Characterization of the 3a Protein of SARS-associated Coronavirus in Infected Vero E6 Cells and SARS Patients

Research Center for Proteome Analysis, Key Lab of Proteomics, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue-Yang Road, Shanghai 200031, China.
Journal of Molecular Biology (Impact Factor: 4.33). 08/2004; 341(1):271-9. DOI: 10.1016/j.jmb.2004.06.016
Source: PubMed


Proteomics was used to identify a protein encoded by ORF 3a in a SARS-associated coronavirus (SARS-CoV). Immuno-blotting revealed that interchain disulfide bonds might be formed between this protein and the spike protein. ELISA indicated that sera from SARS patients have significant positive reactions with synthesized peptides derived from the 3a protein. These results are concordant with that of a spike protein-derived peptide. A tendency exists for co-mutation between the 3a protein and the spike protein of SARS-CoV isolates, suggesting that the function of the 3a protein correlates with the spike protein. Taken together, the 3a protein might be tightly correlated to the spike protein in the SARS-CoV functions. The 3a protein may serve as a new clinical marker or drug target for SARS treatment.

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    • "The 3a protein contains three transmembrane domains at the N-terminus and a C-terminal cytoplasmic domain of ~150 amino acids [18]. The cytoplasmic domain contains a tyrosine based sorting motif, YXXΦ (where X can be any residue and Φ is a residue with a bulky hydrophobic side chain) and a di-acidic EXD motif. "
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    • "The pattern of a potential gene located between the S and E genes is conserved in all three groups of coronavirus genomes. Only the genomes of SARS-CoV, HCoV-NL63 and PEDV have one complete ORF in this locus, whereas the genes in five other coronaviruses are truncated with only short ORFs due to mutations [3]. The ORF3 gene of several coronaviruses, including transmissible gastroenteritis virus (TGEV), can be recognized with insertions and deletions suggesting this area of the genome may be involved in viral pathogenicity [4]. "
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    • "Further, characterization of the 3a protein of SARS-CoV in infected Vero E6 cells and sera from SARS patients showed that there was a tendency existed for co-mutation between the 3a protein and the spike protein of SARS-CoV isolates. The conclusion was that the 3a protein might be tightly correlated to the spike protein in the SARS-CoV functions and it may serve as a new clinical marker or drug target for SARS treatment (Zeng et al., 2004b). To analyze the differential cellular response to SARS-CoV, the proteome of Vero E6 cells with and without infection of SARS- CoV were resolved and quantitated with two-dimensional gel electrophoresis followed by ESI-MS/MS identification. "
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