An electron microscope study of the proteins attached to polio virus RNA and its replicative form (RF).

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.