An acidic activation-like domain of the Sendai virus P protein is required for RNA synthesis and encapsidation.
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.
Department of Genetics and Microbiology, University of Geneva School of Medicine, CMU, Switzerland.
J
J
Curran
T
T
Pelet
D
D
Kolakofsky
D012321:DNA-Directed RNA Polymerases / Q000737:chemistry / Q000378:metabolism*; D010222:Parainfluenza Virus 1, Human / Q000254:growth & development*; D010750:Phosphoproteins / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D012367:RNA, Viral / Q000096:biosynthesis; D014158:Transcription, Genetic; D014764:Viral Proteins / Q000737:chemistry* / Q000378:metabolism; D014779:Virus Replication
C055859:P protein, Sendai virus; D010750:Phosphoproteins; D012367:RNA, Viral; D014764:Viral Proteins; C064365:L protein, Sendai virus; D012321:DNA-Directed RNA Polymerases