Mutations in the receptor-binding domain of human SARS CoV-2 spike protein increases its affinity to bind human ACE-2 receptor

The severe acute respiratory syndrome virus-2 (SARS CoV-2) infection has resulted in the current global pandemic. The binding of SARS CoV-2 spike protein receptor-binding domain (RBD) to the human angiotensin converting enzyme-2 (ACE-2) receptor causes the host infection. The spike protein has undergone several mutations with reference to the initial strain isolated during December 2019 from Wuhan, China. A number of these mutant strains have been reported as variants of concern and as variants being monitored. Some of these mutants are known to be responsible for increased transmissibility of the virus. The reason for the increased transmissibility caused by the point mutations can be understood by studying the structural implications and inter-molecular interactions in the binding of viral spike protein RBD and human ACE-2. Here, we use the crystal structure of the RBD in complex with ACE-2 available in the public domain and analyse the 250 ns molecular dynamics (MD) simulations of wild-type and mutants; K417N, K417T, N440K, N501Y, L452R, T478K, E484K and S494P. The ionic, hydrophobic and hydrogen bond interactions, amino acid residue flexibility, binding energies and structural variations are characterized. The MD simulations provide clues to the molecular mechanisms of ACE-2 receptor binding in wild-type and mutant complexes. The mutant spike proteins RBD were associated with greater binding affinity with ACE-2 receptor. Communicated by Ramaswamy H. Sarma.

SARS-CoV-2 Delta (B.1.617.2) Variant: A Unique T478K Mutation in Receptor Binding Motif (RBM) of Spike Gene

Over two hundred twenty-eight million cases of coronavirus disease 2019 (COVID-19) in the world have been reported until the 21st of September 2021 after the first rise in December 2019. The virus caused the disease called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Over 4 million deaths blame COVID-19 during the last one year and 8 months in the world. Currently, four SARS-CoV-2 variants of concern are mainly focused by pandemic studies with limited experiments to translate the infectivity and pathogenicity of each variant. The SARS-CoV-2 α, β, γ, and δ variant of concern was originated from United Kingdom, South Africa, Brazil/Japan, and India, respectively. The classification of SARS-CoV-2 variant is based on the mutation in spike (S) gene on the envelop of SARS-CoV-2. This review describes four SARS-CoV-2 α, β, γ, and δ variants of concern including SARS-CoV-2 ε, ζ, η, ι, κ, and B.1.617.3 variants of interest and alert. Recently, SARS-CoV-2 δ variant prevails over different countries that have 3 unique mutation sites: E156del/R158G in the N-terminal domain and T478K in a crucial receptor binding domain. A particular mutation in the functional domain of the S gene is probably associated with the infectivity and pathogenesis of the SARS-CoV-2 variant.

Preliminary report on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Spike mutation T478K

Several severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) variants have emerged, posing a renewed threat to coronavirus disease 2019 containment and to vaccine and drug efficacy. In this study, we analyzed more than 1,000,000 SARS‐CoV‐2 genomic sequences deposited up to April 27, 2021, on the GISAID public repository, and identified a novel T478K mutation located on the SARS‐CoV‐2 Spike protein. The mutation is structurally located in the region of interaction with human receptor ACE2 and was detected in 11,435 distinct cases. We show that T478K has appeared and risen in frequency since January 2021, predominantly in Mexico and the United States, but we could also detect it in several European countries.

We analyzed 1,180,571 SARS‐CoV‐2 samples from the public repository GISAID (updated to April 27, 2021).

We detected a mutation in SARS‐CoV‐2 Spike (S) protein amino acid 478, S:T478K, which has been growing in sequence in North America (especially Mexico) since January, 2021.

S:T478K is one of the characterizing mutations of lineage B.1.1.519, which is currently independent from B.1.1.7 and B.1.351.

S:T478K is affecting the Spike binding domain with human receptor ACE2, increasing the electrostatic potential on the interface.

Previous experiments show that S:T478K is a possible genetic route for SARS‐CoV‐2 to escape immune recognition.