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Townsend JA, Fapohunda O, Wang Z, Pham H, Taylor MT, Kloss B, Ho Park S, Opella S, Aspinwall CA, Marty MT. Differences in Oligomerization of the SARS-CoV-2 Envelope Protein, Poliovirus VP4, and HIV Vpu. Biochemistry 2024; 63:241-250. [PMID: 38216552 PMCID: PMC10872257 DOI: 10.1021/acs.biochem.3c00437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2024]
Abstract
Viroporins constitute a class of viral membrane proteins with diverse roles in the viral life cycle. They can self-assemble and form pores within the bilayer that transport substrates, such as ions and genetic material, that are critical to the viral infection cycle. However, there is little known about the oligomeric state of most viroporins. Here, we use native mass spectrometry in detergent micelles to uncover the patterns of oligomerization of the full-length SARS-CoV-2 envelope (E) protein, poliovirus VP4, and HIV Vpu. Our data suggest that the E protein is a specific dimer, VP4 is exclusively monomeric, and Vpu assembles into a polydisperse mixture of oligomers under these conditions. Overall, these results revealed the diversity in the oligomerization of viroporins, which has implications for the mechanisms of their biological functions as well as their potential as therapeutic targets.
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Affiliation(s)
- Julia A. Townsend
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
| | - Oluwaseun Fapohunda
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
| | - Zhihan Wang
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
| | - Hieu Pham
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
| | - Michael T. Taylor
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
| | - Brian Kloss
- New York Consortium on Membrane Protein Structure, New York Structural Biology Center, New York, NY 10027, USA
| | - Sang Ho Park
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA
| | - Stanley Opella
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA
| | - Craig A. Aspinwall
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
- Bio5 Institute, The University of Arizona, Tucson, Arizona 85721, United States
| | - Michael T. Marty
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
- Bio5 Institute, The University of Arizona, Tucson, Arizona 85721, United States
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Townsend JA, Fapohunda O, Wang Z, Pham H, Taylor MT, Kloss B, Park SH, Opella S, Aspinwall CA, Marty MT. Differences in Oligomerization of the SARS-CoV-2 Envelope Protein, Poliovirus VP4, and HIV Vpu. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.18.553902. [PMID: 37645758 PMCID: PMC10462163 DOI: 10.1101/2023.08.18.553902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Viroporins constitute a class of viral membrane proteins with diverse roles in the viral life cycle. They can self-assemble and form pores within the bilayer that transport substrates, such as ions and genetic material, that are critical to the viral infection cycle. However, there is little known about the oligomeric state of most viroporins. Here, we use native mass spectrometry (MS) in detergent micelles to uncover the patterns of oligomerization of the full-length SARS-CoV-2 envelope (E) protein, poliovirus VP4, and HIV Vpu. Our data suggest that the E protein is a specific dimer, VP4 is exclusively monomeric, and Vpu assembles into a polydisperse mixture of oligomers under these conditions. Overall, these results revealed the diversity in the oligomerization of viroporins, which has implications for mechanisms of their biological functions as well as their potential as therapeutic targets.
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Affiliation(s)
- Julia A. Townsend
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
| | - Oluwaseun Fapohunda
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
| | - Zhihan Wang
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
| | - Hieu Pham
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
| | - Michael T. Taylor
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
| | - Brian Kloss
- New York Consortium on Membrane Protein Structure, New York Structural Biology Center, New York, NY 10027, USA
| | - Sang Ho Park
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA
| | - Stanley Opella
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA
| | - Craig A. Aspinwall
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
- Bio5 Institute, The University of Arizona, Tucson, Arizona 85721, United States
| | - Michael T. Marty
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
- Bio5 Institute, The University of Arizona, Tucson, Arizona 85721, United States
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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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Rouka E, Gourgoulianis KI, Zarogiannis SG. In silico investigation of the viroporin E as a vaccine target against SARS-CoV-2. Am J Physiol Lung Cell Mol Physiol 2021; 320:L1057-L1063. [PMID: 33822639 PMCID: PMC8203416 DOI: 10.1152/ajplung.00443.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Viroporins, integral viral membrane ion channel proteins, interact with host-cell proteins deregulating physiological processes and activating inflammasomes. Severity of COVID-19 might be associated with hyperinflammation, thus we aimed at the complete immunoinformatic analysis of the SARS-CoV-2 viroporin E, P0DTC4. We also identified the human proteins interacting with P0DTC4 and the enriched molecular functions of the corresponding genes. The complete sequence of P0DTC4 in FASTA format was processed in 10 databases relative to secondary and tertiary protein structure analyses and prediction of optimal vaccine epitopes. Three more databases were accessed for the retrieval and the molecular functional characterization of the P0DTC4 human interactors. The immunoinformatics analysis resulted in the identification of 4 discontinuous B-cell epitopes along with 1 linear B-cell epitope and 11 T-cell epitopes which were found to be antigenic, immunogenic, nonallergen, nontoxin, and unable to induce autoimmunity thus fulfilling prerequisites for vaccine design. The functional enrichment analysis showed that the predicted host interactors of P0DTC4 target the cellular acetylation network. Two of the identified host-cell proteins – BRD2 and BRD4 – have been shown to be promising targets for antiviral therapy. Thus, our findings have implications for COVID-19 therapy and indicate that viroporin E could serve as a promising vaccine target against SARS-CoV-2. Validation experiments are required to complement these in silico results.
