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An electron microscope study of the proteins attached to polio virus RNA and its replicative form (RF)
Abstract:
A recently described method (Wu, M. and Davidson, N. (1978), Nucleic Acids Research 5, in press) for visualizing proteins attached to nucleic acids in the electron microscope has been applied to study proteins attached to poliovirion RNA and to the viral double-stranded intracellular RF form. A protein is found at the 5' end of the plus strand virion RNA, and protein components are found at both ends of the duplex RF. In the RF as usually extracted, there is frequently a larger or compound protein aggregate at the end which contains the 3' end of the plus strand and the 5' end of the minus strand. Banding in CsCl-guanidinium hydrochloride in the presence of sarkosyl causes dissociation of some components of this aggregate, leaving both ends labeled with the covalently bound VPg. These results confirm and extend previous biochemical studies of proteins bound to poliovirion RNA and to the RF form.
Insights
Researchers visualized proteins on poliovirus RNA using electron microscopy. Proteins are located at the ends of viral RNA, including covalently bound VPg, confirming previous biochemical findings.
Area of Science:
- Molecular Biology
- Virology
- Biochemistry
Background:
- Poliovirus RNA contains associated proteins crucial for its replication and structure.
- Previous biochemical studies suggested the presence of proteins at the ends of poliovirus RNA and its replicative form (RF).
Purpose of the Study:
- To visualize and characterize proteins attached to poliovirus RNA and its double-stranded replicative form (RF) using a novel electron microscopy technique.
- To identify the location and nature of protein components associated with viral RNA ends.
Main Methods:
- Application of a recently developed electron microscopy method for visualizing proteins bound to nucleic acids.
- Analysis of proteins attached to poliovirion RNA and the intracellular double-stranded RF form of poliovirus.
- Differential extraction using CsCl-guanidinium hydrochloride and sarkosyl to dissociate protein aggregates.
Main Results:
- A protein was identified at the 5' end of the poliovirus plus-strand virion RNA.
- Protein components were observed at both ends of the double-stranded RF form.
- A large protein aggregate was frequently found at the RF end containing the 3' end of the plus strand and the 5' end of the minus strand.
- Dissociation of the aggregate revealed covalently bound VPg at both ends of the RF.
Conclusions:
- The study confirms and extends previous biochemical findings on proteins associated with poliovirus RNA and its RF.
- Electron microscopy provides direct visualization of protein-nucleic acid interactions at specific sites on viral RNA.
- VPg is a protein covalently attached to both ends of the poliovirus RF.