Herpes simplex virus phosphoproteins. II. Characterization of the virion protein kinase and of the polypeptides phosphorylated in the virion

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Abstract
The protein kinase associated with purified herpes simplex virus 1 and 2 virions partitioned with the capsid-tegument structures and was not solubilized by nonionic detergents and low, non-inhibitory concentrations of urea. The enzyme required Mg2+ or Mn2+ and utilized ATP or GTP. The activity was enhanced by non-ionic detergents and by Na+ even in the presence of high concentrations of Mg2+, but not by cyclic nucleotides. The enzyme associated with capsid-tegument structures phosphorylated virion polypeptides only; exogenously added substrates (acidic and basic histones, casein, phosphovitin, protamine and bovine serum albumin) were not phosphorylated. The major phosphorylated species were virion polypeptides (VP) 1-2, 4, 11-12, 13-14, 18.7-18.8 and 23. VP 18.7 and VP 18.8 were not previously detected but may be phosphorylated forms of polypeptides co-migrating with VP 19. Of the remainder, only VP 23 was previously identified as a capsid protein; the others are constituents of the tegument or of the under surface of the virion envelope. The distribution of the phosphate bound to viral polypeptides varied depending on the Mg2+ concentration and pH. In the absence of dithiothreitol, in vitro phosphate exchange was demonstrable in VP 23 and to a lesser extent in 2 other polypeptides on sequential phosphorylation first with saturating amounts of unlabeled ATP and then with [.gamma.-32P]ATP. Analysis of the virion polypeptides specified by herpes simplex virus 1 .times. herpes simplex virus 2 recombinants indicates that the genes specifying the polypeptides which serve as a substrate for the protein kinase map in the unique sequences near the left and right reinterated DNA sequences of the L component.