Protein kinases associated with the adenovirus single-stranded DNA-binding protein

Protein kinase activities copurifying with the 72000-Mr DNA-binding protein of adenovirus on DNA-cellulose chromatography and gel filtration in acrylamide/agarose have been partially characterized and purified. One of these kinases was found to phosphorylate efficiently the viral DNA-binding protein in vitro and to be stimulated severalfold by the addition of histones, protamine, or polyamines. The kinase does not, however, phosphorylate histones, protamine, casein, or phosvitin. A second protein kinase was also recovered from single-stranded DNA-cellulose which is able to phosphorylate the 72000-Mr DNA-binding protein, but which is inhibited by the addition of histones. Phosphorylation in vitro of the 72000-Mr DNA-binding protein from the ts125 mutants of adenovirus by the histone-stimulated protein kinase was found to be thermosensitive.