The virion N protein of infectious bronchitis virus is more phosphorylated than the N protein from infected cell lysates.
Because phosphorylation of the infectious bronchitis virus (IBV) nucleocapsid protein (N) may regulate its multiple roles in viral replication, the dynamics of N phosphorylation were examined. 32P-orthophosphate labeling and Western blot analyses confirmed that N was the only viral protein that was phosphorylated. Pulse labeling with 32P-orthophosphate indicated that the IBV N protein was phosphorylated in the virion, as well as at all times during infection in either chicken embryo kidney cells or Vero cells. Pulse-chase analyses followed by immunoprecipitation of IBV N proteins using rabbit anti-IBV N polyclonal antibody demonstrated that the phosphate on the N protein was stable for at least 1 h. Simultaneous labeling with 32P-orthophosphate and 3H-leucine identified a 3.5-fold increase in the 32P:3H counts per minute (cpm) ratio of N in the virion as compared to the 32P:3H cpm ratio of N in the cell lysates from chicken embryo kidney cells, whereas in Vero cells the 32P:3H cpm ratio of N from the virion was 10.5-fold greater than the 32P:3H cpm ratio of N from the cell lysates. These studies are consistent with the phosphorylation of the IBV N playing a role in assembly or maturation of the viral particle.
Jayaram
Jyothi
J
Department of Veterinary Pathobiology, Texas A&M University, College Station, TX 77843-4467, USA.
Youn
Soonjeon
S
Collisson
Ellen W
EW
D000818:Animals; D002460:Cell Line; D002642:Chick Embryo; D002522:Chlorocebus aethiops; D000086462:Coronavirus Nucleocapsid Proteins; D001351:Infectious bronchitis virus / Q000378:metabolism / Q000502:physiology*; D019590:Nucleocapsid Proteins / Q000378:metabolism*; D010766:Phosphorylation; D014709:Vero Cells; D014779:Virus Replication
D000086462:Coronavirus Nucleocapsid Proteins; D019590:Nucleocapsid Proteins