title: Changes in subcellular localization reveal interactions between human cytomegalovirus terminase subunits.
abstract: BACKGROUND
  During herpesvirus replication, terminase packages viral DNA into capsids. The subunits of herpes simplex virus terminase, UL15, UL28, and UL33, assemble in the cytoplasm prior to nuclear import of the complex.
  
  
  METHODS
  To detect similar interactions between human cytomegalovirus terminase subunits, the orthologous proteins UL89, UL56, and UL51 were expressed in HEK-293 T cells (via transfection) or insect cells (via baculovirus infection) and subcellular localizations were detected by cellular fractionation and confocal microscopy.
  
  
  RESULTS
  In both cell types, UL56 and UL89 expressed alone were exclusively cytoplasmic, whereas UL51 was ~50% nuclear. Both UL89 and UL56 became ~50% nuclear when expressed together, as did UL56 when expressed with UL51. Nuclear localization of each protein was greatest when all three proteins were co-expressed.
  
  
  CONCLUSIONS
  These results support inclusion of UL51 as an HCMV terminase subunit and suggest that nuclear import of human cytomegalovirus terminase may involve nuclear import signals that form cooperatively upon subunit associations.
authors.affiliation: Department of Pediatrics, Virginia Commonwealth University, Richmond, VA 23298-0163, USA.
authors.forename: Jian Ben
authors.initials: JB
authors.lastname: Wang
authors.forename: Yali
authors.initials: Y
authors.lastname: Zhu
authors.forename: Michael A
authors.initials: MA
authors.lastname: McVoy
authors.forename: Deborah S
authors.initials: DS
authors.lastname: Parris
mesh_terms: D021581:Active Transport, Cell Nucleus; D016367:Baculoviridae / Q000235:genetics / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism / Q000821:virology; D003587:Cytomegalovirus / Q000201:enzymology* / Q000235:genetics / Q000472:pathogenicity; D003586:Cytomegalovirus Infections / Q000378:metabolism / Q000821:virology; D003593:Cytoplasm / Q000378:metabolism / Q000821:virology; D042003:DNA Packaging; D004261:DNA Replication; D004279:DNA, Viral / Q000235:genetics / Q000378:metabolism*; D005822:Genetic Vectors / Q000235:genetics / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D018613:Microscopy, Confocal; D025941:Protein Interaction Mapping; D061987:Sf9 Cells; D014162:Transfection; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*; D015678:Viral Structural Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D004279:DNA, Viral; C090238:UL56 protein, cytomegalovirus; C436448:UL89 protein, Cytomegalovirus; D014764:Viral Proteins; D015678:Viral Structural Proteins