Bovine coronavirus nonstructural protein ns2 is a phosphoprotein. |
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Authors: | G J Cox M D Parker L A Babiuk |
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Affiliation: | Department of Veterinary Microbiology, University of Saskatchewan, Saskatoon, Canada. |
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Abstract: | To investigate the nature of the bovine coronavirus (BCV) ns2 protein, the gene encoding this protein was cloned and was expressed as a beta-galactosidase fusion protein. Antiserum raised against this protein reacted specifically with BCV-infected fixed cells in indirect immunofluorescence microscopy and precipitated an in vitro synthesized product approximately 32-kDa in molecular weight and an equivalent protein from BCV-infected cells. The synthesis of ns2 was found to be similar to the structural proteins of BCV and pulse-chase experiments indicated that ns2 protein was stable and that it accumulated in BCV-infected cells. Synthesis of ns2 in the presence of [32P] orthophosphate revealed that it is a phosphoprotein. Phosphoamino acid analysis confirmed the phosphorylated nature of ns2 and identified serine and threonine as its phosphorylated amino acid residues. This is the first demonstration of a phosphorylated nonstructural protein in coronavirus-infected cells. |
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