Question

What is the Spike protein found in the SARS-CoV-2 virus?

Describe the structure of the S protein (quaternary, tertiary, secondary and primary protein layers). Also highlight key domains and features of the structure of the S-protein that are important for its function.

Answer 1

1 corona virus spike protein is a class 1 fusion protein , large type 1 transmembrane protein .the recombinent spike protein binds with ace2 protein and the virus enter in to host cell spike proteins assemble in to trimers on the virus surface to form distinctive crown like appearance or corona

2 the corona virus spike contains three segments ,a large ectodomain ,a singlepass transmembrane anchor and a short intracellular tail .the ectodomain cosists s1 and s2 s1 is receptor binding subunits s2 i s membrane fusion subunit

fusion protein has a characteristic alpha helical coiled coil structure ,has s1 and s2 region .s1 contains two subdomains 1) n terminal domain 2).c terminal domain .both are receptor binding domains

s2 domain contain 2 heptad repeats , and purative fusion peptide

heptad repeats comprise repetitive heptapeptide abcdefg with and d beinghydrophobic residues. it helps in the formation of coiled coil that participate in fusion process

s1 domain contains receptor binding domain and is responsible for recognition and binding to the host cell receptor

s2 responsible for fusion between viral envelop and host cell membrane as it contains purative fusion peptide and the heptad repeat hr1 and hr2 thus the spike protein has a major role in virus entry and pathogenesis

3 steps in membrane fusion

1. receptor binding ,ph reduction , dissociation of s1 from s2

2 fusion peptide intercalated to hostcell membrane

3 the part of s protein nearest to the virus membrane refolds on to hr1 core to form 6 helix bundle .this 6hb is the final postfusion configuration of s2 protein