Induced formation of covalent bonds between nucleoprotein components. V. UV or bisulfite induced polynucleotide-protein crosslinkage in bacteriophage MS2

UV (lambda = 254 nm) irradiation of bacteriophage MS2 or its treatment with bisulfite induce covalent crosslinkage of the RNA to the coat protein. epilsonN-(2-oxopyrimidyl-4)-lysine was found in the phage hydrolysates after either type of treatment. An equimolar mixture of 0-methylhydroxylamine and bisulfite causes complete disappearance of the cross-links. This led to the conclusion that one of the factors responsible for the UV-induced polynucleotide-protein crosslinkage and the main factor in treatment with bisulfite is substitution of the exocyclic amino group of the activated cytosine nucleus by the lysine residue epilson-amino group of the protein.