Interference with bacteriophage phi 6 genomic RNA packaging by hairpin structures

X Qiao, J Qiao, L Mindich
1995 Journal of Virology  
Bacteriophage 6 has a genome of three segments of double-stranded RNA enclosed in a procapsid composed of four different proteins. The preformed procapsid is capable of packaging plus-strand transcripts of the genomic segments in an in vitro reaction. Minus-strand synthesis within the procapsid then results in the production of the double-stranded RNA genome. When plus-strand transcripts contain strong hairpin structures near the 3 ends, they are subject to heterologous recombination to remove
more » ... bination to remove the hairpins. We now find that the sequences bounded by the hairpins as well as those 3 to them are excluded from particles in packaging reactions. This finding implies that packaging occurs from the 5 end and that the explanation for the facilitation of recombination by the hairpin structures is the lack of entry of the 3 ends rather than a difficulty of progressing through the hairpin by the phage polymerase. Packaging of segment M is dependent on the packaging of segment S. An S segment containing a strong hairpin is able to facilitate the packaging of segment M. This result implies that there is more than one entry pore into the procapsid.
doi:10.1128/jvi.69.9.5502-5505.1995 fatcat:3rniyqg4onfgxfvews7jly5xai