In vivo functional characterization of the SARS-Coronavirus 3a protein in Drosophila

• Published in: Biochemical and biophysical research communications Vol. 337; no. 2; pp. 720 - 729
• Main Authors: Wong, S.L. Alan, Chen, Yiwei, Chan, Chak Ming, Chan, C.S. Michael, Chan, Paul K.S., Chui, Y.L., Fung, Kwok Pui, Waye, Mary M.Y., Tsui, Stephen K.W., Chan, H.Y. Edwin
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 18.11.2005
• Subjects: Animals; Animals, Genetically Modified; Antibodies, Monoclonal - immunology; Clathrin - metabolism; Cytoplasm - metabolism; Drosophila; Drosophila - genetics; Endocytosis; Gene Transfer Techniques; Genetic screen; Humans; Phenotype; SARS coronavirus; SARS Virus - genetics; Transgenics; U274; Viral Proteins - genetics; Viral Proteins - metabolism; Transgenics; X1; Genetic screen; U274; Drosophila
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2005.09.098

The Severe Acute Respiratory Syndrome-Coronavirus (SARS-CoV) 3a locus encodes a 274 a.a. novel protein, and its expression has been confirmed in SARS patients. To study functional roles of 3a, we established a transgenic fly model for the SARS-CoV 3a gene. Misexpression of 3a in Drosophila caused a dominant rough eye phenotype. Using a specific monoclonal antibody, we demonstrated that the 3a protein displayed a punctate cytoplasmic localization in Drosophila as in SARS-CoV-infected cells. We provide genetic evidence to support that 3a is functionally related to clathrin-mediated endocytosis. We further found that 3a misexpression induces apoptosis, which could be modulated by cellular cytochrome c levels and caspase activity. From a forward genetic screen, 78 dominant 3a modifying loci were recovered and the identity of these modifiers revealed that the severity of the 3 a-induced rough eye phenotype depends on multiple cellular processes including gene transcriptional regulation.