An acidic activation-like domain of the Sendai virus P protein is required for RNA synthesis and encapsidation

Virology. 1994 Aug 1;202(2):875-84. doi: 10.1006/viro.1994.1409.

Abstract

The Sendai virus polymerase is composed of the P and L proteins and carries out both mRNA synthesis and genome replication from the same nucleocapsid template. For mRNA synthesis, P interacts with the assembled NP of the nucleocapsid, and for genome replication, P interacts as well with unassembled NP for nascent chain assembly. The V and W nonstructural proteins, which are translated from edited P gene mRNAs and contain only the N-terminal half of the P protein, were found to inhibit genome replication but not mRNA synthesis. As genome replication is thought of as RNA synthesis plus concurrent encapsidation of the nascent chain, this half of P presumably plays a specific role in RNA encapsidation. Deletion analysis of the P gene found that residues 1-77 in the N-terminal half were in fact essential for RNA encapsidation. Moreover, either residues 1-77 or 78-144 also provided a function that was essential for RNA synthesis per se. Unlike other regions of P, such as those which bind NP in the C-terminal half, the N-terminal domains are very poorly conserved even among related viruses, show signs of acting in a position-independent manner, and, at least for RNA synthesis, are functionally redundant, similar to acidic activation domains of cellular transcription factors.

MeSH terms

  • DNA-Directed RNA Polymerases / chemistry
  • DNA-Directed RNA Polymerases / metabolism*
  • Parainfluenza Virus 1, Human / growth & development*
  • Phosphoproteins / chemistry*
  • Phosphoproteins / metabolism
  • Protein Binding
  • RNA, Viral / biosynthesis
  • Transcription, Genetic
  • Viral Proteins / chemistry*
  • Viral Proteins / metabolism
  • Virus Replication*

Substances

  • P protein, Sendai virus
  • Phosphoproteins
  • RNA, Viral
  • Viral Proteins
  • L protein, Sendai virus
  • DNA-Directed RNA Polymerases