Expression and Characterization of Recombinant S2 Subunit of SARS-coronavirus S Fusion Protein

摘要

The SARS-CoV Spike fusion protein subunit S2 plays an important role in viral entry by initiating fusion of the viral and cellular membranes. S2 exists in at least three different conformations within the trimeric glycoprotein complex. In the postfusion conformation (six-helix bundle, 6HB), the three helical heptad repeats of the HRC region pack in an antiparallel fashion into the hydrophobic grooves on the surface of the trimeric coiled-coil formed by the heptad repeat N-terminal (HRN) region. The HRN and HRC regions are separated by a 149 amino acid interhelical domain (IHD), which is thought to provide the flexibility required for the conformational change that occurs during the membrane fusion process. There is no structural information currently available for the interhelical domain and S2 in the prefusion state and fusion intermediate states.