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.
Curran
J
J
Department of Genetics and Microbiology, University of Geneva School of Medicine, CMU, Switzerland.
Pelet
T
T
Kolakofsky
D
D
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