Identification of two critical amino acid residues of the severe acute respiratory syndrome coronavirus spike protein for its variation in zoonotic tropism transition via a double substitution strategy.
Severe acute respiratory syndrome coronavirus (SARS-CoV) is a recently identified human coronavirus. The extremely high homology of the viral genomic sequences between the viruses isolated from human (huSARS-CoV) and those of palm civet origin (pcSARS-CoV) suggested possible palm civet-to-human transmission. Genetic analysis revealed that the spike (S) protein of pcSARS-CoV and huSARS-CoV was subjected to the strongest positive selection pressure during transmission, and there were six amino acid residues within the receptor-binding domain of the S protein being potentially important for SARS progression and tropism. Using the single-round infection assay, we found that a two-amino acid substitution (N479K/T487S) of a huSARS-CoV for those of pcSARS-CoV almost abolished its infection of human cells expressing the SARS-CoV receptor ACE2 but no effect upon the infection of mouse ACE2 cells. Although single substitution of these two residues had no effects on the infectivity of huSARS-CoV, these recombinant S proteins bound to human ACE2 with different levels of reduced affinity, and the two-amino acid-substituted S protein showed extremely low affinity. On the contrary, substitution of these two amino acid residues of pcSARS-CoV for those of huSRAS-CoV made pcSARS-CoV capable of infecting human ACE2-expressing cells. These results suggest that amino acid residues at position 479 and 487 of the S protein are important determinants for SARS-CoV tropism and animal-to-human transmission.
Qu
Xiu-Xia
XX
Department of Cell Biology and Genetics, College of Life Sciences, Peking University, Beijing, China.
Hao
Pei
P
Song
Xi-Jun
XJ
Jiang
Si-Ming
SM
Liu
Yan-Xia
YX
Wang
Pei-Gang
PG
Rao
Xi
X
Song
Huai-Dong
HD
Wang
Sheng-Yue
SY
Zuo
Yu
Y
Zheng
Ai-Hua
AH
Luo
Min
M
Wang
Hua-Lin
HL
Deng
Fei
F
Wang
Han-Zhong
HZ
Hu
Zhi-Hong
ZH
Ding
Ming-Xiao
MX
Zhao
Guo-Ping
GP
Deng
Hong-Kui
HK
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000085962:Angiotensin-Converting Enzyme 2; D001665:Binding Sites; D002268:Carboxypeptidases / Q000378:metabolism; D006801:Humans; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000502:physiology; D008969:Molecular Sequence Data; D007703:Peptidyl-Dipeptidase A; D045473:Severe acute respiratory syndrome-related coronavirus / Q000737:chemistry* / Q000472:pathogenicity; D045169:Severe Acute Respiratory Syndrome / Q000635:transmission*; D064370:Spike Glycoprotein, Coronavirus; D013329:Structure-Activity Relationship; D018523:Tropism; D014759:Viral Envelope Proteins / Q000737:chemistry* / Q000502:physiology; D015047:Zoonoses
D008562:Membrane Glycoproteins; D064370:Spike Glycoprotein, Coronavirus; D014759:Viral Envelope Proteins; C578557:spike glycoprotein, SARS-CoV; C578553:spike protein, mouse hepatitis virus; D002268:Carboxypeptidases; D007703:Peptidyl-Dipeptidase A; C000705307:ACE2 protein, human; C000705328:Ace2 protein, mouse; D000085962:Angiotensin-Converting Enzyme 2