Association of Rabies Virus Nominal Phosphoprotein (P) with Viral Nucleocapsid (NC) Is Enhanced by Phosphorylation of the Viral Nucleoprotein (N)

• Published in: Microbiology and immunology 2004-01, Vol.48 (5), p.399-409
• Main Authors: Toriumi, Harufusa, Kawai, Akihiko
• Format: Article
• Language: English
• Subjects: Antibodies, Monoclonal; Binding Sites; conformational changes; Immunoprecipitation; nucleocapsid; Nucleocapsid Proteins - chemistry; Nucleocapsid Proteins - metabolism; nucleoprotein; P-NC binding; phosphoprotein; Phosphorylation; Protein Binding; Protein Conformation; Rabies virus; Rabies virus - physiology; Transfection; Viral Proteins - chemistry; Viral Proteins - metabolism; Virus Assembly; Virus Replication
• ISSN: 0385-5600; 1348-0421
• DOI: 10.1111/j.1348-0421.2004.tb03529.x

We investigated possible role(s) of N protein phosphorylation in the rabies virus replication process. A large amount of P proteins are associated with the viral nucleocapsid (NC) in the infected cell, the amount which was greatly decreased by phosphatase‐treatment of the isolated NC, indicating that the phosphate group of N and/or P proteins is essential for their stable association with the NC. Immunoprecipitation studies were performed on the coexpressed normal N or phosphorylation deficient N(S389A) and P proteins, demonstrating that the P protein associated with phosphorylation‐deficient NC‐like structures was much less in amount than that associated with the wild type NC. Similar results were also obtained with a mutant P protein, PΔN19, which lacked the N‐terminal 19 amino acids and was capable of binding to the NC‐like structures but incapable of forming the RNA‐free N‐P complexes. Immunoprecipitation studies with mAb #402‐13 further suggested that the NC‐specific linear 402–13 epitope was exposed even on the P proteins which were associated with the phosphorylation‐deficient NC‐like structures, but such association was very weak as demonstrated by greatly decreased amounts of coprecipitated NC‐like structures. From these results, we assume that the phosphorylation of N protein enhances the association between the 402–13 epitope‐positive P protein and the NC probably by stabilizing such P‐NC binding.