THE HUMAN CYTOMEGALOVIRUS UL97 PROTEIN IS PHOSPHORYLATED AND A COMPONENT OF VIRIONS

The expression of the human cytomegalovirus (HCMV) UL97 open reading f rame in infected or transfected cells in the presence of the antiherpe s compound ganciclovir (GCV) results in the intracellular phosphorylat ion of GCV. There are conventional kinase domains within the UL97-enco ded protein (pUL97). However, the role of pUL97 in the HCMV replicatio n cycle, and the mechanism by which it causes phosphorylation of GCV, are currently unknown. Herein, the biosynthesis and biogenesis of pUL9 7 was studied in HCMV-infected cells, pUL97 is expressed with early-la te kinetics and is posttranslationally modified by phosphorylation. Th is phosphorylation occurs within 1 hr after synthesis, affects the ele ctrophoretic mobility of pUL97, and is independent of the presence of other HCMV proteins. pUL97 was localized to the nucleus of infected ce lls and found in the HCMV virions. Thus, pUL97 is a virion phosphoprot ein, and a likely tegument component. (C) 1997 Academic Press.