MURINE GAMMAHERPESVIRUS-68 ENCODES HOMOLOGS OF THYMIDINE KINASE AND GLYCOPROTEIN-H - SEQUENCE, EXPRESSION, AND CHARACTERIZATION OF PYRIMIDINE KINASE-ACTIVITY

We have sequenced a 4.5-kb fragment of DNA spanning the junction of th e BamHI D and E fragments of murine gammaherpesvirus-68 (MHV-68). This sequence was found to code for two major open reading frames (oris) o f 1934 and 2192 bp which showed significant homology to the thymidine kinase (TK) and glycoprotein H (gH) sequences of other gammaherpesviru ses. Upstream from the TK gene another orf was found which showed amin o acid sequence homology to the HSV1 UL24 gene. Analysis of the 1934-b p orf revealed The presence of all six of the recognized sites that ar e conserved between herpesvirus TKs although, uniquely among sequenced herpesvirus TK enzymes, MHV-68 lacks the consensus nucleotide binding site GXXGXGK, the second glycine being replaced by alanine. The MHV-6 8 TK has a predicted M(r) of 68,443, while the gH is predicted to have a M(r) of 82,890. Northern blot analysis showed an early TK message o f 2.6 kb and a late gH-specific message of 2.5 kb. Both TK and gH prob es detected a 4.3-kb late message, implying that this late message spa ns gH and TK. The TK coding sequence was expressed using an in vitro t ranscription translation system and was shown to encode functional TK activity. (C) 1996 Academic Press, Inc.