Interactions of Ribonucleotide Polymers with Tobacco Mosaic Virus Protein to form Virus-like Particles

Abstract

THE purified protein and ribonucleic acid constituents of tobacco mosaic virus can be combined in vitro to form infectious nucleoprotein rods which resemble the original virus in size and shape and which have their nucleic acid surrounded by protein as in the virus¹. Although the viral nucleic acid is necessary for infectivity, the formation of rods seems to depend on an inherent property of the viral protein; the latter can be aggregated in the absence of nucleic acid to form cylindrical tubes which superficially resemble the virus² but possess no infectivity. When the viral nucleic acid is present, it occupies a region within the tube and apparently serves to ‘cement’ the protein sub-units together, since the nucleoprotein particles are stable at pH values higher than those at which the protein tubes disintegrate². This cementing function might be thought to depend on some property specific to the nucleic acid of tobacco mosaic virus. In order to investigate such a possibility, we have studied the interactions of the viral protein with several widely differing artificial and natural ribonucleotide polymers.