Identification of the Membrane-Active Regions of the Severe Acute Respiratory Syndrome Coronavirus Spike Membrane Glycoprotein Using a 16/18-Mer Peptide Scan: Implications for the Viral Fusion Mechanism

Abstract

We have identified the membrane-active regions of the severe acute respiratory syndrome coronavirus (SARS CoV) spike glycoprotein by determining the effect on model membrane integrity of a 16/18-mer SARS CoV spike glycoprotein peptide library. By monitoring the effect of this peptide library on membrane leakage in model membranes, we have identified three regions on the SARS CoV spike glycoprotein with membrane-interacting capabilities: region 1, located immediately upstream of heptad repeat 1 (HR1) and suggested to be the fusion peptide; region 2, located between HR1 and HR2, which would be analogous to the loop domain of human immunodeficiency virus type 1; and region 3, which would correspond to the pretransmembrane region. The identification of these membrane-active regions, which are capable of modifying the biophysical properties of phospholipid membranes, supports their direct role in SARS CoV-mediated membrane fusion, as well as facilitating the future development of SARS CoV entry inhibitors.

Design, synthesis and screening of antisense peptide based combinatorial peptide libraries towards an aromatic region of SARS‐CoV

“…The aromatic-amino acid-rich region is highly conserved and is predominantly random coil either in phosphate buffer or in membranes (Sainz et al, 2005). Research has identified this region as a membrane-active region and possibly involved in the membrane fusion similar to the HIV gp41 Trp-rich domain (Guillen et al, 2005). It is also proposed that this region aligns with the fusion peptide to create an extended hydrophobic stretch that aids the lipid flow and the establishment of fusion pore (Sainz et al, 2005;Broer et al, 2006).…”

The Molecular Biology of Coronaviruses

“…Mutations in the MHV S protein HR1 and HR2 regions were shown to inhibit or abolish fusion (Luo and Weiss, 1998;Luo et al, 1999). Unlike its counterparts, however, the coronavirus S protein does not require cleavage to be fusogenic, and it contains an internal fusion peptide, although the exact assignment of this domain is not agreed upon (Guillen et al, 2005;Sainz et al, 2005). Even for MHV S and other cleaved S proteins, the fusion peptide is not the amino terminus of S2 created by cleavage (Luo and Weiss, 1998), as is the case in other type I fusion proteins.…”

A review of vaccine research and development: Human acute respiratory infections

“…In some CoV species, the S protein is cleaved by a protease to yield two noncovalently associated subunits, S1 and S2: S1 contains the receptor-binding site while S2 forms the membrane-anchored stalk region and mediates the fusion between the viral and cellular membranes, as observed with influenzavirus HA, paramyxovirus F or HIV Env glycoproteins. Available data suggest, however, that the SARS-CoV spike glycoprotein S is not cleaved into two moieties, but contains the viral receptor-binding site and neutralization epitopes in its N-terminal half and a fusion domain and two heptad repeats, as well as another neutralization epitope in its C-terminal half [89][90][91][92].…”