Regulation of respiratory syncytial virus nucleoprotein oligomerization by phosphorylation.

The negative-sense RNA genome of respiratory syncytial virus (RSV) is encapsidated by the viral nucleoprotein N, forming a left-handed helical nucleocapsid which serves as template for the viral polymerase. Specific oligomerization of N along the viral genome necessitates a switch of conformation of N, from the neosynthesized monomeric and RNA-free N protein, named N(0), to N-RNA oligomers. Although the binding of the N-terminal part of RSV phosphoprotein P plays the role of chaperone to impair RNA binding to N, N(0)-P interaction alone is not sufficient to prevent N oligomerization. Here, we explored the potential role of post translational modifications that could participate in the stability of N(0). Among the post translational modifications specifically identified on recombinant monomeric N, we validated the presence of a phosphorylation site on residue Y88 of N which modulates N oligomerization. Our results suggest that RSV N oligomerization depends on the regulation by post translational modifications.