Recombinant SARS-CoV-2 B.1.1.529 S1 His-tag Protein, CF

Recombinant SARS-CoV-2 B.1.1.529 Spike S1 Subunit His-tag (Catalog # 11070-CV) binds Recombinant Human ACE-2 His-tag (933-ZN) in a functional ELISA.

2 μg/lane of Recombinant SARS-CoV-2 B.1.1.529 Spike S1 Subunit His-tag Protein (Catalog # 11070-CV) was resolved with SDS-PAGE under reducing (R) and non-reducing (NR) conditions and visualized by Coomassie® Blue staining, showing bands at 104-116 kDa.

Recombinant SARS-CoV-2 B.1.1.529 Spike S1 His-tag (Catalog #11070-CV) was immobilized on a Biacore Sensor Chip CM5, and binding to recombinant human ACE-2 (933-ZN) was measured at a concentration range between 0.184 nM and 94.3 nM. The double-referenced sensorgram was fit to a 1:1 binding model to determine the binding kinetics and affinity, with an affinity constant of Kd=1.57 nM.

• Reactivity: V
• Applications: Bioactivity
• Format: Carrier-Free

Recombinant SARS-CoV-2 B.1.1.529 S1 His-tag Protein, CF Summary

• Additional Information: Omicron Variant
• Details of Functionality: Measured by its binding ability in a functional ELISA with Recombinant Human ACE-2 His-tag (Catalog # 933-ZN).
• Source: Human embryonic kidney cell, HEK293-derived sars-cov-2 Spike S1 Subunit protein
  

  SARS-CoV-2 B.1.1.529 Spike S1 (Val16-Pro681) (Ala67Val, His69del, Val70del, Thr95Ile, Gly142Asp, Val143del, Tyr144del, Tyr145del, Asn211del, Leu212Ile, ins214Glu-Pro-Glu, Gly339Asp, Ser371Leu, Ser373Pro, Ser375Phe, Lys417Asn, Asn440Lys, Gly446Ser, Ser477Asn, Thr478Lys, Glu484Ala, Gln493Arg, Gly496Ser, Gln498Arg, Asn501Tyr, Tyr505His, Thr547Lys, Asp614Gly, His655Tyr, Asn679Lys, Pro681His) Accession # YP_009724390.1	6-His tag
  N-terminus	C-terminus

• Accession #: YP_009724390.1
• N-terminal Sequence: Val16
• Protein/Peptide Type: Recombinant Proteins
• Purity: >95%, by SDS-PAGE visualized with Silver Staining and quantitative densitometry by Coomassie® Blue Staining.
• Endotoxin Note: <0.10 EU per 1 μg of the protein by the LAL method.

Applications/Dilutions

• Dilutions:
  • Bioactivity
• Theoretical MW: 75 kDa.
  Disclaimer note: The observed molecular weight of the protein may vary from the listed predicted molecular weight due to post translational modifications, post translation cleavages, relative charges, and other experimental factors.
• SDS-PAGE: 104-116 kDa, under reducing conditions

Packaging, Storage & Formulations

• Storage: Use a manual defrost freezer and avoid repeated freeze-thaw cycles.
  • 12 months from date of receipt, -20 to -70 °C as supplied.
  • 1 month, 2 to 8 °C under sterile conditions after reconstitution.
  • 3 months, -20 to -70 °C under sterile conditions after reconstitution.
• Buffer: Lyophilized from a 0.2 μm filtered solution in PBS with Trehalose.
• Purity: >95%, by SDS-PAGE visualized with Silver Staining and quantitative densitometry by Coomassie® Blue Staining.
• Reconstitution Instructions: Reconstitute at 500 μg/mL in PBS.

Notes

This product is produced by and ships from R&D Systems, Inc., a Bio-Techne brand.

