Kinetic, quantitative, and functional analysis of multiple forms of the vesicular stomatitis virus nucleocapsid protein in infected cells.
Multiple forms of the vesicular stomatitis virus nucleocapsid protein N have been detected in infected cells. One form is complexed with the viral NS protein in a 1:1 molar ratio, and the other forms are distinguished by their more rapid sedimentation rates on glycerol gradients. I performed a series of experiments designed to analyze the relationships between these forms of the N protein. Pulse-chase experiments demonstrate that the N protein is made first as the form which binds to the NS protein, forming a 1-to-1 molar complex, and that with increasing times of chase it is either assembled into nucleocapsids or converted to the two higher sedimenting forms. Using a newly developed quantitative immunoblotting procedure, I have quantitated the three differentially sedimenting species of the N protein and have shown that at later times postinfection (6 to 7 h), the faster-sedimenting forms of the N protein account for as much as 50% of the soluble N protein in the cell. The activity of these forms has been assessed, with only the 1-to-1 molar N-NS complex demonstrating the ability to support the replication and encapsidation of viral genomic RNA. A model for the conversion of the N protein from the active N-NS complex into the other forms of the protein is presented, and the possible function of the N-protein self-complexes is discussed.
Peluso
R W
RW
Department of Microbiology, University of Minnesota, Minneapolis 55455.
D002213:Capsid / Q000502:physiology*; D007700:Kinetics; D008970:Molecular Weight; D011485:Protein Binding; D011498:Protein Precursors / Q000378:metabolism; D012367:RNA, Viral / Q000378:metabolism; D012995:Solubility; D014461:Ultracentrifugation; D014721:Vesicular stomatitis Indiana virus / Q000502:physiology* / Q000648:ultrastructure; D014758:Viral Core Proteins / Q000502:physiology*; D017361:Viral Nonstructural Proteins; D014779:Virus Replication
D011498:Protein Precursors; D012367:RNA, Viral; D014758:Viral Core Proteins; D017361:Viral Nonstructural Proteins