Open AccessPhosphorylation of the Porcine Reproductive and Respiratory Syndrome Virus Nucleocapsid Protein
Author(s) -
Sarah K. Wootton,
Raymond R. R. Rowland,
Dongwan Yoo
Publication year - 2002
Publication title -
journal of virology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.617
H-Index - 292
eISSN - 1070-6321
pISSN - 0022-538X
DOI - 10.1128/jvi.76.20.10569-10576.2002
Subject(s) - biology , phosphoprotein , phosphorylation , microbiology and biotechnology , virus , protein phosphorylation , protein a/g , nucleolus , mononegavirales , serine , protein kinase a , recombinant dna , cytoplasm , fusion protein , biochemistry , paramyxoviridae , virology , gene , viral disease
Porcine reproductive and respiratory syndrome virus (PRRSV) is a cytoplasmic RNA virus with the unique or unusual feature of having a nucleocapsid (N) protein that is specifically transported to the nucleolus of virus-infected cells. In this communication, we show that the N protein is a phosphoprotein. Phosphoamino acid analysis of authentic and recombinant N proteins demonstrated that serine residues were exclusively phosphorylated. The pattern of phosphorylated N protein cellular distribution in comparison with that of [(35)S]methionine-labeled N protein suggested that phosphorylation does not influence subcellular localization of the protein. Time course studies showed that phosphorylation occurred during, or shortly after, synthesis of the N protein and that the protein remained stably phosphorylated throughout the life cycle of the virus to the extent that phosphorylated N protein was found in the mature virion. Two-dimensional electrophoresis and acid-urea gel electrophoresis showed that one species of the N protein is predominant in virus-infected cells, suggesting that multiple phosphorylated isoforms of N do not exist.