Alternate Names for Recombinant SARS-CoV-2 B.1.1.529 S1 His-tag Protein, CF

• SARS-CoV-2
• Spike S1 Subunit

Background

SARS-CoV-2, which causes the global pandemic coronavirus disease 2019 (Covid-19), belongs to a family of viruses known as coronaviruses that are commonly comprised of four structural proteins: Spike protein(S), Envelope protein (E), Membrane protein (M), and Nucleocapsid protein (N) (1). SARS-CoV-2 Spike Protein (S Protein) is a glycoprotein that mediates membrane fusion and viral entry. The S protein is homotrimeric, with each ~180-kDa monomer consisting of two subunits, S1 and S2 (2). In SARS-CoV-2, as with most coronaviruses, proteolytic cleavage of the S protein into two distinct peptides, S1 and S2 subunits, is required for activation. The S1 subunit is focused on attachment of the protein to the host receptor, while the S2 subunit is involved with cell fusion (3-5). A metallopeptidase, angiotensin‑converting enzyme 2 (ACE-2), has been identified as a functional receptor for SARS-CoV-2 through interaction with a receptor binding domain (RBD) located at the C-terminus of S1 subunit (6,7). The S1 subunit of SARS-CoV-2 shares 65% amino acid (aa) sequence identity with the S1 subunit of SARS-CoV-1, but only 22% aa sequence identity with the S1 subunit of MERS-CoV. The difference in aa sequence identity is consistent with the finding that SARS and MERS bind different cellular receptors (8). The S Protein of the SARS-CoV-2 virus binds ACE-2 with higher affinity and faster binding kinetics than its SARS-CoV-1 counterpart (9). Before binding to the ACE-2 receptor, structural analysis of the S1 trimer shows that only one of the three RBD domains in the trimeric structure is in the "up" conformation. This is an unstable and transient state that passes between trimeric subunits but is nevertheless an exposed state to be targeted for neutralizing antibody therapy (10). Polyclonal antibodies to the RBD of the SARS-CoV-2 S1 subunit have been shown to inhibit interaction with the ACE-2 receptor, confirming RBD as an attractive target for vaccinations or antiviral therapy (11). There is also promising work showing that the RBD may be used to detect presence of neutralizing antibodies present in a patient's bloodstream, consistent with developed immunity after exposure to the SARS-CoV-2 virus (12). Lastly, it has been demonstrated the S Protein can invade host cells through the CD147/EMMPRIN receptor and mediate membrane fusion (13). Several emerging SARS-CoV-2 genomes have been identified including the Omicron, or B.1.1.529, variant. First identified in November 2021 in South Africa, the Omicron variant quickly became the predominant SARS-CoV-2 variant and is considered a variant of concern (VOC). The Omicron variant contains 29 mutations in the S1 subunit of SARS-Cov-2, of which 15 are located in the RBD domain (14-16). The majority of the RBD mutations are involved in ACE-2 binding and they allow the Omicron variant to bind ACE-2 with greater affinity and, potentially, increased transmissibility (14-18). Additionally, several of these mutations have been identified in facilitating immune escape and reducing neutralization activity to several monoclonal antibodies (14-16). The Omicron variant also contains four mutations within the N terminal domain of the S1 subunit, which may enhance immune evasion (16). Several unique mutations are present in the S1 subunit which have unknown impacts on receptor binding or antibody neutralization. The study of the Omicron variant's impact on immune escape and reduced neutralization activity to monoclonal antibodies along with an increased risk of reinfection, even among vaccinated individuals, remains ongoing (19).

1. Wu, F. et al. (2020) Nature 579:265.
2. Tortorici, M.A. and D. Veesler (2019) Adv. Virus Res. 105:93.
3. Bosch, B.J. et al. (2003) J. Virol. 77:8801.
4. Belouzard, S. et al. (2009) Proc. Natl. Acad. Sci. 106:5871.
5. Millet, J.K. and G.R. Whittaker (2015) Virus Res. 202:120.
6. Li, W. et al. (2003) Nature 426:450.
7. Wong, S.K. et al. (2004) J. Biol. Chem. 279:3197.
8. Jiang, S. et al. (2020) Trends. Immunol. https://doi.org/10.1016/j.it.2020.03.007.
9. Ortega, J.T. et al. (2020) EXCLI J. 19:410.
10. Wrapp, D. et al. (2020) Science 367:1260.
11. Tai, W. et al. (2020) Cell. Mol. Immunol. https://doi.org/10.1016/j.it.2020.03.007.
12. Okba, N.M.A. et al. (2020) Emerg. Infect. Dis. https://doi.org/10.3201/eid2607.200841.
13. Wang, K. et al. (2020) bioRxiv https://www.biorxiv.org/content/10.1101/2020.03.14.988345v1.
14. Shah, M. and Woo, H.G. (2021) bioRxiv https://doi.org/10.1101/2021.12.04.471200.
15. Lupala, C.S. et al. (2021) bioRxiv https://doi.org/10.1101/2021.12.10.472102.
16. Sarkar, R. et al. (2021) medRxiv https://doi.org/10.1101/2021.12.04.21267284.
17. Zhang, L. et al. (2020) Nat Commun. 11:6013.
18. Lasek-Nesselquist, E. et al. (2021) medRxiv https://doi.org/10.1101/2021.03.10.21253285.
19. Callaway, E. and Ledford, H. (2021) Nature 600:197.

Bioinformatics

• Uniprot:
  • YP_009724390.1(Llama)