Structure-Function Insights Into the RNA-Dependent RNA Polymerase of the dsRNA Bacteriophage Φ6
Minni R. L. Koivunen, L. Peter Sarin and Dennis H. Bamford
from: Segmented Double-stranded RNA Viruses: Structure and Molecular Biology (Edited by: John T. Patton). Caister Academic Press, U.K. (2008)
RNA-dependent RNA polymerases (RdRPs) are critical components in the life cycle of double-stranded RNA (dsRNA) viruses. However, it is not fully understood how these important enzymes function during viral replication. Expression and characterization of the purified recombinant RdRP of bacteriophage Φ6, a member of the Cystoviridae family, is the first direct demonstration of RdRP activity catalyzed by a single protein from a dsRNA virus. The recombinant Φ6 RdRP is highly active in vitro, possesses RNA replication and transcription activities, and is capable of using both homologous and heterologous RNA molecules as templates. The crystal structure of the Φ6 polymerase, solved in complex with a number of ligands, provides insights towards understanding the mechanism of primer-independent initiation of RNA-dependent RNA polymerization. Furthermore, the purified Φ6 RdRP displays processive elongation in vitro and self-assembles along with polymerase complex proteins into subviral particles that are fully functional in vitro and in vitro. This chapter will review what is currently known about the structure and function of the Φ6 RdRP with a special emphasis on the mechanism of primer-independent initiation of Φ6 viral RNA synthesis read more ...