Amino acids 1 to 422 of the spike protein of SARS associated coronavirus are required for induction of cyclooxygenase-2.
The causative agent of severe acute respiratory syndrome (SARS) has been identified as SARS-associated coronavirus (SARS-CoV). To evaluate the molecular mechanisms involved in the viral infection, in this study, we investigated the role of SARS-CoV Spike (S) protein in the regulation of cyclooxygenase-2 (COX-2). Expression of COX-2 stimulated by the S protein was verified by RT-PCR and western blot assay. To explore the relationship between S and COX-2, we constructed a series of plasmids containing truncated N-terminal fragments of the SARS-CoV S gene (designated from Sa to Si), which encoded truncated S proteins, and investigated whether these truncated proteins could induce effective expression of COX-2 in 293T cells. Our results showed that S(d) that encoded a truncated S protein with 422 amino acid residues (from 1 to 422 aa), a part of 672 amino-acid S1 subunit is crucial for the induction of COX-2 expression. Immunofluorescence examinations also give the evidence that these N terminal 422 amino acids of the S protein were also required for the correct localization of the protein. We also compared S protein sequences of SARS-CoV isolated during the SARS break with that from palm civets, a possible source of SARS-CoV found in humans. S protein residues (344, 360), which mutated in the epitome from palm civet to human being were characterized in 3D modeling of 252-375 amino acid fragment. Collectively, these results indicate that S protein of SARS-CoV induces the expression of COX-2 and an N-terminal fragment of the Spike protein is crucial for the induction. Our finding may provide clue for the induction of inflammation by SARS-CoV and cast insight into the severity of the SARS epidemic.
Liu
Mo
M
State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, P. R. China.
Gu
Chunfang
C
Wu
Jianguo
J
Zhu
Ying
Y
D000596:Amino Acids / Q000737:chemistry / Q000235:genetics; D000914:Antibodies, Viral; D002460:Cell Line; D051546:Cyclooxygenase 2 / Q000096:biosynthesis* / Q000235:genetics; D004790:Enzyme Induction / Q000187:drug effects*; D006801:Humans; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism* / Q000494:pharmacology; D045473:Severe acute respiratory syndrome-related coronavirus / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D064370:Spike Glycoprotein, Coronavirus; D014759:Viral Envelope Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000494:pharmacology*
D000596:Amino Acids; D000914:Antibodies, Viral; D008562:Membrane Glycoproteins; D064370:Spike Glycoprotein, Coronavirus; D014759:Viral Envelope Proteins; C578557:spike glycoprotein, SARS-CoV; C578553:spike protein, mouse hepatitis virus; D051546:Cyclooxygenase 2