RECONSTITUTION OF ACTIVE REPLICASE IN PROCAPSIDS OF THE SEGMENTED DSRNA BACTERIOPHAGE-PHI-6

Bacteriophage Phi 6 has a genome of three segments of double-stranded RNA enclosed in a procapsid composed of four different proteins. The p reformed procapsid is capable of packaging plus strand transcripts of the genomic segments in an in vitro reaction. The plus strands then se rve as templates for in vitro minus strand synthesis. Procapsids that are missing protein P2 are incapable of minus strand synthesis. In thi s report we show that incubation with a cell extract containing P2 res ults in particles with normal amounts of attached P2 and with packagin g and replicase activity. Particles lacking P7 have reduced replicase activity which can be augmented by incubation with extracts containing P7, but the amount of attached P7 is small. (C) 1994 Academic Press, Inc.