title: Short self-interacting N-terminal region of rubella virus capsid protein is essential for cooperative actions of capsid and nonstructural p150 proteins.
abstract: Nucleocapsid formation is a primary function of the rubella virus capsid protein, which also promotes viral RNA synthesis via an unknown mechanism. The present study demonstrates that in infected cells, the capsid protein is associated with the nonstructural p150 protein via the short self-interacting N-terminal region of the capsid protein. Mutational analyses indicated that hydrophobic amino acids in this N-terminal region are essential for its N-terminal self-interaction, which is critical for the capsid-p150 association. An analysis based on a subgenomic replicon system demonstrated that the self-interacting N-terminal region of the capsid protein plays a key role in promoting viral gene expression. Analyses using a virus-like particle (VLP) system also showed that the self-interacting N-terminal region of the capsid protein is not essential for VLP production but is critical for VLP infectivity. These results demonstrate that the close cooperative actions of the capsid protein and p150 require the short self-interacting N-terminal region of the capsid protein during the life cycle of the rubella virus.
  
  
  OBJECTIVE
  The capsid protein of rubella virus promotes viral RNA replication via an unknown mechanism. This protein interacts with the nonstructural protein p150, but the importance of this interaction is unclear. In this study, we demonstrate that the short N-terminal region of the capsid protein forms a homo-oligomer that is critical for the capsid-p150 interaction. These interactions are required for the viral-gene-expression-promoting activity of the capsid protein, allowing efficient viral growth. These findings provide information about the mechanisms underlying the regulation of rubella virus RNA replication via the cooperative actions of the capsid protein and p150.
authors: Department of Virology 3, National Institute of Infectious Diseases, Tokyo, Japan.
authors: Masafumi
authors: M
authors: Sakata
authors: Department of Virology 3, National Institute of Infectious Diseases, Tokyo, Japan.
authors: Noriyuki
authors: N
authors: Otsuki
authors: Department of Virology 3, National Institute of Infectious Diseases, Tokyo, Japan.
authors: Kiyoko
authors: K
authors: Okamoto
authors: Department of Virology 3, National Institute of Infectious Diseases, Tokyo, Japan.
authors: Masaki
authors: M
authors: Anraku
authors: Department of Virology 3, National Institute of Infectious Diseases, Tokyo, Japan.
authors: Misato
authors: M
authors: Nagai
authors: Department of Virology 3, National Institute of Infectious Diseases, Tokyo, Japan.
authors: Makoto
authors: M
authors: Takeda
authors: Department of Virology 3, National Institute of Infectious Diseases, Tokyo, Japan yoshiom@nih.go.jp.
authors: Yoshio
authors: Y
authors: Mori
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002213:Capsid / Q000737:chemistry / Q000378:metabolism; D036022:Capsid Proteins / Q000235:genetics* / Q000378:metabolism; D002522:Chlorocebus aethiops; D015967:Gene Expression Regulation, Viral; D057809:HEK293 Cells; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008969:Molecular Sequence Data; D009154:Mutation; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D017434:Protein Structure, Tertiary; D012367:RNA, Viral / Q000235:genetics* / Q000378:metabolism; D012412:Rubella virus / Q000235:genetics* / Q000378:metabolism; D014709:Vero Cells; D017361:Viral Nonstructural Proteins / Q000235:genetics* / Q000378:metabolism; D014771:Virion / Q000235:genetics* / Q000378:metabolism; D014779:Virus Replication
chemical_list: D036022:Capsid Proteins; D012367:RNA, Viral; D017361:Viral Nonstructural Proteins