Regulated but not constitutive human respiratory syncytial virus (HRSV) P protein phosphorylation is essential for oligomerization

Purified human respiratory syncytial virus (HRSV) P phosphoprotein from transfected HEp-2 cells is able to oligomerize forming tetramers. The bulk of constitutive P protein phosphorylation (99. 8%) (serine residues 116, 117, 119, 232 and 237) can be removed without affecting protein oligomerization. However, dephosphorylated P protein, produced in bacteria, is unable to oligomerize. This difference can be explained by a transient P protein phosphorylation, detected in HEp-2 cells, that could be essential for P protein oligomerization.