Structure and Function of the Influenza Virus RNP
Debra Elton, Paul Digard, Laurence Tiley and Juan Ortin
from: Influenza Virology: Current Topics (Edited by: Yoshihiro Kawaoka). Caister Academic Press, U.K. (2006)
Influenza viruses have negative sense segmented RNA genomes, which are packaged into transcriptionally active ribonucleoproteins (RNPs). These RNPs are transcribed and replicated in the nucleus of host cells. During the replication cycle two types of positive sense RNA are synthesized; capped and polyadenylated messenger RNA and uncapped full length complementary (c)RNA. Complementary RNA acts as the replicative intermediate for synthesis of further negative sense genomic RNA. This cycle is carried out by the viral RNA-dependent RNA polymerase, a heterotrimeric complex which binds RNA through structure and sequence-specific interactions and has multiple functions including capped-RNA-binding activity, RNA endonuclease, polymerase and polyadenylation activities. These activities have specific roles during the viral transcription cycle and are controlled by interactions between the protein components and the RNA promoter structure. The mechanisms involved in the synthesis of viral messenger RNA are fairly well characterised, but less is known about the process of genome replication and the factors that control it. On the other hand, recent advances have been made towards elucidating the structure of the molecular machines responsible for virus RNA synthesis read more ...