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Affiliation(s)
- Erasmia Rouka
- Department of Respiratory Medicine, Faculty of Medicine, School of Health Sciences, University of Thessaly, BIOPOLIS, Larissa, Greece.,Department of Physiology, Faculty of Medicine, School of Health Sciences, University of Thessaly, BIOPOLIS, Larissa, Greece
| | - Konstantinos I Gourgoulianis
- Department of Respiratory Medicine, Faculty of Medicine, School of Health Sciences, University of Thessaly, BIOPOLIS, Larissa, Greece
| | - Sotirios G Zarogiannis
- Department of Respiratory Medicine, Faculty of Medicine, School of Health Sciences, University of Thessaly, BIOPOLIS, Larissa, Greece.,Department of Physiology, Faculty of Medicine, School of Health Sciences, University of Thessaly, BIOPOLIS, Larissa, Greece
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Pham T, Perry JL, Dosey TL, Delcour AH, Hyser JM. The Rotavirus NSP4 Viroporin Domain is a Calcium-conducting Ion Channel. Sci Rep 2017; 7:43487. [PMID: 28256607 PMCID: PMC5335360 DOI: 10.1038/srep43487] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Accepted: 01/24/2017] [Indexed: 12/15/2022] Open
Abstract
Viroporins are small virus-encoded ion channel proteins. Most viroporins are monovalent selective cation channels, with few showing the ability to conduct divalent cations, like calcium (Ca2+). Nevertheless, some viroporins are known to disrupt host cell Ca2+ homeostasis, which is critical for virus replication and pathogenesis. Rotavirus nonstructural protein 4 (NSP4) is an endoplasmic reticulum transmembrane glycoprotein that has a viroporin domain (VPD), and NSP4 viroporin activity elevates cytosolic Ca2+ in mammalian cells. The goal of this study was to demonstrate that the NSP4 VPD forms an ion channel and determine whether the channel can conduct Ca2+. Using planar lipid bilayer and liposome patch clamp electrophysiology, we show that a synthetic peptide of the NSP4 VPD has ion channel activity. The NSP4 VPD was selective for cations over anions and channel activity was observed to have both well-defined "square top" openings as well as fast current fluctuations, similar to other viroporins. Importantly, the NSP4 VPD showed similar conductance of divalent cations (Ca2+ and Ba2+) as monovalent cations (K+), but a viroporin defective mutant lacked Ca2+ conductivity. These data demonstrate that the NSP4 VPD is a Ca2+-conducting viroporin and establish the mechanism by which NSP4 disturbs host cell Ca2+ homeostasis.
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Affiliation(s)
- Thieng Pham
- Department of Biology and Biochemistry, University of Houston, Houston, TX, USA
| | - Jacob L. Perry
- Alkek Center for Metagenomic and Microbiome Research, Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, USA
| | - Timothy L. Dosey
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Anne H. Delcour
- Department of Biology and Biochemistry, University of Houston, Houston, TX, USA
| | - Joseph M. Hyser
- Alkek Center for Metagenomic and Microbiome Research, Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, USA
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Abstract
Eukaryotic cells have evolved a myriad of ion channels, transporters, and pumps to maintain and regulate transmembrane ion gradients. As intracellular parasites, viruses also have evolved ion channel proteins, called viroporins, which disrupt normal ionic homeostasis to promote viral replication and pathogenesis. The first viral ion channel (influenza M2 protein) was confirmed only 23 years ago, and since then studies on M2 and many other viroporins have shown they serve critical functions in virus entry, replication, morphogenesis, and immune evasion. As new candidate viroporins and viroporin-mediated functions are being discovered, we review the experimental criteria for viroporin identification and characterization to facilitate consistency within this field of research. Then we review recent studies on how the few Ca(2+)-conducting viroporins exploit host signaling pathways, including store-operated Ca(2+) entry, autophagy, and inflammasome activation. These viroporin-induced aberrant Ca(2+) signals cause pathophysiological changes resulting in diarrhea, vomiting, and proinflammatory diseases, making both the viroporin and host Ca(2+) signaling pathways potential therapeutic targets for antiviral drugs.
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Affiliation(s)
- Joseph M Hyser
- Alkek Center for Metagenomic and Microbiome Research.,Department of Molecular Virology and Microbiology, and
| | - Mary K Estes
- Department of Molecular Virology and Microbiology, and.,Department of Medicine, Baylor College of Medicine, Houston, Texas 77030-3411;
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