular and Cell Biology, CAVR, 61 Biopolis Drive, Singapore 138673, Singapore
| | - Ali Mirazimi
- Center for Microbiological Preparedness, Swedish Institute for Infectious Disease Control, SE-171 82 Solna, Sweden
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47
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Tan YJ, Lim SG, Hong W. Understanding the accessory viral proteins unique to the severe acute respiratory syndrome (SARS) coronavirus. Antiviral Res 2006; 72:78-88. [PMID: 16820226 PMCID: PMC7114237 DOI: 10.1016/j.antiviral.2006.05.010] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2006] [Revised: 04/29/2006] [Accepted: 05/15/2006] [Indexed: 12/14/2022]
Abstract
A novel coronavirus, termed the severe acute respiratory syndrome coronavirus (SARS-CoV), infected humans in Guangdong, China, in November 2002 and the subsequent efficient human-to-human transmissions of this virus caused profound disturbances in over 30 countries worldwide in 2003. Eventually, this epidemic was controlled by isolation and there has been no human infection reported since January 2004. However, research on different aspects of the SARS-CoV is not waning, as it is not known if this virus will re-emerge, especially since its origins and potential reservoir(s) are unresolved. The SARS-CoV genome is nearly 30 kb in length and contains 14 potential open reading frames (ORFs). Some of these ORFs encode for genes that are homologous to proteins found in all known coronaviruses, namely the replicase genes (ORFs 1a and 1b) and the four structural proteins: nucleocapsid, spike, membrane and envelope, and these proteins are expected to be essential for the replication of the virus. The remaining eight ORFs encodes for accessory proteins, varying in length from 39 to 274 amino acids, which are unique to SARS-CoV. This review will summarize the expeditious research on these accessory viral proteins in three major areas: (i) the detection of antibodies against accessory proteins in the serum of infected patients, (ii) the expression, processing and cellular localization of the accessory proteins, and (iii) the effects of the accessory proteins on cellular functions. These in-depth molecular and biochemical characterizations of the SARS-CoV accessory proteins, which have no homologues in other coronaviruses, may offer clues as to why the SARS-CoV causes such a severe and rapid attack in humans, while other coronaviruses that infect humans seem to be more forgiving.
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Affiliation(s)
- Yee-Joo Tan
- Institute of Molecular and Cell Biology, 61 Biopolis Drive, Proteos, Singapore 138673, Singapore.
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48
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Zhong X, Guo Z, Yang H, Peng L, Xie Y, Wong TY, Lai ST, Guo Z. Amino terminus of the SARS coronavirus protein 3a elicits strong, potentially protective humoral responses in infected patients. J Gen Virol 2006; 87:369-373. [PMID: 16432024 DOI: 10.1099/vir.0.81078-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The 3a protein of severe acute respiratory syndrome (SARS)-associated coronavirus is expressed and transported to the plasma membrane in tissue cells of infected patients. Its short N-terminal ectodomain was found to elicit strong humoral responses in half of the patients who had recovered from SARS. The ectodomain-specific antibodies from the convalescent-phase plasma readily recognized and induced destruction of 3a-expressing cells in the presence of the human complement system, demonstrating their potential ability to provide immune protection by recognizing and eliminating SARS coronavirus-infected cells that express the target protein. In addition, when coupled to a carrier protein, the ectodomain peptide elicited 3a-specific antibodies in mice and rabbit at high titres. These results showed that the N terminus of the 3a protein is highly immunogenic and elicits potentially protective humoral responses in infected patients. Therefore, the short extracellular domain may be a valuable immunogen in the development of a vaccine for infectious SARS.
