Endocytosis of the receptor-binding domain of SARS-CoV spike protein together with virus receptor ACE2.
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.
National Key Laboratory of Medical Molecular Biology, School of Basic Medicine, Peking Union Medical College, Tsinghua University and Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, Beijing 100005, China.
Shunxin
S
Wang
Feng
F
Guo
Kangtai
K
Liu
Hongliang
H
Wang
Shuan
S
Rao
Peng
P
Yang
Chengyu
C
Jiang
D000085962:Angiotensin-Converting Enzyme 2; D000818:Animals; D002460:Cell Line; D002522:Chlorocebus aethiops; D004705:Endocytosis; D005434:Flow Cytometry; D006801:Humans; D007141:Immunoglobulin Fc Fragments / Q000235:genetics; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D007703:Peptidyl-Dipeptidase A / Q000378:metabolism*; D011485:Protein Binding; D011991:Receptors, Virus / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D045473:Severe acute respiratory syndrome-related coronavirus / Q000502:physiology*; D064370:Spike Glycoprotein, Coronavirus; D014759:Viral Envelope Proteins / Q000235:genetics / Q000378:metabolism*
D007141:Immunoglobulin Fc Fragments; D008562:Membrane Glycoproteins; D011991:Receptors, Virus; D011993:Recombinant Fusion Proteins; D064370:Spike Glycoprotein, Coronavirus; D014759:Viral Envelope Proteins; C578557:spike glycoprotein, SARS-CoV; C578553:spike protein, mouse hepatitis virus; D007703:Peptidyl-Dipeptidase A; C000705307:ACE2 protein, human; D000085962:Angiotensin-Converting Enzyme 2