Interaction of a peptide corresponding to the loop domain of the S2 SARS-CoV virus protein with model membranes

The severe acute respiratory syndrome coronavirus (SARS-CoV) envelope spike (S) glycoprotein is responsible for the fusion between the membranes of the virus and the target cell. In the case of the S2 domain of protein S, it has been found a highly hydrophobic and interfacial domain flanked by the heptad repeat 1 and 2 regions; significantly, different peptides pertaining to this domain have shown a significant leakage effect and an important plaque formation inhibition, which, similarly to HIV-1 gp41, support the role of this region in the fusion process. Therefore, we have carried out a study of the binding and interaction with model membranes of a peptide corresponding to segment 1073–1095 of the SARS-CoV S glycoprotein, peptide SARS_L in the presence of different membrane model systems, as well as the structural changes taking place in both the lipid and the peptide induced by the binding of the peptide to the membrane. Our results show that SARS_L strongly partitions into phospholipid membranes and organizes differently in lipid environments, displaying membrane activity modulated by the lipid composition of the membrane. These data would support its role in SARS-CoV mediated membrane fusion and suggest that the region where this peptide resides could be involved in the merging of the viral and target cell membranes.