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Affiliation(s)
- Xiaofen Zhong
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China
| | - Zufeng Guo
- Biotechnology Research Institute, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China
| | - Huanghao Yang
- Biotechnology Research Institute, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China
| | - Lisheng Peng
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China
| | - Yong Xie
- Department of Biology, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China
| | - Tin-Yau Wong
- Princess Margaret Hospital, Hong Kong SAR, China
| | - Sik-To Lai
- Princess Margaret Hospital, Hong Kong SAR, China
| | - Zhihong Guo
- Biotechnology Research Institute, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China
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49
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Oostra M, de Haan CAM, de Groot RJ, Rottier PJM. Glycosylation of the severe acute respiratory syndrome coronavirus triple-spanning membrane proteins 3a and M. J Virol 2006; 80:2326-36. [PMID: 16474139 PMCID: PMC1395384 DOI: 10.1128/jvi.80.5.2326-2336.2006] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The severe acute respiratory syndrome coronavirus (SARS-CoV) open reading frame 3a protein has recently been shown to be a structural protein. The protein is encoded by one of the so-called group-specific genes and has no sequence homology with any of the known structural or group-specific proteins of coronaviruses. It does, however, have several similarities to the coronavirus M proteins; (i) they are triple membrane spanning with the same topology, (ii) they have similar intracellular localizations (predominantly Golgi), (iii) both are viral structural proteins, and (iv) they appear to interact with the E and S proteins, as well as with each other. The M protein plays a crucial role in coronavirus assembly and is glycosylated in all coronaviruses, either by N-linked or by O-linked oligosaccharides. The conserved glycosylation of the coronavirus M proteins and the resemblance of the 3a protein to them led us to investigate the glycosylation of these two SARS-CoV membrane proteins. The proteins were expressed separately using the vaccinia virus T7 expression system, followed by metabolic labeling. Pulse-chase analysis showed that both proteins were modified, although in different ways. While the M protein acquired cotranslationally oligosaccharides that could be removed by PNGaseF, the 3a protein acquired its modifications posttranslationally, and they were not sensitive to the N-glycosidase enzyme. The SARS-CoV 3a protein, however, was demonstrated to contain sialic acids, indicating the presence of oligosaccharides. O-glycosylation of the 3a protein was indeed confirmed using an in situ O-glycosylation assay of endoplasmic reticulum-retained mutants. In addition, we showed that substitution of serine and threonine residues in the ectodomain of the 3a protein abolished the addition of the O-linked sugars. Thus, the SARS-CoV 3a protein is an O-glycosylated glycoprotein, like the group 2 coronavirus M proteins but unlike the SARS-CoV M protein, which is N glycosylated.
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Affiliation(s)
- M Oostra
- Virology Division, Department of Infectious Diseases and Immunology, Utrecht University, The Netherlands
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50
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Abstract
The previous epidemic of severe acute respiratory syndrome (SARS) has ended. However, many questions concerning how the aetiological agent, the novel SARS coronavirus (CoV), causes illness in humans remain unanswered. The pathology of fatal cases of SARS is dominated by diffuse alveolar damage. Specific histological changes are not detected in other organs. These contrast remarkably with the clinical picture, in which there are apparent manifestations in multiple organs. Both pathogen and host factors are important in the pathogenesis of SARS. The choice of specific receptors and the unique genome of the SARS‐CoV are important elements in understanding the biology of the pathogen. For the host cells, the outcome of SARS‐CoV infection, whether there are cytopathic effects or not, depends on the cell types that are infected. At the whole‐body level, immune‐mediated damage, due to activation of cytokines and/or chemokines and, perhaps, autoimmunity, may play key roles in the clinical and pathological features of SARS. Continued research is still required to determine the pathogenetic mechanisms involved and to combat this new emerging human infectious disease. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
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Affiliation(s)
- Anthony WI Lo
- Department of Anatomical and Cellular Pathology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong SAR, China
| | - Nelson LS Tang
- Department of Chemical Pathology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong SAR, China
- Center of Emerging Infectious Diseases, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong SAR, China
| | - Ka‐Fai To
- Department of Anatomical and Cellular Pathology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong SAR, China
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