Cell entry of severe acute respiratory syndrome coronavirus (SARS-CoV) is mediated by the viral spike (S) protein. Amino acids 319–510 on the S protein have been mapped as the receptor-binding domain (RBD), which mediates binding to the SARS-CoV receptor angiotensin converting enzyme 2 (ACE2) on SARS-CoV susceptible cells. In this study, we expressed a fusion protein containing the human codon-optimized RBD of the SARS-CoV spike protein linked to the Fc portion of human IgG1 (named RBD-Fc) in HEK293 cells. The RBD-Fc protein was purified by affinity chromatography. The flow cytometry assay showed that the purified RBD-Fc protein could bind to ACE2. We demonstrated that the RBD spike protein alone could be internalized into SARS-CoV susceptible cells together with ACE2. We also showed that the removal of N-glycans from the RBD spike protein did not abolish this phenomenon. Our discoveries may have some implications for the development of the SARS vaccine.
【저자키워드】 RBD, receptor-binding domain, endocytosis, Receptor-binding domain (RBD), ACE2, angiotensin converting enzyme 2, SARS-CoV, severe acute respiratory syndrome coronavirus, Angiotensin converting enzyme 2 (ACE2), severe acute respiratory syndrome coronavirus (SARS-CoV), N-linked glycosylation, 【초록키워드】 ACE2, Vaccine, coronavirus, SARS-CoV, endocytosis, flow cytometry, Spike protein, Protein, cells, RBD, receptor, fusion protein, virus receptor, binding, N-glycan, acute respiratory syndrome, enzyme, SARS-CoV spike protein, viral spike, HEK293 cells, RBD-Fc, implication, susceptible, human IgG1, expressed, demonstrated, the RBD, the receptor-binding domain, the S protein, purified, susceptible cell, mapped,