Volume 28, Issue 9 (12-2021)                   RJMS 2021, 28(9): 104-117 | Back to browse issues page

Research code: I-801
Ethics code: ندارد
Clinical trials code: ندارد

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Saedaei Jahromi B, Ahmadian G, Allahyari Fard N. Review of surface proteins of SARS-CoV-2 virus causing COVID-19. RJMS. 2021; 28 (9) :104-117
URL: http://rjms.iums.ac.ir/article-1-6845-en.html
National Institute of Genetic Engineering and Biotechnology (NIGEB), Systems Biotechnology Department, Tehran, Iran , allahyar@nigeb.ac.ir
Abstract:   (924 Views)
The COVID-19 pandemic is an urgent global health emergency and is an infectious disease caused by the SARS-CoV-2 virus. Severe Acute Respiratory Syndrome, which is the result of SARS-CoV-2 virus pathogenicity, has caused a worldwide pandemic and has affected all aspects of individual, social, and economic life. To date, millions of cases and thousands of deaths have been reported in more than 200 countries, and the outbreak continues.
Preventive measures, drug design, vaccine design, and preparation of programs to combat the disease, require accurate knowledge of the nature, parts, and function of the surface proteins of SARS-CoV-2. Therefore, in this article, the diversity, structure, and mechanisms related to SARS-CoV-2 surface proteins were reviewed and presented based on the latest scientific findings published in the Web of Science, PubMed, Scopus, ScienceDirect, Google Scholar databases in 2020 and 2021.
Results and Conclusion: Coronaviruses (CoV) mainly cause infections of the respiratory and gastrointestinal tracts and are genetically classified into four genera, Alphacoronavirus, Betacoronavirus, Gammacoronavirus, and Deltacoronavirus. human CoV can damage various tissues and activate apoptotic cascades. SARS-CoV, MERS-CoV, and some human CoV, including HCoV-OC43 and HCoV-HKU1, belong to the genus Betacoronavirus. SARS-CoV-2 particles have a spherical shape that their diameters are approximately 100 nm. Coronaviruses have the largest genome of all RNA viruses. SARS-CoV-2 has a positive single-stranded RNA of approximately 30 Kb. The first reading frame, which accounts for about 67% of the total genome, with approximately 20 Kb, encodes 16 nonstructural proteins (NSPs), and the remaining 10 Kb frames encode structural and peripheral proteins. SARS-CoV-2 has four surface proteins including surface glycoprotein called S protein, nucleocapsid protein (N), matrix protein (M), and coating protein named E. The S protein plays an important role in the first step of infections. The S protein has two domains, S1 and S2, and is most important in interacting with the receptor protein and the host entrance. The SARS-CoV-2 virus uses the Angiotensin-converting enzyme 2 (ACE2) as the major receptor and the CD209L protein as the lateral receptor to enter the host cell. RBD is the part of S1 that binds to the host receptor. Also, the RBM or receptor binding motif) has an important role in the binding. These proteins can be found in influenza viruses, human immunodeficiency virus (HIV), and Ebola virus. These proteins have 1273 amino acids and a molecular weight of 180-200 kDa. Furin protease binds S protein with high affinity and cleaves the S protein into S1 and S2 domains.  Spike proteins also have a polysaccharide coating that deprives the host immune system of the ability to identify itself as a foreign agent. The S protein is a trimmer protein that has two distinct structural modes, including pre-binding and post-binding. Pre-accession detection by the immune system, which is based on the glycosylated coating of the viral protein spike surface, is critical to eliciting an effective immune response. In the S domain, RBD, NTD, and CTD regions are known. One or both NTD and CTD domains have the potential to bind to the receptor and act as the RBD region. The N-terminal region binds to polysaccharide molecules. The role of the CTD region is to identify ACE2 and DPP4 receptors. The S2 domain consists of five domains that are responsible for fusion and entry into the host cell. These five domains include the FP, HR1, HR2, TM peptides, and the cytoplasmic region. The supplement peptide contains 15 to 20 protected amino acids. This amino acid is generally hydrophobic and glycine and alanine are among the many amino acids of this peptide. The nucleocapsid N protein is a structural protein. This protein binds to the RNA virus and is involved in processes related to the virus genome, such as genome replication and response to infectivity. This protein binds the RNA virus to the replicase-transcriptase (RTC) complex, which eventually encapsulates the genome after virions are prepared and help release virion particles. These proteins are highly phosphorylated, thereby increasing the strength of the protein to bind to RNA. M protein is another vital part of the virus that is involved in determining the structure of the virus coat. This protein can bind to all other structural proteins. M Protein, along with N protein, is involved in the assembly and release of virion particles. This protein is a dimer and can have two different structures. Since this protein is not similar in the human vital system and plays a role in the cell cycle of the virus, it can be a good target for drug design. In the SARS-CoV-2 construct, the smallest protein is protein E. In terms of number, these proteins are small in number, the coating proteins have ion channel activity and are membrane proteins. The main activity of this protein is in the assembly and release of the virus and it has no role in genome replication. By improving our understanding of the surface proteins of SARS-CoV-2, we may facilitate the development of appropriate antiviral drugs and vaccines to control and prevent diseases caused by known and potentially emerging Coronaviruses.
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Type of Study: review article | Subject: Biology

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