Encapsidation of heterologous RNAs by bacteriophage MS2 coat protein.
AUTOR(ES)
Pickett, G G
RESUMO
The RNA bacteriophages of E. coli specifically encapsidate a single copy of the viral genome in a protein shell composed mainly of 180 molecules of coat protein. Coat protein is also a translational repressor and shuts off viral replicase synthesis by interaction with a RNA stem-loop containing the replicase initiation codon. We wondered whether the translational operator also serves as the viral pac site, the signal which mediates the exclusive encapsidation of viral RNA by its interaction with coat protein. To test this idea we measured the ability of lacZ RNA fused to the translational operator to be incorporated into virus-like particles formed from coat protein expressed from a plasmid. The results indicate that the operator-lacZ RNA is indeed encapsidated and that nucleotide substitutions in the translational operator which reduce the tightness of the coat protein-operator interaction also reduce or abolish encapsidation of the hybrid RNA. When coat protein is expressed in excess compared to the operator-lacZ RNA, host RNAs are packaged as well. However, elevation of the level of operator-lacZ RNA relative to coat protein results in its selective encapsidation at the expense of cellular RNAs. Our results are consistent with the proposition that this single protein-RNA interaction accounts both for translational repression and viral genome encapsidation.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=311200Documentos Relacionados
- The RNA binding site of bacteriophage MS2 coat protein.
- Control of translation of MS2 RNA cistrons by MS2 coat protein.
- Probing sequence-specific RNA recognition by the bacteriophage MS2 coat protein.
- Translational repression by bacteriophage MS2 coat protein does not require cysteine residues.
- Interactions of Escherichia coli RNA with bacteriophage MS2 coat protein: genomic SELEX