Polar Assembly of Clover Yellow Mosaic Virus

Abstract

SUMMARY Clover yellow mosaic virus (CYMV) protein encapsidates its RNA at pH 7.5, low ionic strength and at a temperature of 25 °C. Protected RNA fragments extracted from the initiation complexes contained the cap structure m7GpppGp in the stoichiometric proportions expected for fragment sizes. These results were consistent with the location of the initiation site for assembly at or near the 5′ end of RNA; consequently, the maturation process is polar (5′ to 3′ direction). This strengthens the case for polar initiation as an alternative to internal initiation in the assembly of helical plant viruses.