SARS-CoV-2 accessory protein 7b forms homotetramers in detergent
A global pandemic is underway caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The SARS-CoV-2 genome, like its predecessor SARS-CoV, contains open reading frames that encode accessory proteins involved in virus-host interactions active during infection and which likely con...
| Main Authors: | , , , , |
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| Format: | Journal Article |
| Language: | English |
| Published: |
2023
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| Online Access: | https://hdl.handle.net/10356/164537 |
| _version_ | 1824456370646155264 |
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| author | Surya, Wahyu Queralt-Martin, Maria Mu, Yuguang Aguilella, Vicente M. Torres, Jaume |
| author2 | School of Biological Sciences |
| author_facet | School of Biological Sciences Surya, Wahyu Queralt-Martin, Maria Mu, Yuguang Aguilella, Vicente M. Torres, Jaume |
| author_sort | Surya, Wahyu |
| collection | NTU |
| description | A global pandemic is underway caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The SARS-CoV-2 genome, like its predecessor SARS-CoV, contains open reading frames that encode accessory proteins involved in virus-host interactions active during infection and which likely contribute to pathogenesis. One of these accessory proteins is 7b, with only 44 (SARS-CoV) and 43 (SARS-CoV-2) residues. It has one predicted transmembrane domain fully conserved, which suggests a functional role, whereas most variability is contained in the predicted cytoplasmic C-terminus. In SARS-CoV, 7b protein is expressed in infected cells, and the transmembrane domain was necessary and sufficient for Golgi localization. Also, anti-p7b antibodies have been found in the sera of SARS-CoV convalescent patients. In the present study, we have investigated the hypothesis that SARS-2 7b protein forms oligomers with ion channel activity. We show that in both SARS viruses 7b is almost completely α-helical and has a single transmembrane domain. In SDS, 7b forms various oligomers, from monomers to tetramers, but only monomers when exposed to reductants. Combination of SDS gel electrophoresis and analytical ultracentrifugation (AUC) in both equilibrium and velocity modes suggests a dimer-tetramer equilibrium, but a monomer-dimer-tetramer equilibrium in the presence of reductant. This data suggests that although disulfide-linked dimers may be present, they are not essential to form tetramers. Inclusion of pentamers or higher oligomers in the SARS-2 7b model were detrimental to fit quality. Preliminary models of this association was generated with AlphaFold2, and two alternative models were exposed to a molecular dynamics simulation in presence of a model lipid membrane. However, neither of the two models provided any evident pathway for ions. To confirm this, SARS-2 p7b was studied using Planar Bilayer Electrophysiology. Addition of p7b to model membranes produced occasional membrane permeabilization, but this was not consistent with bona fide ion channels made of a tetrameric assembly of α-helices. |
| first_indexed | 2025-02-19T03:53:02Z |
| format | Journal Article |
| id | ntu-10356/164537 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2025-02-19T03:53:02Z |
| publishDate | 2023 |
| record_format | dspace |
| spelling | ntu-10356/1645372023-02-28T17:13:37Z SARS-CoV-2 accessory protein 7b forms homotetramers in detergent Surya, Wahyu Queralt-Martin, Maria Mu, Yuguang Aguilella, Vicente M. Torres, Jaume School of Biological Sciences Science::Biological sciences Accessory Protein 7b COVID-19 A global pandemic is underway caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The SARS-CoV-2 genome, like its predecessor SARS-CoV, contains open reading frames that encode accessory proteins involved in virus-host interactions active during infection and which likely contribute to pathogenesis. One of these accessory proteins is 7b, with only 44 (SARS-CoV) and 43 (SARS-CoV-2) residues. It has one predicted transmembrane domain fully conserved, which suggests a functional role, whereas most variability is contained in the predicted cytoplasmic C-terminus. In SARS-CoV, 7b protein is expressed in infected cells, and the transmembrane domain was necessary and sufficient for Golgi localization. Also, anti-p7b antibodies have been found in the sera of SARS-CoV convalescent patients. In the present study, we have investigated the hypothesis that SARS-2 7b protein forms oligomers with ion channel activity. We show that in both SARS viruses 7b is almost completely α-helical and has a single transmembrane domain. In SDS, 7b forms various oligomers, from monomers to tetramers, but only monomers when exposed to reductants. Combination of SDS gel electrophoresis and analytical ultracentrifugation (AUC) in both equilibrium and velocity modes suggests a dimer-tetramer equilibrium, but a monomer-dimer-tetramer equilibrium in the presence of reductant. This data suggests that although disulfide-linked dimers may be present, they are not essential to form tetramers. Inclusion of pentamers or higher oligomers in the SARS-2 7b model were detrimental to fit quality. Preliminary models of this association was generated with AlphaFold2, and two alternative models were exposed to a molecular dynamics simulation in presence of a model lipid membrane. However, neither of the two models provided any evident pathway for ions. To confirm this, SARS-2 p7b was studied using Planar Bilayer Electrophysiology. Addition of p7b to model membranes produced occasional membrane permeabilization, but this was not consistent with bona fide ion channels made of a tetrameric assembly of α-helices. Ministry of Education (MOE) Published version This research is supported by the Ministry of Education, Singapore, under its Academic Research Fund Tier 1 (Project RG92/21) to J.T..). M.Q. and V.A. acknowledge support from the Government of Spain MCIN/AEI/ http://dx.doi. org/10.13039/501100011033 (project no. 2019-108434 GB-I00 AEI/FEDER, UE and IJC2018-035283-I/AEI) and Universitat Jaume I (project no. UJI-A2020-21). 2023-01-31T05:56:28Z 2023-01-31T05:56:28Z 2022 Journal Article Surya, W., Queralt-Martin, M., Mu, Y., Aguilella, V. M. & Torres, J. (2022). SARS-CoV-2 accessory protein 7b forms homotetramers in detergent. Virology Journal, 19(1). https://dx.doi.org/10.1186/s12985-022-01920-0 1743-422X https://hdl.handle.net/10356/164537 10.1186/s12985-022-01920-0 36414943 2-s2.0-85142335366 1 19 en RG92/21 Virology Journal © The Author(s) 2022. Open Access. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativeco mmons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. application/pdf |
| spellingShingle | Science::Biological sciences Accessory Protein 7b COVID-19 Surya, Wahyu Queralt-Martin, Maria Mu, Yuguang Aguilella, Vicente M. Torres, Jaume SARS-CoV-2 accessory protein 7b forms homotetramers in detergent |
| title | SARS-CoV-2 accessory protein 7b forms homotetramers in detergent |
| title_full | SARS-CoV-2 accessory protein 7b forms homotetramers in detergent |
| title_fullStr | SARS-CoV-2 accessory protein 7b forms homotetramers in detergent |
| title_full_unstemmed | SARS-CoV-2 accessory protein 7b forms homotetramers in detergent |
| title_short | SARS-CoV-2 accessory protein 7b forms homotetramers in detergent |
| title_sort | sars cov 2 accessory protein 7b forms homotetramers in detergent |
| topic | Science::Biological sciences Accessory Protein 7b COVID-19 |
| url | https://hdl.handle.net/10356/164537 |
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