THE LARGE SUBUNIT OF HERPES-SIMPLEX VIRUS TYPE-2 RIBONUCLEOTIDE REDUCTASE (ICP10) IS ASSOCIATED WITH THE VIRION TEGUMENT AND HAS PK ACTIVITY

The large subunit of herpes simplex virus type 2 (HSV-2) ribonucleotid e reductase (ICP10) was identified in sucrose gradient-purified HSV-2 virions by immunoprecipitation/immunoblotting with antibody specific f or the protein kinase (PK) domain. Immunoblotting of individual gradie nt fractions indicated that ICP10 cosediments with the major capsid pr otein and the highest virus titers. ICP10 was not labeled by iodinatio n of purified virions, indicating that it is not located on the virion surface. After envelope glycoproteins were removed by detergent treat ment, ICP10 was associated with capsid-tegument particles and became s ensitive to trypsin digestion. The capsid-tegument-associated ICP10 wa s phosphorylated and had PK activity in vitro and on Immobilon membran es. A mutant ICP10 protein deleted in the PK domain (p95) was also ass ociated with purified virions (ICP10 Delta PK virus) but it lacked PK activity. The data indicate that ICP10 is contained within the tegumen t component where it retains intrinsic PK activity. (C) 1997 Academic Press.