[The effect of proteolytic cleavage of potato virus X coat protein on its ability to self-assemble with RNA and viral infectivity]. / Vliianie proteoliticheskogo rasshchepleniia belka obolochki X-virusa kartofelia na ego sposobnost' k rekonstruktsii s RNK i na infektsionnost' virusa.

The process of proteolytic cleavage of potato virus X coat protein molecules inside the virions and in the dissociated state in the course of their purification and storage has been studied. In agreement with the previous reports, the intact form (Ps) of the coat protein in the viral particles was found to be gradually cleaved to three discrete lower molecular forms (Pi, Pf, Pu). During the storage of the dissociated coat protein preparations further cleavage was observed with formation of at least three additional lower molecular weight forms (Ppa, Ppb, Ppc). The location of proteolytic cleavage sites leading to formation of Ppa form was determined. The shortened forms Pi, Pf, Pu and Ppa (and possibly Ppc) were found to be incorporated into the viral particles in the course of reconstitution in vitro with the viral RNA. Infectivity of the virus containing only intact (Ps) form of the protein was found to be two to three folds higher than that of the virus containing only Pf form of the coat protein.

[Difference in the mechanism of self-assembly in vitro in tobacco mosaic virus and potato virus X]. / Razlichiia v mekhanizmakh samosborki in vitro virusa tabachnoi mozaiki i X-virusa kartofelia.

The effects of 254 nm UV-irradiation of tobacco mosaic virus (TMV) and potato virus X (PVX) RNA preparations on the RNA ability to self-assembly in vitro with the viral coat proteins were studied. It was found that while TMV RNA ability to assemble with the homologous protein is rapidly inactivated by the UV-irradiation, PVX RNA ability to be encapsidated by the PVX coat protein is quite resistant to the irradiation. More than that, the irradiation of TMV RNA with the dose strongly inhibiting its assembly with the homologous protein, did not result in any significant inhibition of this RNA ability to be coated with the PVX protein. The results testify to the profound differences in the mechanisms of RNA-protein interactions in the processes of self-assembly in vitro of tobamoviruses and potexviruses.