Recombinant protein of the receptor binding domain (RBD), Mutant (K417T-E484K-N501Y) of SARS-CoV-2 (COVID-19) Spike S1 from Wuhan pneumonia virus with N-terminal His-Tag and C-terminal GFP. The mutations K417T-E484K-N501Y are characteristic for the fast spreading SARS-CoV-2 virus Gamma variant (B.1.351 lineage) emerged in South Africa. These mutations are affecting the receptor binding domain (RBD) of the spike protein, which the virus uses to bind to human cells receptors and enter them. Due to the mutations, the virus is allowed to bind with higher affinity to human ACE2 receptor which results in approximately 160% increased transmissibility of the SARS-CoV-2 virus Gamma variant.
The spike (S) glycoprotein of coronaviruses is essential for binding of the virus to the host cell at the beginning of the infection process. The target protein is also a major immunogen and a possible target for entry inhibitors. The SARS-CoV-2 spike (S) protein is a large type I transmembrane protein composed of two subunits, S1 and S2. The S1 subunit contains a receptor-binding domain (RBD) responsible for binding to the host cell receptor angiotensin-converting enzyme 2 (ACE2). Several mutants of the spike protein are known. A new SARS-CoV-2 lineage called 20J/501Y.V3, also known as Gamma variant or P.1 lineage, exhibits several mutations. Compared to the previously circulating variants, the mutation E484K and K417T of SARS-CoV-2 Spike S1 (RBD) Gamma variant may affect neutralization by some polyclonal and monoclonal antibodies. Furthermore, the mutation N501Y may influence the binding affinity of the spike protein to hACE2. Therefore, the Gamma variant is considered as one of the most dangerous modification of the virus resulting in a 160% higher transmissibility.