Genetic, Structural, Physicochemical, and Molecular Epidemiological Landscape of Three New Mutations Found in the Spike (S) Protein of Highly Transmissible Sri Lankan Delta Variant Sub-lineage AY.28: A222V, A701S, and A1078S

Figure 4

The zoomed structural views of Ala-701 (in pink) which is found prior to the commencement of a short betasheet ESN (structure shown is PDB ID: 6XCN). Alanine is predominantly found in beta strands but serine is primarily available in alpha helices [8]; consequently, the mutation A701S will destabilize the incumbent three residue beta strand and donate an extra residue for the structurally disordered loop. This mutation can collapse the beta strand into a longer coil structure and give flexibility to the S1/S2 protease susceptible region. This is further emphasized in the secondary structural prediction (Figure 5) where the tripeptide ENS is missing as a beta strand showing the instability of the region.